id string | problem_number int64 | title string | statement string | plain_statement string | precise_statement string | category string | category_id int64 | category_name string | subdiscipline string | set_id int64 | question_types list | earth_system_components list | environmental_media list | processes list | spatial_scale string | region string | temporal_scale string | geologic_era string | observables list | inferred_properties list | governing_relations list | background string | what_would_settle_it string | status string | consensus_state string | research_classification string | published bool | difficulty string | difficulty_level int64 | origin_year int64 | proposed_by string | literature_checked_at timestamp[s] | related_problems list | reference_dois list | references list |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
UEARTH-000001 | 1 | Nonstationarity of the Hydrological Cycle Under Climate and Environmental Change (UPH 1) | Is the terrestrial hydrological cycle regionally accelerating or decelerating under coupled climate and environmental change, and are there abrupt tipping thresholds in catchment water balance partitioning? | Is the water cycle speeding up or slowing down across different regions as climate and land use change, and does it have tipping points? | Across major hydroclimatic regimes and multi-decadal instrumental records, how do radiative forcing, atmospheric evaporative demand, and land-cover change alter catchment-scale precipitation-runoff-evapotranspiration partitioning ($P - E - Q = \Delta S$), and under what boundary conditions does nonlinear storage-discha... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | catchment_runoff_transit_time_uph | 2 | [
"mechanism",
"budget"
] | [
"river",
"vadose_zone"
] | [
"freshwater_surface",
"pore_water"
] | [
"hydrological_partitioning_and_runoff",
"groundwater_flow_and_transport"
] | hillslope_to_catchment | Global and Representative Regional Observatories | synoptic_to_seasonal | Anthropocene | [
"high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge",
"nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions"
] | [
"emergent catchment-scale storage-discharge constitutive relations from heterogeneous hillslope preferential flow"
] | [
"Kirchner dynamical catchment storage-discharge sensitivity $g(Q) = dQ/dS = (-dQ/dt) / (Q - P + E)$ and power-law recession $-dQ/dt = a Q^b$",
"master transit-time StorAge Selection (SAS) transport $\\partial_t S_T(T, t) + \\partial_T S_T(T, t) = J(t) - Q(t) \\Omega_Q(S_T, t) - E(t) \\Omega_E(S_T, t)$"
] | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 1); corroborated across Jha et al. (2026) and Tanner et al. (2015). Remains open due to coupled convective vs. stratiform storm hyetographs, antecedent soil moisture, and seasonal potential evapotranspiration and bedroc... | Co-located observations of high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge and nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions across Global and Representative Regional Observatories coupl... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-013460",
"UEARTH-000015",
"UEARTH-019411"
] | [
"10.1080/02626667.2019.1620507",
"10.1016/j.htopen.2026.100092",
"10.1080/02626667.2015.1052453",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Time Variability and Change (UPH 1), DOI:10.1080/02626667.2019.1620507",
"Jha et al. (2026), H2Open Journal, DOI:10.1016/j.htopen.2026.100092",
"Tanner et al. (2015), Hydrological Sciences Journal, DOI:10.1080/02626667.2015.105... |
UEARTH-000002 | 2 | Cold-Region Runoff and Groundwater Response to Cryospheric Thaw (UPH 2) | How will cold-region catchment runoff generation, seasonality, and subsurface groundwater flow paths reorganize as glaciers retreat, snowpacks diminish, and continuous permafrost degrades? | How will meltwater and groundwater flow change in cold regions as snow, glaciers, and permafrost thaw? | In alpine and high-latitude catchments undergoing snow-to-rain transitions, glacier recession, and active-layer deepening, how does the loss of cryospheric storage and frozen aquitards alter hydraulic connectivity, baseflow recession constants, and peak discharge timing (governed by Kirchner dynamical catchment storage... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | catchment_runoff_transit_time_uph | 2 | [
"mechanism"
] | [
"river",
"vadose_zone"
] | [
"freshwater_surface",
"pore_water"
] | [
"hydrological_partitioning_and_runoff",
"groundwater_flow_and_transport"
] | hillslope_to_catchment | Pan-Arctic Cryosphere, Greenland, and Boreal Permafrost Domain | synoptic_to_seasonal | Holocene | [
"high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge",
"nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions"
] | [
"paradoxical rapid mobilization of 'old' pre-event stored water during storm hydrograph peaks"
] | [
"Kirchner dynamical catchment storage-discharge sensitivity $g(Q) = dQ/dS = (-dQ/dt) / (Q - P + E)$ and power-law recession $-dQ/dt = a Q^b$",
"master transit-time StorAge Selection (SAS) transport $\\partial_t S_T(T, t) + \\partial_T S_T(T, t) = J(t) - Q(t) \\Omega_Q(S_T, t) - E(t) \\Omega_E(S_T, t)$"
] | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 2); corroborated across Shi et al. (2026) and Cheng et al. (2018). Remains open due to coupled convective vs. stratiform storm hyetographs, antecedent soil moisture, and seasonal potential evapotranspiration and bedrock... | Co-located observations of high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge and nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions across Pan-Arctic Cryosphere, Greenland, and Boreal Permafros... | open | mechanism_known_magnitude_uncertain | OPEN-VERIFIED | true | medium | 3 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-013442",
"UEARTH-000005",
"UEARTH-005323"
] | [
"10.1080/02626667.2019.1620507",
"10.1128/aem.00485-26",
"10.1029/2017wr021875",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Time Variability and Change (UPH 2), DOI:10.1080/02626667.2019.1620507",
"Shi et al. (2026), Applied and environmental microbiology, DOI:10.1128/aem.00485-26",
"Cheng et al. (2018), Water Resources Research, DOI:10.1029/2017wr0... |
UEARTH-000003 | 3 | Climatic and Catchment Signals in Decadal Flood Regime Changes (UPH 3) | What are the relative causal contributions of synoptic atmospheric circulation shifts, antecedent soil-moisture memory, and land-surface modifications to observed multi-decadal changes in river flood magnitude, frequency, and seasonality? | What controls multi-decadal changes in river flood size, timing, and frequency across different catchments? | Across continental river networks, how do shifts in extreme convective versus stratiform precipitation interact with snowmelt timing, catchment wetness state, and channel-floodplain storage to govern nonstationary flood frequency distributions (governed by master transit-time StorAge Selection (SAS) transport $\partial... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | catchment_runoff_transit_time_uph | 2 | [
"mechanism",
"predictability"
] | [
"river",
"vadose_zone"
] | [
"freshwater_surface",
"pore_water"
] | [
"hydrological_partitioning_and_runoff",
"groundwater_flow_and_transport"
] | hillslope_to_catchment | Global and Representative Regional Observatories | synoptic_to_seasonal | Anthropocene | [
"high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge",
"nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions"
] | [
"emergent catchment-scale storage-discharge constitutive relations from heterogeneous hillslope preferential flow"
] | [
"Kirchner dynamical catchment storage-discharge sensitivity $g(Q) = dQ/dS = (-dQ/dt) / (Q - P + E)$ and power-law recession $-dQ/dt = a Q^b$",
"master transit-time StorAge Selection (SAS) transport $\\partial_t S_T(T, t) + \\partial_T S_T(T, t) = J(t) - Q(t) \\Omega_Q(S_T, t) - E(t) \\Omega_E(S_T, t)$"
] | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 3); corroborated across Jiang et al. (2023) and Alkama et al. (2010). Remains partially solved due to coupled convective vs. stratiform storm hyetographs, antecedent soil moisture, and seasonal potential evapotranspirat... | Co-located observations of high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge and nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions across Global and Representative Regional Observatories coupl... | partially_solved | regional_resolution_only | PARTIAL-PROGRESS | true | medium | 3 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-013461",
"UEARTH-013471",
"UEARTH-005069"
] | [
"10.1080/02626667.2019.1620507",
"10.1016/j.isci.2023.106837",
"10.1029/2009jd013408",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Time Variability and Change (UPH 3), DOI:10.1080/02626667.2019.1620507",
"Jiang et al. (2023), iScience, DOI:10.1016/j.isci.2023.106837",
"Alkama et al. (2010), Journal of Geophysical Research Atmospheres, DOI:10.1029/2009jd013... |
UEARTH-000004 | 4 | Land-Cover Change and Soil Feedbacks on Drought Onset and Termination (UPH 4) | How do vegetation structure, rooting depth, and soil hydraulic degradation amplify or dampen the propagation of meteorological drought into agricultural and hydrological drought, and what controls drought termination? | How do changes in land cover and soil properties influence how droughts start, persist, and end? | In water-limited and energy-limited catchments, what nonlinear couplings among canopy stomatal conductance, root-zone water depletion, soil desiccation cracking, and boundary-layer moisture recycling govern the persistence and recovery threshold of multi-year hydrological droughts (governed by Generalized Extreme Value... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | hydroclimatic_extremes_floods_drought_propagation | 2 | [
"mechanism"
] | [
"hydrosphere_freshwater",
"river"
] | [
"freshwater_surface",
"groundwater"
] | [
"hydrological_partitioning_and_runoff",
"groundwater_flow_and_transport"
] | river_basin_or_aquifer | Global and Representative Regional Observatories | interannual_to_decadal | Holocene | [
"multi-decade stream-gauge networks, standardized precipitation/runoff/groundwater drought indices, and satellite altimetry",
"coupled land-surface/hydrodynamic routing models and remotely sensed irrigation/reservoir storage records"
] | [
"attenuation, lag time, and nonlinear memory governing meteorological-to-soil-to-groundwater drought propagation"
] | [
"Generalized Extreme Value (GEV) non-stationary return level $G(x; \\mu(t), \\sigma(t), \\xi) = \\exp\\{-[1 + \\xi ((x - \\mu(t))/\\sigma(t))]^{-1/\\xi}\\}$",
"runoff-precipitation elasticity $\\varepsilon_Q = (\\bar{P}/\\bar{Q}) (dQ/dP)$ shifting across multi-year drought states"
] | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 4); corroborated across Liu et al. (2024) and Liu et al. (2023). Remains open due to coupled persistent precipitation deficits, extreme atmospheric-river or monsoon rainfall, and human abstraction/impoundment and basin ... | Co-located observations of multi-decade stream-gauge networks, standardized precipitation/runoff/groundwater drought indices, and satellite altimetry and coupled land-surface/hydrodynamic routing models and remotely sensed irrigation/reservoir storage records across Global and Representative Regional Observatories coup... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | medium | 3 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-014467",
"UEARTH-014118",
"UEARTH-005199"
] | [
"10.1080/02626667.2019.1620507",
"10.1002/eco.2630",
"10.1016/j.scitotenv.2023.162771",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Time Variability and Change (UPH 4), DOI:10.1080/02626667.2019.1620507",
"Liu et al. (2024), Ecohydrology, DOI:10.1002/eco.2630",
"Liu et al. (2023), The Science of the total environment, DOI:10.1016/j.scitotenv.2023.162771",
... |
UEARTH-000005 | 5 | Spatial Heterogeneity and Connectivity in Catchment Runoff and Evapotranspiration (UPH 5) | What causes the spatial variability and organization of runoff, evaporation, and subsurface water-flow connectivity across hillslopes and catchments, and how do those patterns violate homogeneous continuum assumptions? | What controls how runoff, evaporation, and underground water pathways vary in space across a watershed? | Across hillslope-to-catchment scales, how do bedrock topography, macropore networks, soil catenas, and aspect-driven radiation gradients organize preferential subsurface flow and evapotranspiration fluxes (governed by master transit-time StorAge Selection (SAS) transport $\partial_t S_T(T, t) + \partial_T S_T(T, t) = J... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | catchment_runoff_transit_time_uph | 2 | [
"mechanism",
"scaling"
] | [
"river",
"vadose_zone"
] | [
"freshwater_surface",
"pore_water"
] | [
"hydrological_partitioning_and_runoff",
"groundwater_flow_and_transport"
] | hillslope_to_catchment | Global and Representative Regional Observatories | synoptic_to_seasonal | Anthropocene | [
"high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge",
"nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions"
] | [
"emergent catchment-scale storage-discharge constitutive relations from heterogeneous hillslope preferential flow"
] | [
"Kirchner dynamical catchment storage-discharge sensitivity $g(Q) = dQ/dS = (-dQ/dt) / (Q - P + E)$ and power-law recession $-dQ/dt = a Q^b$",
"master transit-time StorAge Selection (SAS) transport $\\partial_t S_T(T, t) + \\partial_T S_T(T, t) = J(t) - Q(t) \\Omega_Q(S_T, t) - E(t) \\Omega_E(S_T, t)$"
] | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 5); corroborated across Zeng et al. (2022) and Wang et al. (2024). Remains open due to coupled convective vs. stratiform storm hyetographs, antecedent soil moisture, and seasonal potential evapotranspiration and bedrock... | Co-located observations of high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge and nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions across Global and Representative Regional Observatories coupl... | open | scale_dependent_disagreement | OPEN-VERIFIED | true | medium | 3 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-013658",
"UEARTH-013492",
"UEARTH-019012"
] | [
"10.1080/02626667.2019.1620507",
"10.3390/rs14153628",
"10.1016/j.scitotenv.2024.173549",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Space Variability and Scaling (UPH 5), DOI:10.1080/02626667.2019.1620507",
"Zeng et al. (2022), Remote Sensing, DOI:10.3390/rs14153628",
"Wang et al. (2024), The Science of the total environment, DOI:10.1016/j.scitotenv.2024.17... |
UEARTH-000006 | 6 | Upscaling State-Dependent Hydrological Laws Across Spatial Scales (UPH 6) | What are the effective hydrological laws at the catchment scale, and how do they emerge and change with spatial scale from pore-scale Darcy-Richards physics to hillslope and river-basin scales? | What are the physical laws of water flow at the watershed scale, and how do they change with scale? | Can closed-form constitutive relations link catchment-wide storage ($S$) to discharge ($Q$) and evapotranspiration ($E$) across spatial scales ($10^{-3}\,\mathrm{m}$ to $10^{5}\,\mathrm{m}$), or do threshold connectivity and hysteresis prevent scale-invariant parameterizations? | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | catchment_runoff_transit_time_uph | 2 | [
"mechanism",
"scaling"
] | [
"river",
"vadose_zone"
] | [
"freshwater_surface",
"pore_water"
] | [
"hydrological_partitioning_and_runoff",
"groundwater_flow_and_transport"
] | hillslope_to_catchment | Global and Representative Regional Observatories | synoptic_to_seasonal | Holocene | [
"high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge",
"nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions"
] | [
"paradoxical rapid mobilization of 'old' pre-event stored water during storm hydrograph peaks"
] | [
"Kirchner dynamical catchment storage-discharge sensitivity $g(Q) = dQ/dS = (-dQ/dt) / (Q - P + E)$ and power-law recession $-dQ/dt = a Q^b$",
"master transit-time StorAge Selection (SAS) transport $\\partial_t S_T(T, t) + \\partial_T S_T(T, t) = J(t) - Q(t) \\Omega_Q(S_T, t) - E(t) \\Omega_E(S_T, t)$"
] | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 6); corroborated across Jha et al. (2026) and Guo et al. (2026). Remains open due to coupled convective vs. stratiform storm hyetographs, antecedent soil moisture, and seasonal potential evapotranspiration and bedrock t... | Co-located observations of high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge and nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions across Global and Representative Regional Observatories coupl... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-013452",
"UEARTH-013477",
"UEARTH-015123"
] | [
"10.1080/02626667.2019.1620507",
"10.1016/j.htopen.2026.100092",
"10.3390/land15081393",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Space Variability and Scaling (UPH 6), DOI:10.1080/02626667.2019.1620507",
"Jha et al. (2026), H2Open Journal, DOI:10.1016/j.htopen.2026.100092",
"Guo et al. (2026), Land, DOI:10.3390/land15081393",
"B. Arheimer, C. Cudennec,... |
UEARTH-000007 | 7 | Bedrock-Controlled Subsurface Flow in the Critical Zone (UPH 7) | Why is most of the water in rivers during floods 'old' pre-event water, and how do deep weathered bedrock and saprolite fractures control transit-time distributions and runoff generation? | Why does floodwater in rivers consist mostly of old underground water rather than fresh rainwater, and what role does deep bedrock play? | In upland catchments, what pressure-wave celerity versus advective velocity mechanisms in the vadose zone, saprolite, and fractured bedrock mobilize pre-event stored water into stream channels during storm events while maintaining long mean transit times (governed by master transit-time StorAge Selection (SAS) transpor... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | catchment_runoff_transit_time_uph | 2 | [
"mechanism"
] | [
"river",
"vadose_zone"
] | [
"freshwater_surface",
"pore_water"
] | [
"hydrological_partitioning_and_runoff",
"groundwater_flow_and_transport"
] | hillslope_to_catchment | Global and Representative Regional Observatories | synoptic_to_seasonal | Anthropocene | [
"high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge",
"nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions"
] | [
"emergent catchment-scale storage-discharge constitutive relations from heterogeneous hillslope preferential flow"
] | [
"Kirchner dynamical catchment storage-discharge sensitivity $g(Q) = dQ/dS = (-dQ/dt) / (Q - P + E)$ and power-law recession $-dQ/dt = a Q^b$",
"master transit-time StorAge Selection (SAS) transport $\\partial_t S_T(T, t) + \\partial_T S_T(T, t) = J(t) - Q(t) \\Omega_Q(S_T, t) - E(t) \\Omega_E(S_T, t)$"
] | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 7); corroborated across Safeeq et al. (2021) and Shanley et al. (2014). Remains partially solved due to coupled convective vs. stratiform storm hyetographs, antecedent soil moisture, and seasonal potential evapotranspir... | Co-located observations of high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge and nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions across Global and Representative Regional Observatories coupl... | partially_solved | dominant_hypothesis_unconfirmed | PARTIAL-PROGRESS | true | medium | 3 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-000002",
"UEARTH-000005",
"UEARTH-005624"
] | [
"10.1080/02626667.2019.1620507",
"10.1002/hyp.14199",
"10.1002/hyp.10377",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Space Variability and Scaling (UPH 7), DOI:10.1080/02626667.2019.1620507",
"Safeeq et al. (2021), Hydrological Processes, DOI:10.1002/hyp.14199",
"Shanley et al. (2014), Hydrological Processes, DOI:10.1002/hyp.10377",
"B. Arh... |
UEARTH-000008 | 8 | Soft-Data Constraints on Spatially Distributed Hydrological Models (UPH 8) | How can qualitative hydrological process knowledge, landscape organization, and indirect remote-sensing proxies constrain equifinality and structural uncertainty in spatially distributed hydrological models? | How can field observations of landscape patterns reduce uncertainty when modeling water flow across catchments? | In under-gauged and heterogeneous basins, what information-theoretic combination of hydrochemical tracers, cosmic-ray neutron soil moisture, thermal infrared patterns, and geomorphic organization uniquely identifies subsurface storage-discharge parameters (governed by Kirchner dynamical catchment storage-discharge sens... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | catchment_runoff_transit_time_uph | 2 | [
"mechanism",
"observability"
] | [
"river",
"vadose_zone"
] | [
"freshwater_surface",
"pore_water"
] | [
"hydrological_partitioning_and_runoff",
"groundwater_flow_and_transport"
] | hillslope_to_catchment | Global and Representative Regional Observatories | synoptic_to_seasonal | Holocene | [
"high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge",
"nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions"
] | [
"paradoxical rapid mobilization of 'old' pre-event stored water during storm hydrograph peaks"
] | [
"Kirchner dynamical catchment storage-discharge sensitivity $g(Q) = dQ/dS = (-dQ/dt) / (Q - P + E)$ and power-law recession $-dQ/dt = a Q^b$",
"master transit-time StorAge Selection (SAS) transport $\\partial_t S_T(T, t) + \\partial_T S_T(T, t) = J(t) - Q(t) \\Omega_Q(S_T, t) - E(t) \\Omega_E(S_T, t)$"
] | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 8); corroborated across Pan et al. (2023) and Zheng et al. (2025). Remains open due to coupled convective vs. stratiform storm hyetographs, antecedent soil moisture, and seasonal potential evapotranspiration and bedrock... | Co-located observations of high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge and nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions across Global and Representative Regional Observatories coupl... | open | framework_dependent | OPEN-VERIFIED | true | medium | 3 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-013688",
"UEARTH-000047",
"UEARTH-005156"
] | [
"10.1080/02626667.2019.1620507",
"10.1016/j.scitotenv.2023.161852",
"10.1016/j.jenvman.2024.123939",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Space Variability and Scaling (UPH 8), DOI:10.1080/02626667.2019.1620507",
"Pan et al. (2023), The Science of the total environment, DOI:10.1016/j.scitotenv.2023.161852",
"Zheng et al. (2025), Journal of environmental managemen... |
UEARTH-000009 | 9 | Memory Effects and Extreme Flood Generation in Catchments (UPH 9) | How do catchment memory effects across event, seasonal, and multi-year timescales control the transition from ordinary rainfall-runoff response to catastrophic extreme floods? | How does a watershed's past moisture history trigger extreme, sudden flooding during heavy storms? | What physical threshold in vadose-zone saturation, perched water-table coalescence, and surface-subsurface runoff connectivity causes the storm runoff coefficient to step-change nonlinearly during extreme precipitation events (governed by master transit-time StorAge Selection (SAS) transport $\partial_t S_T(T, t) + \pa... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | catchment_runoff_transit_time_uph | 2 | [
"mechanism",
"predictability"
] | [
"river",
"vadose_zone"
] | [
"freshwater_surface",
"pore_water"
] | [
"hydrological_partitioning_and_runoff",
"groundwater_flow_and_transport"
] | hillslope_to_catchment | Global and Representative Regional Observatories | synoptic_to_seasonal | Anthropocene | [
"high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge",
"nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions"
] | [
"emergent catchment-scale storage-discharge constitutive relations from heterogeneous hillslope preferential flow"
] | [
"Kirchner dynamical catchment storage-discharge sensitivity $g(Q) = dQ/dS = (-dQ/dt) / (Q - P + E)$ and power-law recession $-dQ/dt = a Q^b$",
"master transit-time StorAge Selection (SAS) transport $\\partial_t S_T(T, t) + \\partial_T S_T(T, t) = J(t) - Q(t) \\Omega_Q(S_T, t) - E(t) \\Omega_E(S_T, t)$"
] | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 9); corroborated across Zeimetz (2017) and Ghanim (2020). Remains open due to coupled convective vs. stratiform storm hyetographs, antecedent soil moisture, and seasonal potential evapotranspiration and bedrock topograp... | Co-located observations of high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge and nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions across Global and Representative Regional Observatories coupl... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | medium | 3 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-013492",
"UEARTH-000048",
"UEARTH-005547"
] | [
"10.1080/02626667.2019.1620507",
"10.5075/epfl-lchcomm-68",
"10.17485/ijst/2020/v13i03/121966",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Variability of Extremes (UPH 9), DOI:10.1080/02626667.2019.1620507",
"Zeimetz (2017), Infoscience (Ecole Polytechnique Fédérale de Lausanne), DOI:10.5075/epfl-lchcomm-68",
"Ghanim (2020), Indian Journal of Science and Technolog... |
UEARTH-000010 | 10 | Runoff-Percolation Partitioning Under Megadroughts and Deluges (UPH 10) | Why does runoff-precipitation elasticity shift nonlinearly during persistent multi-year droughts, and how does groundwater-surface water decoupling delay hydrological recovery after drought termination? | Why do some rivers produce much less water than expected during multi-year droughts even when rain returns? | During prolonged hydroclimatic anomalies, how do water-table decline below streambed elevation, root-system plasticity, and vadose-zone hydraulic conductivity reduction induce multi-year hysteresis in annual catchment runoff ratios (governed by Kirchner dynamical catchment storage-discharge sensitivity $g(Q) = dQ/dS = ... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | catchment_runoff_transit_time_uph | 2 | [
"mechanism",
"budget"
] | [
"river",
"vadose_zone"
] | [
"freshwater_surface",
"pore_water"
] | [
"hydrological_partitioning_and_runoff",
"groundwater_flow_and_transport"
] | hillslope_to_catchment | Global and Representative Regional Observatories | synoptic_to_seasonal | Holocene | [
"high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge",
"nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions"
] | [
"paradoxical rapid mobilization of 'old' pre-event stored water during storm hydrograph peaks"
] | [
"Kirchner dynamical catchment storage-discharge sensitivity $g(Q) = dQ/dS = (-dQ/dt) / (Q - P + E)$ and power-law recession $-dQ/dt = a Q^b$",
"master transit-time StorAge Selection (SAS) transport $\\partial_t S_T(T, t) + \\partial_T S_T(T, t) = J(t) - Q(t) \\Omega_Q(S_T, t) - E(t) \\Omega_E(S_T, t)$"
] | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 10); corroborated across Tanner et al. (2015) and Peng et al. (2026). Remains open due to coupled convective vs. stratiform storm hyetographs, antecedent soil moisture, and seasonal potential evapotranspiration and bedr... | Co-located observations of high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge and nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions across Global and Representative Regional Observatories coupl... | open | active_debate | OPEN-VERIFIED | true | medium | 3 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-000170",
"UEARTH-013412",
"UEARTH-019294"
] | [
"10.1080/02626667.2019.1620507",
"10.1080/02626667.2015.1052453",
"10.3390/biology15100811",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Variability of Extremes (UPH 10), DOI:10.1080/02626667.2019.1620507",
"Tanner et al. (2015), Hydrological Sciences Journal, DOI:10.1080/02626667.2015.1052453",
"Peng et al. (2026), Biology, DOI:10.3390/biology15100811",
"B. A... |
UEARTH-000011 | 11 | Richards and Saint-Venant Equations Breakdown in Preferential Flow Systems (UPH 11) | Under what field conditions can novel non-Darcian and non-Fickian formulations replace the classical Richards and Saint-Venant equations to represent macropore, film, and preferential subsurface flow? | How can hydrologists replace standard soil-water equations that fail when water flows rapidly through cracks and root channels? | In structured soils and fractured rock where disequilibrium preferential flow dominates over capillary matrix diffusion, what dual-permeability, Stokes-viscous film, or fractional-derivative transport formulation predicts both pressure propagation and solute breakthrough (governed by Budyko hydroclimatic partitioning $... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | vadose_zone_evapotranspiration_ecohydrology | 2 | [
"mechanism"
] | [
"vadose_zone",
"critical_zone"
] | [
"pore_water",
"soil"
] | [
"hydrological_partitioning_and_runoff",
"ecosystem_disturbance_and_biophysical_feedback"
] | hillslope_to_catchment | Global and Representative Regional Observatories | diurnal_to_synoptic | Anthropocene | [
"cosmic-ray neutron rover soil moisture, eddy-covariance latent heat fluxes, and xylem/soil water stable isotopes",
"sap-flow sensors, electrical resistivity imaging of root zones, and SMAP/Sentinel-1 microwave soil moisture"
] | [
"ecohydrological separation ('two water worlds') between tightly bound matrix water used by roots and mobile recharge water"
] | [
"Richards unsaturated flow $\\partial_t \\theta(\\psi) = \\nabla \\cdot [K(\\psi) \\nabla (\\psi + z)] - S_{\\mathrm{root}}(\\psi)$ coupled with Penman-Monteith evapotranspiration $\\lambda E = [\\Delta (R_n - G) + \\rho_a c_p \\mathrm{VPD} / r_a] / [\\Delta + \\gamma (1 + r_s / r_a)]$",
"Budyko hydroclimatic par... | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 11); corroborated across Guo et al. (2026) and Cavelan et al. (2025). Remains open due to coupled vapor pressure deficit (VPD), solar radiation, and intermittent rainfall infiltration pulses and soil water retention cur... | Co-located observations of cosmic-ray neutron rover soil moisture, eddy-covariance latent heat fluxes, and xylem/soil water stable isotopes and sap-flow sensors, electrical resistivity imaging of root zones, and SMAP/Sentinel-1 microwave soil moisture across Global and Representative Regional Observatories coupled with... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-013971",
"UEARTH-013983",
"UEARTH-005317"
] | [
"10.1080/02626667.2019.1620507",
"10.1021/acsomega.6c02253",
"10.1016/j.scitotenv.2025.181070",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Interfaces in Hydrology (UPH 11), DOI:10.1080/02626667.2019.1620507",
"Guo et al. (2026), ACS omega, DOI:10.1021/acsomega.6c02253",
"Cavelan et al. (2025), The Science of the total environment, DOI:10.1016/j.scitotenv.2025.1810... |
UEARTH-000012 | 12 | Transient Surface-Groundwater Exchange Across Hyporheic Zones (UPH 12) | What processes control the transient exchange of water, heat, and reactive solutes between river channels and alluvial aquifers across heterogeneous hyporheic zones from riffle to basin scales? | What controls how river water and groundwater mix and react beneath streambeds across different scales? | How do dynamic bedform migration, flood-wave hydrograph unsteadiness, sediment colmation, and bio-clogging modulate hyporheic residence-time distributions and redox zonation from sub-meter bedforms to alluvial valley corridors (governed by hyporheic Damköhler number $\mathrm{Da} = \tau_{\mathrm{res}} k_{\mathrm{rxn}}$ ... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | hyporheic_river_groundwater_lake_wetland | 2 | [
"mechanism",
"feedback"
] | [
"river",
"wetland"
] | [
"freshwater_surface",
"pore_water"
] | [
"groundwater_flow_and_transport",
"hydrological_partitioning_and_runoff"
] | reach | Global and Representative Regional Observatories | synoptic_to_seasonal | Holocene | [
"fiber-optic distributed temperature sensing (FO-DTS), 222Rn/He exchange tracers, and streambed vertical head gradients",
"SWOT wide-swath satellite water-surface elevation/slope and wetland inundation hydroperiod maps"
] | [
"multi-scale hyporheic exchange residence-time distributions driven by bedforms, bars, and meandering"
] | [
"hyporheic Damköhler number $\\mathrm{Da} = \\tau_{\\mathrm{res}} k_{\\mathrm{rxn}}$ governing aerobic-to-denitrifying redox transition along bedform streamlines",
"1D Saint-Venant transient channel-storage routing $\\partial_t A + \\partial_x Q = q_{\\mathrm{lat}} - q_{\\mathrm{hyp}}(A_s / A) \\partial_t (C_s - ... | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 12); corroborated across Terefe et al. (2026) and Sterte et al. (2018). Remains open due to coupled stage fluctuations, bedform-induced hydrostatic/hydrodynamic pressure gradients, and seasonal water-table shifts and st... | Co-located observations of fiber-optic distributed temperature sensing (FO-DTS), 222Rn/He exchange tracers, and streambed vertical head gradients and SWOT wide-swath satellite water-surface elevation/slope and wetland inundation hydroperiod maps across Global and Representative Regional Observatories coupled with proce... | open | scale_dependent_disagreement | OPEN-VERIFIED | true | medium | 3 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-013801",
"UEARTH-013652",
"UEARTH-015123"
] | [
"10.1080/02626667.2019.1620507",
"10.3390/w18111328",
"10.1016/j.jhydrol.2018.03.011",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Interfaces in Hydrology (UPH 12), DOI:10.1080/02626667.2019.1620507",
"Terefe et al. (2026), Water, DOI:10.3390/w18111328",
"Sterte et al. (2018), Journal of Hydrology, DOI:10.1016/j.jhydrol.2018.03.011",
"B. Arheimer, C. Cud... |
UEARTH-000013 | 13 | Subsurface Processes Governing Baseflow Recession and Streamflow Permanence (UPH 13) | What subsurface aquifer geometries, hydraulic diffusivity contrasts, and riparian evapotranspiration losses control the nonlinear shape of streamflow recession curves and the spatial contraction of perennial stream networks? | What underground processes control how fast rivers dry up between rainstorms and which stream reaches stop flowing? | Across headwater networks, how do power-law recession parameters ($-dQ/dt = aQ^b$) reflect the interplay among unconfined fractured-bedrock drainage, riparian phreatophyte uptake, and longitudinal stream-network disconnection? | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | catchment_runoff_transit_time_uph | 2 | [
"mechanism"
] | [
"river",
"vadose_zone"
] | [
"freshwater_surface",
"pore_water"
] | [
"hydrological_partitioning_and_runoff",
"groundwater_flow_and_transport"
] | hillslope_to_catchment | Global and Representative Regional Observatories | synoptic_to_seasonal | Anthropocene | [
"high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge",
"nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions"
] | [
"emergent catchment-scale storage-discharge constitutive relations from heterogeneous hillslope preferential flow"
] | [
"Kirchner dynamical catchment storage-discharge sensitivity $g(Q) = dQ/dS = (-dQ/dt) / (Q - P + E)$ and power-law recession $-dQ/dt = a Q^b$",
"master transit-time StorAge Selection (SAS) transport $\\partial_t S_T(T, t) + \\partial_T S_T(T, t) = J(t) - Q(t) \\Omega_Q(S_T, t) - E(t) \\Omega_E(S_T, t)$"
] | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 13); corroborated across Malish et al. (2025) and Tashie et al. (2019). Remains partially solved due to coupled convective vs. stratiform storm hyetographs, antecedent soil moisture, and seasonal potential evapotranspir... | Co-located observations of high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge and nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions across Global and Representative Regional Observatories coupl... | partially_solved | multiple_viable_hypotheses | PARTIAL-PROGRESS | true | medium | 3 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-013724",
"UEARTH-013448",
"UEARTH-005593"
] | [
"10.1080/02626667.2019.1620507",
"10.1002/eco.70155",
"10.1002/hyp.13530",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Interfaces in Hydrology (UPH 13), DOI:10.1080/02626667.2019.1620507",
"Malish et al. (2025), Ecohydrology, DOI:10.1002/eco.70155",
"Tashie et al. (2019), Hydrological Processes, DOI:10.1002/hyp.13530",
"B. Arheimer, C. Cudenn... |
UEARTH-000014 | 14 | Long-Term Legacy Contaminant and Nutrient Retention in Catchments (UPH 14) | What biogeochemical and hydrological travel-time mechanisms control the decadal-to-centennial persistence and episodic remobilization of legacy agricultural nutrients and contaminants in catchments? | Why do fertilizers and pollutants remain trapped in soils and groundwater for decades after pollution stops, and what triggers their release? | In agricultural and mixed-use watersheds, how does the coupling between young preferential flow paths, old groundwater age distributions, and vadose-zone geochemical sorption/redox buffers create chemostatic export regimes and multi-decadal lag times (governed by Richards unsaturated flow $\partial_t \theta(\psi) = \na... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | vadose_zone_evapotranspiration_ecohydrology | 2 | [
"mechanism",
"predictability"
] | [
"vadose_zone",
"critical_zone"
] | [
"pore_water",
"soil"
] | [
"hydrological_partitioning_and_runoff",
"ecosystem_disturbance_and_biophysical_feedback"
] | hillslope_to_catchment | Global and Representative Regional Observatories | diurnal_to_synoptic | Holocene | [
"cosmic-ray neutron rover soil moisture, eddy-covariance latent heat fluxes, and xylem/soil water stable isotopes",
"sap-flow sensors, electrical resistivity imaging of root zones, and SMAP/Sentinel-1 microwave soil moisture"
] | [
"partitioning of terrestrial evapotranspiration between plant transpiration (T) and soil/canopy evaporation (E)"
] | [
"Richards unsaturated flow $\\partial_t \\theta(\\psi) = \\nabla \\cdot [K(\\psi) \\nabla (\\psi + z)] - S_{\\mathrm{root}}(\\psi)$ coupled with Penman-Monteith evapotranspiration $\\lambda E = [\\Delta (R_n - G) + \\rho_a c_p \\mathrm{VPD} / r_a] / [\\Delta + \\gamma (1 + r_s / r_a)]$",
"Budyko hydroclimatic par... | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 14); corroborated across Stockinger et al. (2024) and Sousa et al. (2023). Remains open due to coupled vapor pressure deficit (VPD), solar radiation, and intermittent rainfall infiltration pulses and soil water retentio... | Co-located observations of cosmic-ray neutron rover soil moisture, eddy-covariance latent heat fluxes, and xylem/soil water stable isotopes and sap-flow sensors, electrical resistivity imaging of root zones, and SMAP/Sentinel-1 microwave soil moisture across Global and Representative Regional Observatories coupled with... | open | mechanism_known_magnitude_uncertain | OPEN-VERIFIED | true | medium | 3 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-014794",
"UEARTH-013706",
"UEARTH-014964"
] | [
"10.1080/02626667.2019.1620507",
"10.1002/hyp.15038",
"10.3389/feart.2022.886304",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Interfaces in Hydrology (UPH 14), DOI:10.1080/02626667.2019.1620507",
"Stockinger et al. (2024), Hydrological Processes, DOI:10.1002/hyp.15038",
"Sousa et al. (2023), Frontiers in Earth Science, DOI:10.3389/feart.2022.886304",
... |
UEARTH-000015 | 15 | Coevolution of Catchment Geomorphology, Vegetation, and Hydrology (UPH 15) | What thermodynamic optimality or mechanistic feedbacks govern the long-term coevolution of drainage density, soil depth, root-zone storage capacity, and vegetation water use across climate gradients? | How do plants, soils, and river networks shape each other over decades to millennia to control water flow? | Across aridity and tectonic uplift gradients, do vegetation dynamically optimize root-zone water storage capacity ($S_r$) to survive multi-decadal drought return periods, and how does this coevolutionary feedback constrain Budyko water-energy partitioning? | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | catchment_runoff_transit_time_uph | 2 | [
"mechanism",
"feedback"
] | [
"river",
"vadose_zone"
] | [
"freshwater_surface",
"pore_water"
] | [
"hydrological_partitioning_and_runoff",
"groundwater_flow_and_transport"
] | hillslope_to_catchment | Global and Representative Regional Observatories | synoptic_to_seasonal | Anthropocene | [
"high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge",
"nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions"
] | [
"emergent catchment-scale storage-discharge constitutive relations from heterogeneous hillslope preferential flow"
] | [
"Kirchner dynamical catchment storage-discharge sensitivity $g(Q) = dQ/dS = (-dQ/dt) / (Q - P + E)$ and power-law recession $-dQ/dt = a Q^b$",
"master transit-time StorAge Selection (SAS) transport $\\partial_t S_T(T, t) + \\partial_T S_T(T, t) = J(t) - Q(t) \\Omega_Q(S_T, t) - E(t) \\Omega_E(S_T, t)$"
] | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 15); corroborated across Rendilicha et al. (2025) and Murgia et al. (2026). Remains open due to coupled convective vs. stratiform storm hyetographs, antecedent soil moisture, and seasonal potential evapotranspiration an... | Co-located observations of high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge and nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions across Global and Representative Regional Observatories coupl... | open | dominant_hypothesis_unconfirmed | OPEN-VERIFIED | true | hard | 4 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-013408",
"UEARTH-013393",
"UEARTH-005175"
] | [
"10.1080/02626667.2019.1620507",
"10.1016/j.ecolind.2025.113652",
"10.1016/j.jhydrol.2026.135569",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Interfaces in Hydrology (UPH 15), DOI:10.1080/02626667.2019.1620507",
"Rendilicha et al. (2025), Ecological Indicators, DOI:10.1016/j.ecolind.2025.113652",
"Murgia et al. (2026), Journal of Hydrology, DOI:10.1016/j.jhydrol.2026... |
UEARTH-000016 | 16 | Generation and Secular Reversal Mechanics of Earth's Geodynamo (Earth in Time Q1) | How is Earth's magnetic field generated and sustained by thermochemical convection in the liquid iron-nickel outer core, and what magnetohydrodynamic instability triggers geomagnetic excursions and polarity reversals? | How does Earth's liquid outer core generate our planet's magnetic field, and what causes the magnetic poles to flip? | In the rapidly rotating, low-Ekman-number ($\mathrm{Ek} \sim 10^{-15}$), low-magnetic-Prandtl-number ($\mathrm{Pm} \sim 10^{-6}$) liquid outer core, what relative buoyancy contributions from inner-core crystallization latent heat, light-element (Si, O, S, Mg) exsolution, and core-mantle boundary heat-flux heterogeneity... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | core_dynamo_inner_core | 1 | [
"mechanism",
"threshold"
] | [
"inner_core",
"outer_core"
] | [
"core_alloy",
"melt"
] | [
"geomagnetic_dynamo",
"mantle_convection"
] | mantle_or_core_domain | Planetary Deep Interior (Inner and Outer Core) | millennial_to_orbital | Quaternary | [
"PKIKP body-wave travel-time residuals and normal-mode splitting functions",
"satellite and paleomagnetic secular-variation field reconstructions"
] | [
"inner-core crystalline anisotropy, light-element partitioning, and outer-core convective buoyancy flux"
] | [
"magnetic induction $\\partial_t \\mathbf{B} = \\nabla \\times (\\mathbf{u} \\times \\mathbf{B}) + \\eta_m \\nabla^2 \\mathbf{B}$ at $\\mathrm{Ek} \\sim 10^{-15}$ and $\\mathrm{Pm} \\sim 10^{-6}$",
"Elsasser number $\\Lambda = \\sigma B^2 / (\\rho \\Omega) \\sim O(1)$ and thermochemical buoyancy flux $F_B = F_T +... | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, Question 1); corroborated across Fu et al. (2025) and Sun et al. (2023). Remains open due to coupled inner-core crystallization buoyancy flux and secular core cooling and core-mantle boundary topography and heterogeneous lower-mantle thermal ... | Co-located observations of PKIKP body-wave travel-time residuals and normal-mode splitting functions and satellite and paleomagnetic secular-variation field reconstructions across Planetary Deep Interior (Inner and Outer Core) coupled with process-resolving models of geomagnetic dynamo to constrain inner-core crystalli... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-000391",
"UEARTH-001453",
"UEARTH-001704"
] | [
"10.17226/25761",
"10.1029/2025jb031934",
"10.1038/s41467-023-37376-1",
"10.17226/25761"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Priority Questions (Question 1), DOI:10.17226/25761",
"Fu et al. (2025), Journal of Geophysical Research Solid Earth, DOI:10.1029/2025jb031934",
"Sun et al. (2023), Nature Communications, DOI:10.1038/s41467-023-37376-1",
"NASEM (2020), A Vision... |
UEARTH-000017 | 17 | Initiation Timing and Geodynamic Mechanism of Terrestrial Plate Tectonics (Earth in Time Q2) | When and by what lithospheric weakening and mantle-convection mechanism did Earth transition from a stagnant-lid or sluggish-lid regime to global mobile-lid plate tectonics? | When and how did plate tectonics begin on Earth, and why did Earth develop moving plates unlike Venus or Mars? | Across the Hadean-Archean-Proterozoic rock and zircon archive ($4.4\text{--}2.5\,\mathrm{Ga}$), what combination of mantle potential temperature evolution, grain-size damage rheology, plume-induced subduction initiation, and surface water lubrication overcame lithospheric yield strength to establish sustained global su... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | craton_orogen_continental_crust | 1 | [
"mechanism",
"reconstruction"
] | [
"continental_crust",
"orogen"
] | [
"crystalline_rock",
"mantle_silicate"
] | [
"crustal_deformation",
"metamorphic_transformation"
] | tectonic_plate_or_orogen | Archean–Proterozoic Cratons and Continental Orogens | multi_million_year_tectonic | Precambrian | [
"laser-ablation ICP-MS/SIMS zircon U-Pb geochronology and Lu-Hf isotope ratios",
"crustal receiver-function Moho depth maps, Bouguer gravity anomalies, and xenolith thermobarometry"
] | [
"cratonic lithospheric root stability, metasomatic weakening, and orogenic lower-crustal flow"
] | [
"viscous thin-sheet Argand number $\\mathrm{Ar} = g \\rho_c (1 - \\rho_c/\\rho_m) H_c^2 / (\\eta_{\\mathrm{eff}} U_0)$",
"isopycnic cratonic root stability $\\Delta \\rho(T, X_{\\mathrm{Mg\\#}}) = \\rho_0 [ -\\alpha (T - T_0) + \\beta_{\\mathrm{chem}} \\Delta X_{\\mathrm{Mg\\#}} ] \\approx 0$"
] | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, Question 2); corroborated across Korenaga (2011) and Wang et al. (2025). Remains open due to coupled continental collision, lithospheric thickening, and convective removal of eclogitized lower crust and Moho temperature, crustal radiogenic he... | Co-located observations of laser-ablation ICP-MS/SIMS zircon U-Pb geochronology and Lu-Hf isotope ratios and crustal receiver-function Moho depth maps, Bouguer gravity anomalies, and xenolith thermobarometry across Archean–Proterozoic Cratons and Continental Orogens coupled with process-resolving models of crustal defo... | open | active_debate | OPEN-VERIFIED | true | very_hard | 5 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-000330",
"UEARTH-000554",
"UEARTH-000020"
] | [
"10.17226/25761",
"10.1029/2011jb008410",
"10.1038/s43247-025-02973-z",
"10.17226/25761"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Priority Questions (Question 2), DOI:10.17226/25761",
"Korenaga (2011), Journal of Geophysical Research Atmospheres, DOI:10.1029/2011jb008410",
"Wang et al. (2025), Communications Earth & Environment, DOI:10.1038/s43247-025-02973-z",
"NASEM (20... |
UEARTH-000018 | 18 | Thermochemical Nature and Origin of Large Low-Shear-Velocity Provinces (LLSVPs) | Are the two antipodal Large Low-Shear-Velocity Provinces (LLSVPs) beneath Africa and the Pacific purely thermal megaplume clusters, primordial dense bridgmanite/ferropericlase reservoirs, or accumulations of subducted oceanic crust? | What are the two continent-sized blobs deep in Earth's lower mantle beneath Africa and the Pacific, and how did they form? | At the base of the lower mantle ($2,000\text{--}2,891\,\mathrm{km}$ depth), what combination of normal-mode density tomography, S-to-P wave velocity ratios ($d\ln V_S / d\ln V_P$), and noble-gas ($^3\mathrm{He}/^4\mathrm{He}$, $^{182}\mathrm{W}$) plume signatures distinguishes dense thermochemical piles from thermal up... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | lower_mantle_plumes_transition_zone | 1 | [
"mechanism",
"rate"
] | [
"lower_mantle",
"transition_zone"
] | [
"mantle_silicate",
"rock"
] | [
"mantle_convection",
"metamorphic_transformation"
] | mantle_or_core_domain | Global Mantle Transition Zone and Lower Mantle | multi_million_year_tectonic | Cenozoic | [
"broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements",
"full-waveform seismic tomography and P-to-S receiver-function discontinuity depths"
] | [
"thermochemical density contrasts across Large Low-Shear-Velocity Provinces (LLSVPs)"
] | [
"Clapeyron slope $dP/dT = \\Delta S / \\Delta V$ across the $410\\,\\mathrm{km}$ ($\\gamma > 0$) and $660\\,\\mathrm{km}$ ($\\gamma \\le 0$) phase boundaries",
"thermochemical buoyancy ratio $B = \\Delta \\rho_{\\mathrm{chem}} / (\\rho_0 \\alpha \\Delta T)$ and Rayleigh number $\\mathrm{Ra} = \\rho g \\alpha \\De... | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, Question 3a); corroborated across Wang et al. (2020) and Jackson et al. (2018). Remains open due to coupled thermochemical mantle convection and deep slab negative buoyancy and endothermic 660-km phase-transition clapeyron slopes and basal t... | Co-located observations of broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements and full-waveform seismic tomography and P-to-S receiver-function discontinuity depths across Global Mantle Transition Zone and Lower Mantle coupled with process-resolving models of mantle conve... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-001403",
"UEARTH-000311",
"UEARTH-002760"
] | [
"10.17226/25761",
"10.1038/s41467-019-13720-2",
"10.1029/2018gc007552",
"10.17226/25761"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Deep Earth Structure (Question 3a), DOI:10.17226/25761",
"Wang et al. (2020), Nature communications, DOI:10.1038/s41467-019-13720-2",
"Jackson et al. (2018), Geochemistry Geophysics Geosystems, DOI:10.1029/2018gc007552",
"NASEM (2020), A Vision... |
UEARTH-000019 | 19 | Rheological Controls on the Lithosphere-Asthenosphere Boundary (LAB) | What relative roles do partial silicate melt fractions, grain-boundary water weakening, and elastically accommodated grain-boundary sliding play in producing the sharp seismic velocity drop and low viscosity at the oceanic Lithosphere-Asthenosphere Boundary? | What makes the boundary between Earth's rigid tectonic plates and the softer mantle beneath them so sharp and slippery? | Beneath oceanic plates of varying thermal age ($0\text{--}150\,\mathrm{Ma}$), can broadband ocean-bottom magnetotelluric, receiver-function ($Sp$, $Ps$), and active-source seismic reflection profiles distinguish a volatile-rich partial melt channel from sub-solidus dislocation/diffusion creep transitions at the LAB? | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | subduction_slab_mantle_wedge | 3 | [
"mechanism",
"rate"
] | [
"subduction_zone",
"upper_mantle"
] | [
"crystalline_rock",
"magma_or_melt"
] | [
"plate_subduction",
"magma_generation_and_ascent"
] | tectonic_plate_or_orogen | Circum-Pacific and Tethyan Subduction Margins | multi_million_year_tectonic | Cenozoic | [
"deep magnetotelluric (MT) and electrical resistivity tomography (ERT) conductivity inversions",
"high-resolution slab-interface seismic attenuation and magnetotelluric conductivity profiles"
] | [
"mechanical coupling and metamorphic dehydration kinetics along the plate interface"
] | [
"composite dislocation-diffusion creep $\\dot{\\varepsilon}_{ij} = (A_{\\mathrm{dis}} \\tau_E^{n-1} + A_{\\mathrm{diff}} d^{-p}) C_{\\mathrm{OH}}^r \\exp[-(E^* + P V^*)/RT] \\tau_{ij}$",
"slab thermal parameter $\\Phi_{\\mathrm{slab}} = t_{\\mathrm{age}} v_{\\mathrm{conv}} \\sin\\theta$ governing dehydration reac... | Formulated in Exploring Earth by Scientific Ocean Drilling: 2050 Science Framework (2020, SO-2); corroborated across Wang et al. (2024) and Rychert et al. (2005). Remains open due to coupled slab pull, trench rollback, and metamorphic dehydration reactions and slab thermal age, incoming plate hydration state, and overr... | Co-located observations of deep magnetotelluric (MT) and electrical resistivity tomography (ERT) conductivity inversions and high-resolution slab-interface seismic attenuation and magnetotelluric conductivity profiles across Circum-Pacific and Tethyan Subduction Margins coupled with process-resolving models of plate su... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,020 | A. A. P. Koppers, R. Coggon | 2026-10-16T00:00:00 | [
"UEARTH-000605",
"UEARTH-000573",
"UEARTH-000082"
] | [
"10.6075/J0W66J9H",
"10.1038/s41467-024-47887-0",
"10.1038/nature03904",
"10.17226/25761"
] | [
"Exploring Earth by Scientific Ocean Drilling: 2050 Science Framework (2020), Oceanic Life Cycle of Tectonic Plates (SO-2), DOI:10.6075/J0W66J9H",
"Wang et al. (2024), Nature Communications, DOI:10.1038/s41467-024-47887-0",
"Rychert et al. (2005), Nature, DOI:10.1038/nature03904",
"NASEM (2020), A Vision for ... |
UEARTH-000020 | 20 | Nucleation to Arrest Physics of Large Earthquakes and Fault Slip Modes (Earth in Time Q4) | What physical, frictional, and pore-fluid processes govern the transition from aseismic creep and slow slip events to dynamic seismic rupture nucleation, propagation, and arrest on natural faults? | What determines whether a tectonic fault creeps harmlessly or ruptures in a devastating earthquake, and what stops an earthquake once it starts? | Along heterogeneous subduction megathrusts and continental strike-slip faults, how do rate-and-state friction parameters ($a-b$), dilatant pore-pressure transients, thermal pressurization, and geometrical fault roughness interact across millimeter-to-kilometer scales to control rupture nucleation size and final seismic... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | earthquake_rupture_fault_mechanics | 1 | [
"mechanism",
"hazard_generation"
] | [
"fault_zone",
"continental_crust"
] | [
"crystalline_rock",
"pore_water"
] | [
"fault_rupture_and_slip",
"crustal_deformation"
] | fault_or_volcanic_edifice | Plate-Boundary and Intraplate Seismogenic Fault Zones | instantaneous_to_event | Holocene | [
"near-field broadband seismograms, high-rate GNSS displacements, and InSAR coseismic interferograms",
"fault-zone drilling core microstructure and laboratory rotary-shear friction velocity dependence"
] | [
"rate-and-state frictional healing, dynamic pore-fluid pressurization, and rupture arrest thresholds"
] | [
"rate-and-state friction $\\tau = \\sigma_n' [\\mu_0 + a \\ln(V/V_0) + b \\ln(V_0 \\theta / D_c)]$ with thermal pressurization $\\partial_t P_f = \\Lambda_{\\mathrm{TP}} \\tau V / w + D_{\\mathrm{hyd}} \\partial_{yy} P_f$",
"elastodynamic fracture energy balance $G_c = \\int_0^{D_c} (\\tau(u) - \\tau_r) du$ and c... | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, Question 4a); corroborated across Lengliné et al. (2023) and Passelègue et al. (2019). Remains open due to coupled tectonic shear-stress loading and coseismic dynamic pore-pressure transients and fault-zone geometric complexity, gouge mineral... | Co-located observations of near-field broadband seismograms, high-rate GNSS displacements, and InSAR coseismic interferograms and fault-zone drilling core microstructure and laboratory rotary-shear friction velocity dependence across Plate-Boundary and Intraplate Seismogenic Fault Zones coupled with process-resolving m... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-001610",
"UEARTH-001540",
"UEARTH-000364"
] | [
"10.17226/25761",
"10.1029/2022gl101604",
"10.1130/g45868.1",
"10.25740/hy589fc7561"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Priority Questions (Question 4a), DOI:10.17226/25761",
"Lengliné et al. (2023), Geophysical Research Letters, DOI:10.1029/2022gl101604",
"Passelègue et al. (2019), Geology, DOI:10.1130/g45868.1",
"E. E. Brodsky, T. A. Plank, D. M. Roman et al. ... |
UEARTH-000021 | 21 | Transcrustal Magma Storage Architecture and Eruption Triggering Precursors (ERUPT Grand Challenge 1) | How do crystal-rich transcrustal magma mush systems rapidly remobilize into eruptible melt lenses, and what geophysical or volatile-degassing precursors distinguish impending eruptions from failed magmatic intrusions? | How does mostly solid magma deep underground suddenly turn liquid and erupt, and why do some volcanic unrest episodes stop without erupting? | Within transcrustal silicic and mafic magmatic plumbing systems ($2\text{--}30\,\mathrm{km}$ depth), what coupled thermo-mechanical thresholds of mafic recharge, second boiling volatile exsolution, and mush compaction govern eruption onset, and how can joint InSAR, seismic tomography, and $\mathrm{CO}_2/\mathrm{SO}_2$ ... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | volcanic_plumbing_eruption_degassing | 1 | [
"mechanism",
"hazard_generation"
] | [
"magma_reservoir",
"continental_crust"
] | [
"magma_or_melt",
"hydrothermal_fluid"
] | [
"volcanic_degassing_and_eruption",
"magma_generation_and_ascent"
] | fault_or_volcanic_edifice | Active Arc, Rift, and Hotspot Volcanic Systems | instantaneous_to_event | Anthropocene | [
"multi-temporal InSAR surface displacement velocity fields and continuous GNSS station networks",
"broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements"
] | [
"volatile exsolution kinetics and overpressure thresholds triggering dike propagation"
] | [
"multiphase magma viscosity $\\eta(\\phi_c, C_{\\mathrm{H2O}}, T) = \\eta_{\\mathrm{melt}}(C_{\\mathrm{H2O}}, T) (1 - \\phi_c / \\phi_m)^{-B \\phi_m}$ and Deborah fragmentation criterion $\\mathrm{De} = \\eta \\dot{\\gamma} / G_\\infty \\ge 10^{-2}$",
"conduit momentum-continuity balance $\\rho_m u \\partial_z u ... | Formulated in Volcanic Eruptions and Their Repose, Unrest, Precursors, and Timing (ERUPT) (2017, GC-1); corroborated across Scudero et al. (2019) and Girona et al. (2015). Remains open due to coupled mafic magma recharge, volatile exsolution buoyancy, and conduit shear heating and magma viscosity, conduit geometry, and... | Co-located observations of multi-temporal InSAR surface displacement velocity fields and continuous GNSS station networks and broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements across Active Arc, Rift, and Hotspot Volcanic Systems coupled with process-resolving models of ... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,017 | Committee on Improving Understanding of Volcanic Eruptions, M. Manga (Chair) | 2026-10-16T00:00:00 | [
"UEARTH-001545",
"UEARTH-001600",
"UEARTH-000367"
] | [
"10.17226/24650",
"10.1038/s41598-019-40563-0",
"10.1038/srep18212",
"10.25740/hy589fc7561"
] | [
"Volcanic Eruptions and Their Repose, Unrest, Precursors, and Timing (ERUPT) (2017), Grand Challenges in Volcano Science (GC-1), DOI:10.17226/24650",
"Scudero et al. (2019), Scientific Reports, DOI:10.1038/s41598-019-40563-0",
"Girona et al. (2015), Scientific reports, DOI:10.1038/srep18212",
"E. E. Brodsky, ... |
UEARTH-000022 | 22 | Up-Dip Rupture Propagation and Tsunamigenesis on Shallow Subduction Megathrusts (SZ4D FEC) | Under what frictional, wedge-compliance, and fluid-overpressure conditions does a subduction megathrust earthquake propagate through the nominally velocity-strengthening shallow trench wedge to generate an outsized tsunami? | Why do some subduction earthquakes break all the way to the seafloor trench and trigger massive tsunamis when shallow sediments should resist seismic slip? | In the shallowest $0\text{--}15\,\mathrm{km}$ of subduction interfaces, how do dynamic weakening (thermal pressurization of low-permeability clay-rich décollements), inelastic outer-wedge splay faulting, and inelastic seafloor uplift govern tsunami excitation during $M_w \ge 8.5$ megathrust ruptures? | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | tsunami_seafloor_displacement | 3 | [
"mechanism",
"hazard_generation"
] | [
"seafloor",
"coast"
] | [
"seawater",
"marine_sediment"
] | [
"fault_rupture_and_slip",
"coastal_and_estuarine_morphodynamics"
] | ocean_basin_or_gyre | Tsunamigenic Subduction Trenches and Coastal Margins | instantaneous_to_event | Holocene | [
"DART deep-ocean bottom pressure records, cabled seafloor observatories, and tide-gauge waveforms",
"post-tsunami coastal runup surveys, boulder transport limits, and paleotsunami sand sheets"
] | [
"shallow trench-wedge splay-fault slip partitioning and tsunami-earthquake dispersive wave amplification"
] | [
"dispersive Boussinesq shallow-water wave propagation $\\partial_t \\eta + \\nabla \\cdot [(h + \\eta)\\mathbf{u}] = \\partial_t \\zeta_{\\mathrm{seafloor}}$ with phase speed $c = \\sqrt{g h (1 - k^2 h^2 / 3)}$",
"Okada elastic/inelastic coseismic vertical seafloor uplift $u_z(x,y)$ amplifying shallow trench slip... | Formulated in SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022, FEC-Q2); corroborated across Yanagisawa et al. (2016) and Qiu et al. (2019). Remains open due to coupled coseismic seafloor vertical displacement and submarine mass-failure acceleration and continental shelf bathymetry, coastal topograph... | Co-located observations of DART deep-ocean bottom pressure records, cabled seafloor observatories, and tide-gauge waveforms and post-tsunami coastal runup surveys, boulder transport limits, and paleotsunami sand sheets across Tsunamigenic Subduction Trenches and Coastal Margins coupled with process-resolving models of ... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,022 | E. E. Brodsky, T. A. Plank | 2026-10-16T00:00:00 | [
"UEARTH-002506",
"UEARTH-001816",
"UEARTH-000479"
] | [
"10.25740/hy589fc7561",
"10.1002/2015jb012617",
"10.5194/nhess-19-1565-2019",
"10.25740/hy589fc7561"
] | [
"SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022), Faulting and Earthquake Cycles (FEC-Q2), DOI:10.25740/hy589fc7561",
"Yanagisawa et al. (2016), Journal of Geophysical Research Solid Earth, DOI:10.1002/2015jb012617",
"Qiu et al. (2019), Natural hazards and earth system sciences, DOI:10.5194... |
UEARTH-000023 | 23 | Deep Earth Cycling and Partitioning of Critical Elements and Volatiles (Earth in Time Q3) | What thermodynamic, redox, and mineral-fluid partitioning mechanisms govern the distribution, deep-mantle recycling, and crustal concentration of critical elements and volatiles (H, C, N, S, halogens) through Earth history? | How do water, carbon, sulfur, and critical metals cycle between Earth's surface and deep interior to form concentrated mineral deposits? | Across subduction dehydration, mantle-wedge metasomatism, and transcrustal magmatic-hydrothermal differentiation, how do oxygen fugacity ($f\mathrm{O}_2$), sulfur speciation ($\mathrm{S}^{2-}/\mathrm{S}^{6+}$), and supercritical fluid-melt partition coefficients control the deep volatile budget and porphyry/epithermal ... | geochemistry_mineralogy_petrology_earth_materials | 3 | Geochemistry, Mineralogy, Petrology, and Earth Materials | hydrothermal_ore_deposits_metallogeny | 1 | [
"mechanism",
"budget"
] | [
"hydrothermal_system",
"continental_crust"
] | [
"hydrothermal_fluid",
"crystalline_rock"
] | [
"redox_transformation",
"magma_generation_and_ascent"
] | core_to_outcrop | Magmatic–Hydrothermal and Submarine Metallogenic Belts | multi_million_year_tectonic | Cenozoic | [
"fluid-inclusion microthermometry, Raman spectroscopy, and LA-ICP-MS single-inclusion metal assays",
"in-situ sulfur, oxygen, and copper/iron/zinc stable isotope zoning across ore paragenetic stages"
] | [
"magmatic-hydrothermal fluid flux budgets and structural permeability focusing mechanisms"
] | [
"fluid-melt metal partitioning $D_M^{\\mathrm{fluid/melt}}(P, T, X_{\\mathrm{Cl}}, X_{\\mathrm{S}}, f\\mathrm{O}_2)$ and Helgeson-Kirkham-Flowers log $K(T, \\rho_w)$",
"chalcophile sulfide-silicate partitioning $D_{\\mathrm{Cu,Au}}^{\\mathrm{sulf/sil}} \\sim 10^3\\text{--}10^5$ vs. volatile saturation timing"
] | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, Question 3); corroborated across Wang et al. (2026) and Liang et al. (2024). Remains open due to coupled magmatic fluid exsolution, decompression boiling, and fluid-rock redox reactions and host-rock buffering capacity, fault-fracture network... | Co-located observations of fluid-inclusion microthermometry, Raman spectroscopy, and LA-ICP-MS single-inclusion metal assays and in-situ sulfur, oxygen, and copper/iron/zinc stable isotope zoning across ore paragenetic stages across Magmatic–Hydrothermal and Submarine Metallogenic Belts coupled with process-resolving m... | open | mechanism_known_magnitude_uncertain | OPEN-VERIFIED | true | medium | 3 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-002583",
"UEARTH-002800",
"UEARTH-003767"
] | [
"10.17226/25761",
"10.1038/s41467-026-74619-3",
"10.2138/am-2023-9217",
"10.6075/J0W66J9H"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Priority Questions (Question 3), DOI:10.17226/25761",
"Wang et al. (2026), Nature communications, DOI:10.1038/s41467-026-74619-3",
"Liang et al. (2024), American Mineralogist, DOI:10.2138/am-2023-9217",
"A. A. P. Koppers and R. Coggon (Eds.) (2... |
UEARTH-000024 | 24 | Serpentinization Kinetics and Abiotic Hydrogen-Methane Fluxes in Ultramafic Oceanic Lithosphere | What mineralogical, temperature, and fluid-pathway controls govern the rate of peridotite serpentinization, magnetite catalysis, and abiotic $\mathrm{H}_2$ and $\mathrm{CH}_4$ production in slow-spreading oceanic lithosphere and forearc mantles? | What controls the rate at which seawater reacts with mantle rocks to produce hydrogen and abiotic methane beneath the seafloor? | At $50\text{--}400\,^\circ\mathrm{C}$ inabyssal peridotites and subduction forearcs, how does reaction-induced cracking versus pore-space clogging interact with iron partitioning between brucite, serpentine, and magnetite to regulate $\mathrm{H}_2$ generation and Fischer-Tropsch-type carbon reduction? | geochemistry_mineralogy_petrology_earth_materials | 3 | Geochemistry, Mineralogy, Petrology, and Earth Materials | igneous_petrology_magmatic_differentiation | 3 | [
"mechanism",
"rate"
] | [
"magma_reservoir",
"continental_crust"
] | [
"magma_or_melt",
"crystalline_rock"
] | [
"magma_generation_and_ascent",
"metamorphic_transformation"
] | core_to_outcrop | Crustal and Upper-Mantle Magmatic Provinces | multi_million_year_tectonic | Cenozoic | [
"electron microprobe and LA-ICP-MS mineral/melt-inclusion major and trace element zoning",
"piston-cylinder and multi-anvil phase-equilibrium experiments and radiogenic Sr-Nd-Hf isotopes"
] | [
"degree of partial melting, crustal assimilation vs. fractional crystallization (AFC) mass balance"
] | [
"open-system assimilation-fractional crystallization (AFC) $dC_m/dF = [r/(r-1)] C_a / F - D_{\\mathrm{bulk}} C_m / F$ and oxygen fugacity $\\Delta \\mathrm{FMQ}$",
"McKenzie compaction length $\\delta_c = \\sqrt{k_\\phi (\\zeta + 4\\eta/3) / \\mu_f}$ governing melt extraction from crystal mush"
] | Formulated in Exploring Earth by Scientific Ocean Drilling: 2050 Science Framework (2020, SO-1); corroborated across Huang et al. (2017) and Zhang et al. (2023). Remains open due to coupled decompression melting, mantle heat flux, and flux melting by slab-derived volatiles and source rock fertility, oxygen fugacity (fO... | Co-located observations of electron microprobe and LA-ICP-MS mineral/melt-inclusion major and trace element zoning and piston-cylinder and multi-anvil phase-equilibrium experiments and radiogenic Sr-Nd-Hf isotopes across Crustal and Upper-Mantle Magmatic Provinces coupled with process-resolving models of magma generati... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | medium | 3 | 2,020 | A. A. P. Koppers, R. Coggon | 2026-10-16T00:00:00 | [
"UEARTH-002611",
"UEARTH-002579",
"UEARTH-000450"
] | [
"10.6075/J0W66J9H",
"10.1016/j.gsf.2017.01.001",
"10.1093/nsr/nwac207",
"10.6075/J0W66J9H"
] | [
"Exploring Earth by Scientific Ocean Drilling: 2050 Science Framework (2020), Habitability and Life on Earth (SO-1), DOI:10.6075/J0W66J9H",
"Huang et al. (2017), Geoscience Frontiers, DOI:10.1016/j.gsf.2017.01.001",
"Zhang et al. (2023), National science review, DOI:10.1093/nsr/nwac207",
"A. A. P. Koppers and... |
UEARTH-000025 | 25 | Equable High-Latitude Warmth and Meridional Temperature Gradients in Hothouse Climates | What radiative, cloud-microphysical, or ocean-atmosphere heat-transport mechanisms sustained ice-free polar warmth and reduced meridional sea-surface temperature gradients during Early Eocene and Cretaceous hothouse climates? | How did Earth's poles stay warm enough for crocodiles and palm trees during ancient greenhouse climates without overheating the tropics? | During the Early Eocene Climatic Optimum ($\sim 53\text{--}49\,\mathrm{Ma}$, $\mathrm{CO}_2 \sim 1,000\text{--}1,600\,\mathrm{ppm}$), does reconciling clumped-isotope ($\Delta_{47}$), $\mathrm{TEX}_{86}$, and $\delta^{18}\mathrm{O}$ SST proxies with Earth system models require optically thinner polar stratocumulus clou... | geologic_time_paleoclimate_stratigraphy_earth_history | 4 | Geologic Time, Paleoclimate, Stratigraphy, and Earth History | greenhouse_hyperthermals_cenozoic_mesozoic | 8 | [
"mechanism",
"transport"
] | [
"sedimentary_stratigraphic_archive",
"marine_sediment"
] | [
"marine_sediment",
"sedimentary_rock"
] | [
"carbon_cycle_and_biogeochemical_cycling",
"radiative_transfer_and_energy_balance"
] | planetary_global | Global and Representative Regional Observatories | multi_million_year_tectonic | Mesozoic | [
"IODP deep-sea core carbon-isotope excursions (CIEs), clumped-isotope (Delta47) paleothermometry, and boron-isotope pCO2",
"cyclo- and magnetostratigraphic age models and osmium/strontium weathering-proxy records"
] | [
"silicate-weathering and organic-carbon burial negative feedback timescales following carbon-cycle perturbations"
] | [
"carbon-cycle isotope mass balance $\\Delta \\delta^{13}\\mathrm{C}_{\\mathrm{ex}} = M_{\\mathrm{emit}} (\\delta^{13}\\mathrm{C}_{\\mathrm{src}} - \\delta^{13}\\mathrm{C}_0) / (M_0 + M_{\\mathrm{emit}})$ and Walker silicate weathering $F_{\\mathrm{sil}} \\propto p\\mathrm{CO}_2^\\beta \\exp(\\Delta T / T_e)$",
"E... | Formulated in Past climates inform our future (2020, Section 2); corroborated across Harper et al. (2024) and Hovikoski et al. (2021). Remains open due to coupled Large Igneous Province (LIP) volcanic degassing, methane hydrate dissociation, and gateway tectonics and paleogeographic continental configuration, ocean gat... | Co-located observations of IODP deep-sea core carbon-isotope excursions (CIEs), clumped-isotope (Delta47) paleothermometry, and boron-isotope pCO2 and cyclo- and magnetostratigraphic age models and osmium/strontium weathering-proxy records across Global and Representative Regional Observatories coupled with process-res... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,020 | Jessica E. Tierney, Christopher J. Poulsen | 2026-10-16T00:00:00 | [
"UEARTH-000109",
"UEARTH-003931",
"UEARTH-007923"
] | [
"10.1126/science.aay3701",
"10.1073/pnas.2318779121",
"10.1038/s43247-021-00249-w",
"10.1126/science.aay3701"
] | [
"Past climates inform our future (2020), Hothouse Climates (Section 2), DOI:10.1126/science.aay3701",
"Harper et al. (2024), Proceedings of the National Academy of Sciences of the United States of America, DOI:10.1073/pnas.2318779121",
"Hovikoski et al. (2021), Communications Earth & Environment, DOI:10.1038/s4... |
UEARTH-000026 | 26 | Biogeochemical Controls on the Proterozoic Atmospheric Oxygen Stasis and Neoproterozoic Oxygenation | What coupled phosphorus-iron-sulfur feedbacks maintained atmospheric oxygen at low levels ($0.1\text{--}10\%$ PAL) throughout the mid-Proterozoic 'Boring Billion', and what tectonic or biological trigger drove the Neoproterozoic Oxygenation Event? | Why did Earth's atmospheric oxygen stay low for over a billion years after the first oxygenation event before rising enough to support animal life? | Between $1.8\,\mathrm{Ga}$ and $0.8\,\mathrm{Ga}$, how did ferruginous/euxinic deep-ocean phosphorus scavenging, terrestrial oxidative weathering efficiency, and organic carbon burial fractions ($f_{\mathrm{org}}$ constrained by $\delta^{13}\mathrm{C}$ and $\delta^{53}\mathrm{Cr}$) stabilize low atmospheric $p\mathrm{O... | geologic_time_paleoclimate_stratigraphy_earth_history | 4 | Geologic Time, Paleoclimate, Stratigraphy, and Earth History | precambrian_oxygenation_early_earth | 8 | [
"mechanism",
"reconstruction"
] | [
"sedimentary_stratigraphic_archive",
"atmosphere"
] | [
"sedimentary_rock",
"marine_sediment"
] | [
"redox_transformation",
"carbon_cycle_and_biogeochemical_cycling"
] | planetary_global | Global and Representative Regional Observatories | billion_year_planetary | Precambrian | [
"mass-independent sulfur isotopes (Delta33S), iron speciation, and Ce/Mo/U/Cr redox-sensitive trace-metal shales",
"carbonate-associated sulfate and detrital redox-sensitive mineral assemblages"
] | [
"stepwise oxygenation of Earth's atmosphere and deep oceans across the GOE and NOE"
] | [
"global redox-carbon burial balance $F_{\\mathrm{O2,source}} = F_{\\mathrm{total\\,C}} \\cdot f_{\\mathrm{org}}(\\delta^{13}\\mathrm{C}) + F_{\\mathrm{pyr}} - F_{\\mathrm{volc\\,red}} - F_{\\mathrm{ox\\,weath}}(p\\mathrm{O}_2)$",
"planetary radiative balance $(S_\\odot(t)/4)(1 - A_p) = \\mathrm{OLR}(T_s, p\\mathr... | Formulated in The rise of oxygen in Earth's early ocean and atmosphere (2014, Section 3); corroborated across Hou et al. (2025) and Krause et al. (2022). Remains open due to coupled oxygenic photosynthesis evolution, mantle reducer outgassing decline, and Snowball Earth glaciations and continental emergence area, marin... | Co-located observations of mass-independent sulfur isotopes (Delta33S), iron speciation, and Ce/Mo/U/Cr redox-sensitive trace-metal shales and carbonate-associated sulfate and detrital redox-sensitive mineral assemblages across Global and Representative Regional Observatories coupled with process-resolving models of re... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,014 | Timothy W. Lyons, Christopher T. Reinhard | 2026-10-16T00:00:00 | [
"UEARTH-004937",
"UEARTH-004964",
"UEARTH-012519"
] | [
"10.1038/nature13068",
"10.1029/2025jg008835",
"10.1126/sciadv.abm8191",
"10.1126/science.aay3701"
] | [
"The rise of oxygen in Earth's early ocean and atmosphere (2014), Proterozoic Redox Evolution (Section 3), DOI:10.1038/nature13068",
"Hou et al. (2025), Journal of Geophysical Research Biogeosciences, DOI:10.1029/2025jg008835",
"Krause et al. (2022), Science Advances, DOI:10.1126/sciadv.abm8191",
"J. E. Tiern... |
UEARTH-000027 | 27 | Reciprocal Coupling Between Tectonic Uplift, Erosion, and Climate Evolution (Earth in Time Q5) | Do Cenozoic mountain building, monsoon intensification, and glacial valley incision drive global silicate weathering cooling, or does late-Cenozoic climatic cooling and precipitation variability primarily accelerate mountain erosion? | Do rising mountain ranges cool Earth's climate by eroding rock, or does a cooling, stormier climate speed up the erosion of mountains? | Over $10^5\text{--}10^7\,\mathrm{yr}$ timescales in active orogens (Himalaya-Tibet, Andes, Southern Alps), how can detrital thermochronology, cosmogenic nuclide ($^{10}\mathrm{Be}$, $^{26}\mathrm{Al}$) denudation rates, and lithium/osmium marine isotope records resolve the causal direction between tectonic rock uplift,... | geomorphology_sediments_surface_processes | 5 | Geomorphology, Sediments, and Surface Processes | tectonic_geomorphology_orogenic_erosion | 1 | [
"mechanism",
"reconstruction"
] | [
"orogen",
"river"
] | [
"crystalline_rock",
"fluvial_or_coastal_sediment"
] | [
"physical_erosion_and_denudation",
"crustal_deformation"
] | tectonic_plate_or_orogen | Himalaya–Tibetan Plateau and Central Asian Orogenic System | millennial_to_orbital | Cenozoic | [
"in-situ terrestrial cosmogenic nuclide (10Be, 26Al) surface exposure and denudation inventories",
"catchment-wide cosmogenic 10Be denudation rates, low-temperature apatite (U-Th)/He ages, and channel steepness (ksn)"
] | [
"transient landscape response to drainage reorganization and glacial-fluvial erosion switching"
] | [
"stream-power incision and hillslope diffusion $\\partial_t z = U(x,y) - K A^m |\\nabla z|^n + D \\nabla^2 z$ and integral $\\chi = \\int_{x_b}^x (A_0/A(x'))^{m/n} dx'$",
"cosmogenic $^{10}\\mathrm{Be}$ steady-state denudation $N_{10} = P_0 / (\\lambda_{10} + \\rho_r \\varepsilon / \\Lambda_{\\mathrm{atten}})$"
] | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, Question 5); corroborated across Kim et al. (2022) and Wang et al. (2020). Remains open due to coupled tectonic rock uplift, orographic precipitation focus, and Quaternary glaciation cycles and bedrock lithological erodibility, fracture spaci... | Co-located observations of in-situ terrestrial cosmogenic nuclide (10Be, 26Al) surface exposure and denudation inventories and catchment-wide cosmogenic 10Be denudation rates, low-temperature apatite (U-Th)/He ages, and channel steepness (ksn) across Himalaya–Tibetan Plateau and Central Asian Orogenic System coupled wi... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-006035",
"UEARTH-005957",
"UEARTH-002152"
] | [
"10.17226/25761",
"10.1080/04353676.2022.2121998",
"10.2113/2020/7866972",
"10.1038/s43017-021-00253-w"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Priority Questions (Question 5), DOI:10.17226/25761",
"Kim et al. (2022), Geografiska Annaler Series A Physical Geography, DOI:10.1080/04353676.2022.2121998",
"Wang et al. (2020), Lithosphere, DOI:10.2113/2020/7866972",
"J. Syvitski, J. R. Ánge... |
UEARTH-000028 | 28 | Source-to-Sink Sediment Buffering and Lag Times Across Alluvial Floodplains | How do alluvial floodplain storage, channel avulsion frequency, and grain-size fining buffer and delay the transmission of upland tectonic and anthropogenic erosion signals to continental margins? | How long do rivers store eroded sediment on floodplains before delivering it to deltas and the ocean, and how does this hide upstream erosion changes? | In large source-to-sink river systems ($L > 10^2\text{--}10^3\,\mathrm{km}$), what controls the nonlinear diffusive mass-transfer timescale ($\tau_{\mathrm{eq}} \sim L^2 / \kappa_s$) and how does dam trapping plus floodplain exchange mask hydroclimatic sediment pulses? | geomorphology_sediments_surface_processes | 5 | Geomorphology, Sediments, and Surface Processes | fluvial_channel_sediment_transport | 7 | [
"mechanism",
"budget"
] | [
"river",
"floodplain"
] | [
"fluvial_or_coastal_sediment",
"freshwater_surface"
] | [
"sediment_transport_and_deposition",
"physical_erosion_and_denudation"
] | reach | Global and Representative Regional Observatories | interannual_to_decadal | Holocene | [
"acoustic Doppler bedload/suspended-flux profiles, repeat airborne LiDAR/bathymetric DEMs, and grain-size distributions",
"in-situ cosmogenic nuclide (10Be/26Al) catchment erosion rates and fallout radionuclide (137Cs/210Pb) budgets"
] | [
"nonlinear bedload transport thresholds, channel-width adjustment laws, and avulsion return periods"
] | [
"Shields dimensionless bed shear stress $\\tau^* = \\tau_b / [(\\rho_s - \\rho_w) g D_{50}] \\ge \\tau^*_c$ and Exner conservation $(1 - \\lambda_p) \\partial_t \\eta = -\\nabla \\cdot \\mathbf{q}_b$",
"Rouse suspended sediment concentration profile $C(z)/C_a = [(h-z)/z \\cdot a/(h-a)]^{\\mathrm{Ro}}$ where $\\ma... | Formulated in Earth's sediment cycle during the Anthropocene (2022, Section 4); corroborated across D’Arcy et al. (2016) and Liu et al. (2025). Remains open due to coupled flood hydrograph flashiness, tectonic base-level fall, and upstream sediment supply pulses and bed grain-size armoring, riparian bank cohesion, and ... | Co-located observations of acoustic Doppler bedload/suspended-flux profiles, repeat airborne LiDAR/bathymetric DEMs, and grain-size distributions and in-situ cosmogenic nuclide (10Be/26Al) catchment erosion rates and fallout radionuclide (137Cs/210Pb) budgets across Global and Representative Regional Observatories coup... | open | scale_dependent_disagreement | OPEN-VERIFIED | true | medium | 3 | 2,022 | Jaia Syvitski, Juan Restrepo Ángel | 2026-10-16T00:00:00 | [
"UEARTH-005349",
"UEARTH-005139",
"UEARTH-013816"
] | [
"10.1038/s43017-021-00253-w",
"10.1111/sed.12308",
"10.1038/s41598-025-11451-7",
"10.1038/s43017-021-00253-w"
] | [
"Earth's sediment cycle during the Anthropocene (2022), Anthropocene Sediment Cycle (Section 4), DOI:10.1038/s43017-021-00253-w",
"D’Arcy et al. (2016), Sedimentology, DOI:10.1111/sed.12308",
"Liu et al. (2025), Scientific Reports, DOI:10.1038/s41598-025-11451-7",
"J. Syvitski, J. R. Ángel, Y. Saito et al. (2... |
UEARTH-000029 | 29 | Physical Mechanisms of Convective Self-Aggregation in the Tropical Atmosphere (WCRP Q1) | What radiative, surface-flux, and cold-pool moisture feedbacks control convective self-aggregation in the real tropical atmosphere, and how does aggregation modulate tropical tropospheric humidity and outgoing longwave radiation? | What causes tropical thunderstorms to cluster together into organized systems, and how does that clustering dry out the surrounding atmosphere? | Across mesoscale-to-planetary tropical domains, how do longwave radiative cooling contrasts between dry subsiding regions and moist anvil clouds interact with boundary-layer cold pools and sea-surface temperature gradients to drive convective organization (governed by column moist static energy budget $\langle \partial... | atmosphere_weather_atmospheric_chemistry | 6 | Atmosphere, Weather, and Atmospheric Chemistry | convective_storms_tropical_cyclones_monsoon | 4 | [
"mechanism",
"budget"
] | [
"troposphere",
"boundary_layer"
] | [
"tropospheric_air",
"precipitation"
] | [
"atmospheric_convection_and_circulation",
"cloud_microphysics_and_aerosol_interaction"
] | regional_synoptic | Global and Representative Regional Observatories | diurnal_to_synoptic | Anthropocene | [
"phased-array and dual-polarization weather radar, dropsonde wind/thermodynamic profiles, and geostationary IR/lightning imagers",
"cloud-resolving (km-scale) ensemble hindcasts and airborne Doppler radar vorticity retrievals"
] | [
"stochastic boundary-layer trigger mechanisms for deep moist convection initiation over complex terrain"
] | [
"convective available potential energy $\\mathrm{CAPE} = \\int_{\\mathrm{LFC}}^{\\mathrm{EL}} g (\\theta_{v,\\mathrm{parcel}} - \\theta_{v,\\mathrm{env}})/\\theta_{v,\\mathrm{env}} dz$ and entraining plume mass flux $\\partial_z \\ln M = \\varepsilon - \\delta$",
"column moist static energy budget $\\langle \\par... | Formulated in Clouds, circulation and climate sensitivity (2015, Box 1 Question 1); corroborated across Muller et al. (2018) and Lutsko et al. (2018). Remains open due to coupled convective available potential energy (CAPE), sea-surface enthalpy fluxes, and vertical wind shear and mid-tropospheric dry-air entrainment, ... | Co-located observations of phased-array and dual-polarization weather radar, dropsonde wind/thermodynamic profiles, and geostationary IR/lightning imagers and cloud-resolving (km-scale) ensemble hindcasts and airborne Doppler radar vorticity retrievals across Global and Representative Regional Observatories coupled wit... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,015 | S. Bony, B. Stevens | 2026-10-16T00:00:00 | [
"UEARTH-000190",
"UEARTH-006337",
"UEARTH-000218"
] | [
"10.1038/ngeo2398",
"10.1073/pnas.1719967115",
"10.1029/2018ms001482",
"10.1029/2019RG000678"
] | [
"Clouds, circulation and climate sensitivity (2015), Guiding Questions (Box 1 Question 1), DOI:10.1038/ngeo2398",
"Muller et al. (2018), Proceedings of the National Academy of Sciences of the United States of America, DOI:10.1073/pnas.1719967115",
"Lutsko et al. (2018), Journal of Advances in Modeling Earth Sys... |
UEARTH-000030 | 30 | Aerosol-Cloud Microphysical Buffering and Radiative Forcing in Mixed-Phase Clouds | How do ice-nucleating particles, secondary ice production (Hallett-Mossop, droplet fragmentation), and Wegener-Bergeron-Findeisen phase partitioning control the liquid-water path and albedo of high-latitude and mid-latitude mixed-phase clouds? | What controls the balance of supercooled liquid water and ice crystals in clouds between 0°C and -38°C, and how does pollution change their brightness? | In supercooled mixed-phase clouds ($235\,\mathrm{K} < T < 273\,\mathrm{K}$), what microphysical rates of heterogeneous immersion freezing, rime splintering, and turbulent updraft supersaturation govern cloud glaciation timescales and cloud-phase radiative feedback? | atmosphere_weather_atmospheric_chemistry | 6 | Atmosphere, Weather, and Atmospheric Chemistry | cloud_microphysics_aerosol_ccn_in | 4 | [
"mechanism",
"budget"
] | [
"troposphere",
"boundary_layer"
] | [
"aerosol_or_cloud_hydrometeor",
"cloud_water"
] | [
"cloud_microphysics_and_aerosol_interaction",
"radiative_transfer_and_energy_balance"
] | regional_synoptic | Global and Representative Regional Observatories | diurnal_to_synoptic | Holocene | [
"aircraft in-situ cloud-droplet/ice-crystal optical array probes and dual-polarization Doppler cloud radar/lidar",
"continuous-flow diffusion chamber ice-nucleating particle (INP) spectra and CCN supersaturation counters"
] | [
"secondary ice production (SIP) multiplication rates and supercooled liquid-to-ice phase partitioning"
] | [
"Köhler droplet activation supersaturation $S(r) = 1 + A/r - \\kappa_{\\mathrm{hyg}} r_{\\mathrm{dry}}^3 / r^3$ and Wegener-Bergeron-Findeisen relaxation $\\tau_{\\mathrm{phase}}^{-1} = 4\\pi D_v (N_w r_w + N_i C_i)$",
"autoconversion-accretion warm-rain balance $\\partial_t q_r = k_{\\mathrm{auto}} q_c^{\\alpha_... | Formulated in Climate Change 2021: The Physical Science Basis (IPCC AR6 WGI) (2021, Chapter 7 Section 7.4); corroborated across Bikkina et al. (2026) and Frostenberg et al. (2026). Remains open due to coupled updraft supersaturation fluctuations, radiative cloud-top cooling, and aerosol loading perturbations and lower-... | Co-located observations of aircraft in-situ cloud-droplet/ice-crystal optical array probes and dual-polarization Doppler cloud radar/lidar and continuous-flow diffusion chamber ice-nucleating particle (INP) spectra and CCN supersaturation counters across Global and Representative Regional Observatories coupled with pro... | open | model_structural_uncertainty | OPEN-VERIFIED | true | hard | 4 | 2,021 | IPCC Working Group I | 2026-10-16T00:00:00 | [
"UEARTH-000205",
"UEARTH-006523",
"UEARTH-007812"
] | [
"10.1017/9781009157896",
"10.1021/acsestair.5c00471",
"10.1038/s41612-026-01342-7",
"10.1029/2019RG000678"
] | [
"Climate Change 2021: The Physical Science Basis (IPCC AR6 WGI) (2021), Clouds and Aerosols (Chapter 7 Section 7.4), DOI:10.1017/9781009157896",
"Bikkina et al. (2026), ACS ES&T Air, DOI:10.1021/acsestair.5c00471",
"Frostenberg et al. (2026), NPJ climate and atmospheric science, DOI:10.1038/s41612-026-01342-7",... |
UEARTH-000031 | 31 | Subtropical Marine Low-Cloud Feedback and the Upper Bound of Equilibrium Climate Sensitivity | How do boundary-layer decoupling, cloud-top radiative cooling, and entrainment drying govern the response of subtropical marine stratocumulus and trade-wind cumulus decks to surface warming, and what sets the upper bound of Equilibrium Climate Sensitivity? | How strongly will low ocean clouds thin as the planet warms, and how much extra warming will that cloud loss cause? | In eastern subtropical ocean basins, what quantitative balance between latent heat flux drying (moisture-gradient entrainment) and cloud-top longwave cooling reduction controls low-cloud optical depth and fractional coverage feedback ($\lambda_{\mathrm{cloud}}$ in $\mathrm{W\,m^{-2}\,K^{-1}}$)? | climate_dynamics_feedbacks_predictability_extremes | 7 | Climate Dynamics, Feedbacks, Predictability, and Extremes | climate_sensitivity_cloud_radiative_feedbacks | 4 | [
"mechanism",
"feedback"
] | [
"atmosphere",
"ocean"
] | [
"tropospheric_air",
"aerosol_or_cloud_hydrometeor"
] | [
"radiative_transfer_and_energy_balance",
"cloud_microphysics_and_aerosol_interaction"
] | planetary_global | Global and Representative Regional Observatories | multidecadal | Anthropocene | [
"CERES/ERBE top-of-atmosphere radiative energy budget time series and Argo global ocean heat uptake",
"A-Train active cloud radar/lidar radiative kernel decompositions and CMIP6 multi-model ensembles"
] | [
"state dependence of tropical anvil-cloud area and extratropical mixed-phase optical-depth feedbacks"
] | [
"radiative feedback decomposition $N(t) = \\Delta F(t) + (\\lambda_P + \\lambda_{\\mathrm{WV+LR}} + \\lambda_{\\mathrm{alb}} + \\lambda_{\\mathrm{cld}} + \\Delta \\lambda_{\\mathrm{pattern}}(t)) \\Delta T_s(t)$",
"Equilibrium Climate Sensitivity $\\mathrm{ECS} = -F_{2\\times\\mathrm{CO2}} / \\lambda_{\\mathrm{net... | Formulated in An Assessment of Earth's Climate Sensitivity Using Multiple Lines of Evidence (2020, Section 3.2); corroborated across McGraw et al. (2025) and Hirota et al. (2021). Remains partially solved due to coupled anthropogenic greenhouse-gas radiative forcing and spatially heterogeneous aerosol forcing and tropi... | Co-located observations of CERES/ERBE top-of-atmosphere radiative energy budget time series and Argo global ocean heat uptake and A-Train active cloud radar/lidar radiative kernel decompositions and CMIP6 multi-model ensembles across Global and Representative Regional Observatories coupled with process-resolving models... | partially_solved | mechanism_known_magnitude_uncertain | PARTIAL-PROGRESS | true | hard | 4 | 2,020 | S. C. Sherwood, M. J. Webb | 2026-10-16T00:00:00 | [
"UEARTH-007982",
"UEARTH-000207",
"UEARTH-006317"
] | [
"10.1029/2019RG000678",
"10.1029/2024gl112368",
"10.1088/1748-9326/abfb9e",
"10.1017/9781009157896"
] | [
"An Assessment of Earth's Climate Sensitivity Using Multiple Lines of Evidence (2020), Cloud Feedbacks (Section 3.2), DOI:10.1029/2019RG000678",
"McGraw et al. (2025), Geophysical Research Letters, DOI:10.1029/2024gl112368",
"Hirota et al. (2021), Environmental Research Letters, DOI:10.1088/1748-9326/abfb9e",
... |
UEARTH-000032 | 32 | Stability Thresholds and Early-Warning Observables for Atlantic Meridional Overturning Circulation (AMOC) | Does the Atlantic Meridional Overturning Circulation (AMOC) possess a salt-advection bistability threshold reachable under 21st-century Greenland meltwater and precipitation forcing, and can freshwater transport diagnostics ($F_{\mathrm{ovS}}$) distinguish approaching criticality from multidecadal internal variability? | Could Atlantic ocean currents cross a tipping point and shut down due to freshwater melting from Greenland, and can ocean measurements warn us in advance? | At $34^\circ\mathrm{S}$ and $26.5^\circ\mathrm{N}$ (RAPID-MOCHA), is the net overturning freshwater import $F_{\mathrm{ov}}$ robustly negative, and how do wind-driven gyre salt transport and Nordic Seas overflow mixing modify the Stommel salt-advection bifurcation boundary? | climate_dynamics_feedbacks_predictability_extremes | 7 | Climate Dynamics, Feedbacks, Predictability, and Extremes | global_carbon_climate_tipping_feedbacks | 4 | [
"mechanism",
"threshold"
] | [
"atmosphere",
"biosphere"
] | [
"tropospheric_air",
"biota"
] | [
"carbon_cycle_and_biogeochemical_cycling",
"radiative_transfer_and_energy_balance"
] | planetary_global | Pan-Arctic Cryosphere, Greenland, and Boreal Permafrost Domain | centennial_to_millennial | Quaternary | [
"global atmospheric CO2/CH4/N2O flask networks, satellite column XCO2/XCH4 (OCO-2/GOSAT), and ocean pCO2",
"coupled C4MIP Earth System Model simulations and paleoclimate abrupt-transition records"
] | [
"critical warming thresholds and cascading interactions among Earth-system tipping elements"
] | [
"Arora carbon-climate feedback framework $\\Delta C_L + \\Delta C_O = (\\beta_L + \\beta_O) \\Delta C_A + (\\gamma_L + \\gamma_O) \\Delta T_s$",
"early-warning critical slowing down autocorrelation $\\mathrm{AR}(1) = \\exp(-\\lambda_{\\mathrm{rest}} \\Delta t) \\to 1$ and variance $\\sigma_x^2 = \\sigma_\\eta^2 /... | Formulated in Exceeding 1.5°C global warming could trigger multiple climate tipping points (2022, Table 1 AMOC); corroborated across Shin et al. (2024) and Sun et al. (2020). Remains open due to coupled cumulative anthropogenic carbon emissions and high-latitude/tropical warming amplification and ocean carbonate buffer... | Co-located observations of global atmospheric CO2/CH4/N2O flask networks, satellite column XCO2/XCH4 (OCO-2/GOSAT), and ocean pCO2 and coupled C4MIP Earth System Model simulations and paleoclimate abrupt-transition records across Pan-Arctic Cryosphere, Greenland, and Boreal Permafrost Domain coupled with process-resolv... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,022 | David I. Armstrong McKay, Arie Staal | 2026-10-16T00:00:00 | [
"UEARTH-009448",
"UEARTH-009177",
"UEARTH-009850"
] | [
"10.1126/science.abn7950",
"10.1029/2024gl108272",
"10.1002/joc.6695",
"10.1017/9781009157896"
] | [
"Exceeding 1.5°C global warming could trigger multiple climate tipping points (2022), Ocean Circulation Tipping Elements (Table 1 AMOC), DOI:10.1126/science.abn7950",
"Shin et al. (2024), Geophysical Research Letters, DOI:10.1029/2024gl108272",
"Sun et al. (2020), International Journal of Climatology, DOI:10.10... |
UEARTH-000033 | 33 | Marine Ice Sheet and Marine Ice Cliff Instability Thresholds in West Antarctica | What basal sliding law, sub-shelf melt distribution, and hydrofracture-driven ice-cliff structural failure criteria govern the rate of grounding-line retreat in retrograde West Antarctic basins such as Thwaites and Pine Island Glaciers? | How fast will West Antarctic glaciers retreat once warm ocean water melts their floating ice shelves, and will towering ice cliffs collapse rapidly? | Along retrograde bedrock slopes in the Amundsen Sea Embayment, does sub-shelf cavity basal melting trigger self-sustaining Marine Ice Sheet Instability (MISI) amplified by Marine Ice Cliff Instability (MICI), or do mélange buttressing and viscoelastic mantle rebound stabilize retreat rates (governed by three-equation s... | cryosphere_permafrost_sea_level | 8 | Cryosphere, Permafrost, and Sea Level | ice_sheet_grounding_line_marine_instability | 5 | [
"mechanism",
"threshold"
] | [
"ice_sheet",
"ice_shelf"
] | [
"ice_or_snow",
"seawater"
] | [
"cryospheric_melt_and_ice_flow",
"ocean_circulation_and_mixing"
] | continental | Antarctica and the Southern Ocean | centennial_to_millennial | Quaternary | [
"ICESat-2/CryoSat-2 laser/radar altimetry, Sentinel-1 InSAR ice-velocity fields, and airborne ice-penetrating radar",
"autonomous underwater vehicle (AUV) sub-ice-shelf cavity hydrography and borehole basal water pressures"
] | [
"irreversible grounding-line retreat thresholds under Marine Ice Sheet and Ice Cliff Instability (MISI/MICI)"
] | [
"Schoof grounding-line flux $q_g = [A (\\rho_i g)^3 (1 - \\rho_i/\\rho_w)^3 / (4^3 C_b)]^{1/(m+1)} h_g^{(m+n+3)/(m+1)}$ with Coulomb-regularized basal sliding $\\tau_b = C u_b^m N (u_b^m / (C_0 N)^m + 1)^{-1/m}$",
"three-equation sub-ice-shelf melt balance $\\rho_i L_f \\dot{m} = \\rho_w c_w u_* \\Gamma_T (T_w - ... | Formulated in The uncertain future of the Antarctic Ice Sheet (2020, Section 2); corroborated across Hillenbrand et al. (2012) and Shean et al. (2019). Remains open due to coupled Circumpolar Deep Water (CDW) intrusion into ice-shelf cavities and surface meltwater hydrofracturing and retrograde subglacial bed topograph... | Co-located observations of ICESat-2/CryoSat-2 laser/radar altimetry, Sentinel-1 InSAR ice-velocity fields, and airborne ice-penetrating radar and autonomous underwater vehicle (AUV) sub-ice-shelf cavity hydrography and borehole basal water pressures across Antarctica and the Southern Ocean coupled with process-resolvin... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,020 | Frank Pattyn, Mathieu Morlighem | 2026-10-16T00:00:00 | [
"UEARTH-009802",
"UEARTH-009814",
"UEARTH-008142"
] | [
"10.1126/science.aaz5487",
"10.1130/g33469.1",
"10.5194/tc-13-2633-2019",
"10.1146/annurev-environ-012220-011847"
] | [
"The uncertain future of the Antarctic Ice Sheet (2020), Ice Sheet Instability (Section 2), DOI:10.1126/science.aaz5487",
"Hillenbrand et al. (2012), Geology, DOI:10.1130/g33469.1",
"Shean et al. (2019), The cryosphere, DOI:10.5194/tc-13-2633-2019",
"E. A. G. Schuur, B. W. Abbott, R. Commane et al. (2022), ... |
UEARTH-000034 | 34 | Abrupt Thermokarst Thaw versus Gradual Active-Layer Deepening in Permafrost Carbon Release | What fraction of 21st-century pan-Arctic permafrost carbon mobilization will occur through abrupt thermokarst lake formation, thaw slumps, and Yedoma ice-wedge collapse rather than gradual top-down active-layer deepening, and what controls the $\mathrm{CH}_4 — \mathrm{CO}_2$ emission ratio? | How much frozen Arctic soil carbon will be released suddenly through collapsing ground and lakes versus slow surface thawing, and how much will emerge as methane? | Across ice-rich Yedoma and peatland permafrost landscapes, how do ground-ice content, microtopographic drainage reorganization, and anoxic methanogenesis versus methanotrophy partition carbon fluxes between $\mathrm{CO}_2$, ebullitive $\mathrm{CH}_4$, and lateral dissolved organic carbon export? | cryosphere_permafrost_sea_level | 8 | Cryosphere, Permafrost, and Sea Level | permafrost_thermokarst_active_layer_carbon | 5 | [
"mechanism",
"budget"
] | [
"permafrost",
"soil"
] | [
"permafrost_or_frozen_ground",
"soil"
] | [
"cryospheric_melt_and_ice_flow",
"carbon_cycle_and_biogeochemical_cycling"
] | regional | Pan-Arctic Cryosphere, Greenland, and Boreal Permafrost Domain | interannual_to_decadal | Holocene | [
"GTN-P borehole temperature arrays, electrical resistivity tomography (ERT), and active-layer probing",
"eddy-covariance/chamber CO2 and CH4 fluxes and radiocarbon (Delta14C) age of respired/dissolved carbon"
] | [
"abrupt thermokarst collapse rates versus gradual top-down active-layer deepening"
] | [
"Stefan phase-change heat conduction $C_{\\mathrm{eff}}(T) \\partial_t T = \\partial_z (k(T) \\partial_z T)$ where $C_{\\mathrm{eff}}(T) = C_v + L_f \\rho_w (\\partial \\theta_u / \\partial T)$",
"anoxic vs. oxic permafrost carbon mineralization $F_C = k_{\\mathrm{ox}}(T) C_{\\mathrm{thaw}}(z \\le z_{\\mathrm{wt}... | Formulated in Permafrost and Climate Change: Carbon Cycle Feedbacks From the Warming Arctic (2022, Issue 2); corroborated across Qin et al. (2025) and Loiko et al. (2026). Remains open due to coupled polar temperature amplification, winter snow-insulation changes, and boreal wildfire disturbance and ground excess-ice c... | Co-located observations of GTN-P borehole temperature arrays, electrical resistivity tomography (ERT), and active-layer probing and eddy-covariance/chamber CO2 and CH4 fluxes and radiocarbon (Delta14C) age of respired/dissolved carbon across Pan-Arctic Cryosphere, Greenland, and Boreal Permafrost Domain coupled with pr... | open | mechanism_known_magnitude_uncertain | OPEN-VERIFIED | true | hard | 4 | 2,022 | Edward A. G. Schuur, Benjamin W. Abbott | 2026-10-16T00:00:00 | [
"UEARTH-010783",
"UEARTH-010165",
"UEARTH-019627"
] | [
"10.1146/annurev-environ-012220-011847",
"10.1073/pnas.2419206122",
"10.1016/j.scitotenv.2026.181532",
"10.1146/annurev-environ-012220-011847"
] | [
"Permafrost and Climate Change: Carbon Cycle Feedbacks From the Warming Arctic (2022), Future Issues (Issue 2), DOI:10.1146/annurev-environ-012220-011847",
"Qin et al. (2025), Proceedings of the National Academy of Sciences, DOI:10.1073/pnas.2419206122",
"Loiko et al. (2026), The Science of the total environmen... |
UEARTH-000035 | 35 | Submesoscale Frontal Instabilities and Interior Diapycnal Mixing in Ocean Heat Uptake | How do submesoscale mixed-layer instabilities ($0.1\text{--}10\,\mathrm{km}$), internal-tide breaking over rough abyssal topography, and Southern Ocean eddy compensation interact to govern the vertical transport and abyssal sequestration of anthropogenic ocean heat? | How do small ocean swirls and breaking underwater waves move heat from the sea surface into the deep ocean? | Across the global pycnocline and abyssal ocean, what are the relative contributions of symmetric/baroclinic submesoscale subduction, near-inertial wave shear, and topographically trapped internal-tide dissipation ($\kappa_\rho$) to closing the global overturning diapycnal buoyancy budget? | physical_oceanography_ocean_circulation | 9 | Physical Oceanography and Ocean Circulation | mesoscale_submesoscale_eddies_fronts | 1 | [
"mechanism",
"transport"
] | [
"open_ocean",
"sea_surface"
] | [
"seawater",
"dissolved_phase"
] | [
"ocean_circulation_and_mixing",
"radiative_transfer_and_energy_balance"
] | ocean_basin_or_gyre | Antarctica and the Southern Ocean | synoptic_to_seasonal | Anthropocene | [
"SWOT wide-swath interferometer sea-surface height, surface drifter dispersion arrays, and glider high-resolution sections",
"shipboard ADCP velocity shear profiles and eddy-resolving (1/12° to 1/48°) ocean general circulation models"
] | [
"scale-aware eddy diffusivity/backscatter parameterizations and western-boundary-current separation mechanics"
] | [
"quasi-geostrophic potential vorticity conservation $D_g q_{\\mathrm{QG}}/Dt = 0$ where $q_{\\mathrm{QG}} = \\nabla_h^2 \\psi + f + \\partial_z [(f_0^2 / N^2) \\partial_z \\psi]$",
"submesoscale Ertel potential vorticity $q = (f \\hat{\\mathbf{z}} + \\nabla \\times \\mathbf{u}) \\cdot \\nabla b \\le 0$ criterion ... | Formulated in Forecasting the Ocean: The 2025-2035 Decade of Ocean Science (2025, Chapter 2 Question 1); corroborated across Zhang et al. (2023) and Brearley et al. (2013). Remains open due to coupled wind-stress curl, surface buoyancy loss, and lateral density gradients across ocean fronts and continental slope topogr... | Co-located observations of SWOT wide-swath interferometer sea-surface height, surface drifter dispersion arrays, and glider high-resolution sections and shipboard ADCP velocity shear profiles and eddy-resolving (1/12° to 1/48°) ocean general circulation models across Antarctica and the Southern Ocean coupled with proce... | open | mechanism_known_magnitude_uncertain | OPEN-VERIFIED | true | hard | 4 | 2,025 | Committee on the 2025-2035 Decadal Survey of Ocean Sciences | 2026-10-16T00:00:00 | [
"UEARTH-010864",
"UEARTH-011190",
"UEARTH-000220"
] | [
"10.17226/27846",
"10.1038/s41467-023-36991-2",
"10.1175/jpo-d-12-0222.1",
"10.17226/27846"
] | [
"Forecasting the Ocean: The 2025-2035 Decade of Ocean Science (2025), Ocean and Climate (Chapter 2 Question 1), DOI:10.17226/27846",
"Zhang et al. (2023), Nature Communications, DOI:10.1038/s41467-023-36991-2",
"Brearley et al. (2013), Journal of Physical Oceanography, DOI:10.1175/jpo-d-12-0222.1",
"NASEM (20... |
UEARTH-000036 | 36 | Organic Ligand Stabilization and Hydrothermal Export in the Global Marine Iron Cycle | What molecular structures and biogeochemical sources control strong iron-binding organic ligands ($L_1$, $L_2$) in seawater, and how do they allow hydrothermal and margin-derived dissolved iron to escape near-field scavenging and fertilize remote high-nutrient low-chlorophyll surface waters? | How do natural organic molecules bind dissolved iron from deep-sea hydrothermal vents and carry it thousands of kilometers to feed ocean plankton? | Along mid-ocean ridge plumes and continental shelves mapped by GEOTRACES, what kinetic balance among colloidal iron oxyhydroxide aggregation, siderophore/humic ligand complexation, and particle reversible scavenging sets the residence time of dissolved iron ($\mathrm{dFe}$)? | marine_biogeochemistry_seafloor_ocean_ecosystem | 10 | Marine Biogeochemistry, Seafloor, and Ocean-Ecosystem Coupling | geotraces_trace_metals_hydrothermal_vents | 6 | [
"mechanism",
"transport"
] | [
"hydrothermal_system",
"deep_ocean"
] | [
"seawater",
"hydrothermal_fluid"
] | [
"carbon_cycle_and_biogeochemical_cycling",
"redox_transformation"
] | ocean_basin_or_gyre | Global and Representative Regional Observatories | interannual_to_decadal | Holocene | [
"GEOTRACES trace-metal-clean full-depth transects (dFe, dZn, dCo, dMn, dCu) and competitive ligand voltammetry",
"3He/4He plume tracers, ROV hydrothermal fluid samplers, and iron/zinc/cadmium stable isotope profiles"
] | [
"organic ligand complexation and colloidal Nanoparticle stabilization enabling thousand-kilometer hydrothermal iron transport"
] | [
"organic-ligand iron complexation $\\mathrm{Fe}' + L_i \\rightleftharpoons \\mathrm{Fe}L_i$ with conditional stability constant $K_{\\mathrm{Fe}L_i, \\mathrm{Fe}'}^{\\mathrm{cond}} = [\\mathrm{Fe}L_i] / ([\\mathrm{Fe}'][L_i']) \\sim 10^{11}\\text{--}10^{13}\\,\\mathrm{M}^{-1}$",
"reversible particle scavenging ba... | Formulated in The integral role of iron in ocean biogeochemistry (2017, Section 3); corroborated across Fox et al. (2018) and Walker et al. (2016). Remains open due to coupled seafloor hydrothermal venting, mineral dust deposition, and nepheloid-layer sediment resuspension and siderophore binding-ligand concentrations,... | Co-located observations of GEOTRACES trace-metal-clean full-depth transects (dFe, dZn, dCo, dMn, dCu) and competitive ligand voltammetry and 3He/4He plume tracers, ROV hydrothermal fluid samplers, and iron/zinc/cadmium stable isotope profiles across Global and Representative Regional Observatories coupled with process-... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | medium | 3 | 2,017 | Alessandro Tagliabue, Laurent Bopp | 2026-10-16T00:00:00 | [
"UEARTH-012209",
"UEARTH-012340",
"UEARTH-004240"
] | [
"10.1038/nature21058",
"10.3389/fmars.2018.00172",
"10.1002/2016gl070359",
"10.1126/science.aam7240"
] | [
"The integral role of iron in ocean biogeochemistry (2017), Iron Residence Time and Scavenging (Section 3), DOI:10.1038/nature21058",
"Fox et al. (2018), Frontiers in Marine Science, DOI:10.3389/fmars.2018.00172",
"Walker et al. (2016), Geophysical Research Letters, DOI:10.1002/2016gl070359",
"D. Breitburg, L... |
UEARTH-000037 | 37 | Physical Ventilation versus Biogeochemical Respiration Drivers of Tropical Oxygen Minimum Zone Expansion | What are the relative roles of sluggish equatorial zonal jets, changes in wind-driven subduction ventilation, and warming-accelerated microbial remineralization in driving the expansion and shoaling of tropical marine Oxygen Minimum Zones (OMZs)? | Why are low-oxygen dead zones in the tropical oceans expanding—because ocean currents are bringing less fresh oxygen, or because microbes are consuming more? | In the Eastern Tropical Pacific, Atlantic, and Arabian Sea at $100\text{--}800\,\mathrm{m}$ depth, how do eddy-driven lateral isopycnal oxygen supply, temperature-dependent particle attenuation length ($b$-value), and anaerobic fixed-nitrogen loss (anammox/denitrification) govern suboxic volume trajectories? | marine_biogeochemistry_seafloor_ocean_ecosystem | 10 | Marine Biogeochemistry, Seafloor, and Ocean-Ecosystem Coupling | ocean_deoxygenation_omz_nitrogen_cycle | 6 | [
"mechanism"
] | [
"open_ocean",
"continental_shelf"
] | [
"seawater",
"dissolved_phase"
] | [
"redox_transformation",
"carbon_cycle_and_biogeochemical_cycling"
] | ocean_basin_or_gyre | Indian Ocean Basin and South Asian Monsoon System | interannual_to_decadal | Anthropocene | [
"GO-SHIP and BGC-Argo dissolved oxygen optode profiles, 15N-labeled incubation rates, and dual-isotope delta-15N/delta-18O nitrate",
"in-situ nanomolar oxygen sensors (STOX) and dissolved N2/Ar and N2O saturation transects"
] | [
"nanomolar oxygen thresholds triggering fixed-nitrogen loss via heterotrophic denitrification vs. anammox"
] | [
"interior oxygen balance $\\partial_t [\\mathrm{O}_2] + \\mathbf{u} \\cdot \\nabla [\\mathrm{O}_2] - \\nabla \\cdot (\\mathbf{K} \\nabla [\\mathrm{O}_2]) = -r_{\\mathrm{O2:C}} R_{\\mathrm{org}}(z, T)$ with apparent oxygen utilization $\\mathrm{AOU} = [\\mathrm{O}_2]_{\\mathrm{sat}}(T, S) - [\\mathrm{O}_2]$",
"sub... | Formulated in Declining oxygen in the global ocean and coastal waters (2018, Section 2); corroborated across Piscoya et al. (2022) and Zhang et al. (2026). Remains open due to coupled thermocline ventilation slowdown, coastal eutrophication, and organic-matter export pulses and equatorial zonal jet supply of oxygen, be... | Co-located observations of GO-SHIP and BGC-Argo dissolved oxygen optode profiles, 15N-labeled incubation rates, and dual-isotope delta-15N/delta-18O nitrate and in-situ nanomolar oxygen sensors (STOX) and dissolved N2/Ar and N2O saturation transects across Indian Ocean Basin and South Asian Monsoon System coupled with ... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,018 | Denise Breitburg, Lisa A. Levin | 2026-10-16T00:00:00 | [
"UEARTH-012118",
"UEARTH-013072",
"UEARTH-000112"
] | [
"10.1126/science.aam7240",
"10.1016/j.marenvres.2022.105710",
"10.1109/jstars.2026.3690886",
"10.1126/science.aam7240"
] | [
"Declining oxygen in the global ocean and coastal waters (2018), Open Ocean Deoxygenation (Section 2), DOI:10.1126/science.aam7240",
"Piscoya et al. (2022), Marine environmental research, DOI:10.1016/j.marenvres.2022.105710",
"Zhang et al. (2026), IEEE Journal of Selected Topics in Applied Earth Observations an... |
UEARTH-000038 | 38 | Coupled Tectonic Stress, Frost Cracking, and Biogeochemical Controls on Deep Weathering Fronts | What relative roles do topographic tectonic stress, bedrock fracture density, deep microbial/root $\mathrm{CO}_2$ respiration, and frost cracking play in setting the depth and propagation rate of the unweathered bedrock-to-saprolite weathering front? | What controls how deeply solid bedrock breaks down into weathered rock and soil beneath hills and valleys? | From ridge crests to valley bottoms across lithological and climatic gradients, does the depth of the chemical weathering front (acid-base and redox reaction fronts) track the seasonal water-table fluctuation zone, topographic compressive stress trajectories, or mineral dissolution kinetics (governed by 1D reactive tra... | soils_critical_zone_terrestrial_biogeochemistry | 12 | Soils, Critical Zone, and Terrestrial Biogeochemistry | critical_zone_weathering_regolith_architecture | 7 | [
"mechanism",
"feedback"
] | [
"critical_zone",
"regolith"
] | [
"crystalline_rock",
"pore_water"
] | [
"chemical_weathering",
"groundwater_flow_and_transport"
] | hillslope_to_catchment | Global and Representative Regional Observatories | millennial_to_orbital | Quaternary | [
"deep Critical Zone borehole cores, seismic refraction/resistivity tomography, and mass-transfer tau (τ) profiles",
"high-frequency stream concentration-discharge (C-Q) chemostatic slopes and Li/Mg/Si/U-series weathering isotopes"
] | [
"topographic stress, frost cracking, and deep oxidative/acid reactions controlling the depth of the bedrock weathering front"
] | [
"1D reactive transport weathering front propagation $w_{\\mathrm{front}} = q_{\\mathrm{infil}} (C_{\\mathrm{eq}} - C_0) / (\\rho_b m_{\\mathrm{min}})$ and Maher Damköhler number $\\mathrm{Da}_{\\mathrm{weath}} = k_{\\mathrm{eff}} A_s L / q_{\\mathrm{infil}}$",
"chemical depletion fraction $\\mathrm{CDF} = 1 - [\\... | Formulated in Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth (2017, Question 1); corroborated across Shen et al. (2026) and Osorio‐Leon et al. (2025). Remains open due to coupled meteoric water infiltration, biogenic soil CO2/organic-acid production, and tectonic ... | Co-located observations of deep Critical Zone borehole cores, seismic refraction/resistivity tomography, and mass-transfer tau (τ) profiles and high-frequency stream concentration-discharge (C-Q) chemostatic slopes and Li/Mg/Si/U-series weathering isotopes across Global and Representative Regional Observatories coupled... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | medium | 3 | 2,017 | S. L. Brantley, W. H. McDowell | 2026-10-16T00:00:00 | [
"UEARTH-015895",
"UEARTH-000253",
"UEARTH-002656"
] | [
"10.5194/esurf-5-841-2017",
"10.1186/s12870-026-08252-z",
"10.1029/2025av001692",
"10.5194/esurf-5-841-2017"
] | [
"Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth (2017), Common Critical Zone Questions (Question 1), DOI:10.5194/esurf-5-841-2017",
"Shen et al. (2026), BMC Plant Biology, DOI:10.1186/s12870-026-08252-z",
"Osorio‐Leon et al. (2025), AGU Advances, DOI:10.10... |
UEARTH-000039 | 39 | Mineral-Associated versus Particulate Soil Organic Carbon Vulnerability to Warming | Under sustained soil warming and rhizosphere priming, what organo-mineral sorption, iron-oxide redox dissolution, and microbial carbon-use efficiency mechanisms control the destabilization of millennia-old mineral-associated organic matter (MAOM)? | Can soil warming and plant root activity unlock ancient carbon that was thought to be safely bound to clay and iron minerals? | Across mineral soil horizons ($0\text{--}2\,\mathrm{m}$ depth), how do root exudate organic acids (oxalate, citrate), fluctuating redox mobilization of short-range-ordered Fe/Al phases, and temperature sensitivity of microbial exoenzymes govern the turnover time of mineral-associated versus particulate organic carbon p... | soils_critical_zone_terrestrial_biogeochemistry | 12 | Soils, Critical Zone, and Terrestrial Biogeochemistry | soil_organic_carbon_mineral_stabilization_priming | 7 | [
"mechanism"
] | [
"soil",
"critical_zone"
] | [
"soil",
"biota"
] | [
"carbon_cycle_and_biogeochemical_cycling",
"chemical_weathering"
] | molecular_to_pore | Global and Representative Regional Observatories | decadal | Anthropocene | [
"density/size fractionation (MAOM vs. POM), 13C/14C isotopic pulse-labeling, and solid-state 13C NMR / NanoSIMS",
"long-term soil warming manipulation plots and automated chamber heterotrophic respiration fluxes"
] | [
"thermal adaptation of microbial carbon-use efficiency (CUE) and root-exudate priming of ancient subsoil carbon"
] | [
"microbial-mineral soil carbon dynamics $dC_{\\mathrm{MAOM}}/dt = f_{\\mathrm{MAOM}} \\cdot \\mathrm{CUE}(T) V_{\\max}(T) \\frac{C_{\\mathrm{DOC}} B_{\\mathrm{mic}}}{K_m + C_{\\mathrm{DOC}}} (1 - \\frac{C_{\\mathrm{MAOM}}}{C_{\\max}}) - k_{\\mathrm{des}}(T, [\\mathrm{oxalate}]) C_{\\mathrm{MAOM}}$",
"temperature ... | Formulated in The contentious nature of soil organic matter (2015, Section 4); corroborated across Zhu et al. (2026) and Xie et al. (2025). Remains open due to coupled soil warming, labile root-exudate inputs, and drying-rewetting Birch-effect cycles and reactive short-range-order Fe/Al oxyhydroxide content, clay miner... | Co-located observations of density/size fractionation (MAOM vs. POM), 13C/14C isotopic pulse-labeling, and solid-state 13C NMR / NanoSIMS and long-term soil warming manipulation plots and automated chamber heterotrophic respiration fluxes across Global and Representative Regional Observatories coupled with process-reso... | open | active_debate | OPEN-VERIFIED | true | medium | 3 | 2,015 | Johannes Lehmann, Markus Kleber | 2026-10-16T00:00:00 | [
"UEARTH-000243",
"UEARTH-014883",
"UEARTH-002711"
] | [
"10.1038/nature16069",
"10.1111/1365-2664.70364",
"10.1021/acs.est.5c03041",
"10.5194/esurf-5-841-2017"
] | [
"The contentious nature of soil organic matter (2015), Soil Continuum Model (Section 4), DOI:10.1038/nature16069",
"Zhu et al. (2026), Journal of Applied Ecology, DOI:10.1111/1365-2664.70364",
"Xie et al. (2025), Environmental Science & Technology, DOI:10.1021/acs.est.5c03041",
"S. L. Brantley, W. H. McDowell... |
UEARTH-000040 | 40 | Post-Fire Biome Tipping Thresholds and Carbon-Albedo Feedbacks in Boreal and Tropical Forests | Under what combinations of shortened fire return intervals, post-fire megadrought, and soil mycorrhizal loss do burned boreal and tropical forests fail to regenerate and transition irreversibly into non-forest or savanna states, and what is the net radiative feedback? | When do repeated wildfires and droughts permanently turn forests into grasslands or shrublands, and does that shift warm or cool the climate? | In boreal conifer forests and humid tropical forests, how does the competition between positive carbon-release radiative forcing ($\Delta \mathrm{CO}_2$, black carbon deposition on snow) and negative surface-albedo change after fire-driven state shifts determine net regional and global radiative forcing? | ecosystem_earth_interactions_land_change | 13 | Ecosystem-Earth Interactions, Land Change, and Environmental Response | wildfire_regimes_pyrogenic_carbon_recovery | 9 | [
"mechanism",
"threshold"
] | [
"forest",
"grassland"
] | [
"biota",
"tropospheric_air"
] | [
"ecosystem_disturbance_and_biophysical_feedback",
"carbon_cycle_and_biogeochemical_cycling"
] | regional | Pan-Arctic Cryosphere, Greenland, and Boreal Permafrost Domain | interannual_to_decadal | Holocene | [
"MODIS/VIIRS active-fire radiative power, Landsat/Sentinel-2 burn-severity (dNBR) maps, and tree-ring fire scars",
"benzene polycarboxylic acid (BPCA) pyrogenic carbon markers and post-fire chronosequence regeneration surveys"
] | [
"climate-driven vs. fuel-limitation switches in global burned area and boreal-to-deciduous post-fire state shifts"
] | [
"Rothermel-Byram fireline intensity $I_B = H_c w_{\\mathrm{fuel}} R_{\\mathrm{spread}}(U, \\theta_{\\mathrm{slope}}, m_f(\\mathrm{VPD}))$",
"net post-fire radiative forcing $\\Delta F_{\\mathrm{net}}(t) = \\Delta F_{\\mathrm{GHG}}(E_{\\mathrm{CO2,CH4,N2O}}) + \\Delta F_{\\mathrm{aer}} + \\Delta R_{\\mathrm{SW}}(\... | Formulated in Vegetation fires in the Anthropocene (2020, Section 5); corroborated across Werner et al. (2024) and Dou et al. (2025). Remains open due to coupled fire-weather indices (VPD, wind), dry lightning ignition, and human fire suppression/fragmentation and live/dead fuel moisture connectivity, bark thickness/se... | Co-located observations of MODIS/VIIRS active-fire radiative power, Landsat/Sentinel-2 burn-severity (dNBR) maps, and tree-ring fire scars and benzene polycarboxylic acid (BPCA) pyrogenic carbon markers and post-fire chronosequence regeneration surveys across Pan-Arctic Cryosphere, Greenland, and Boreal Permafrost Doma... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | medium | 3 | 2,020 | David M. J. S. Bowman, Crystal A. Kolden | 2026-10-16T00:00:00 | [
"UEARTH-000247",
"UEARTH-017515",
"UEARTH-007892"
] | [
"10.1038/s43017-020-0085-3",
"10.1002/ecs2.70119",
"10.1016/j.geoderma.2025.117237",
"10.1038/s43017-020-0085-3"
] | [
"Vegetation fires in the Anthropocene (2020), Fire Regime Shifts (Section 5), DOI:10.1038/s43017-020-0085-3",
"Werner et al. (2024), Ecosphere, DOI:10.1002/ecs2.70119",
"Dou et al. (2025), Geoderma, DOI:10.1016/j.geoderma.2025.117237",
"D. M. J. S. Bowman, C. A. Kolden, J. T. Abatzoglou et al. (2020), Vegetat... |
UEARTH-000041 | 41 | Vadose-Zone Air-Water Interfacial Retention and Precursor Biotransformation of PFAS | What coupled air-water interfacial adsorption, surfactant micellization, and polyfluorinated precursor biotransformation rates govern the multi-decadal retention and mass discharge of per- and polyfluoroalkyl substances (PFAS) from unsaturated soils to groundwater? | What traps 'forever chemicals' (PFAS) at air-water boundaries in unsaturated soil and controls how fast precursor compounds break down and leach into groundwater? | In unsaturated vadose zones, how do dynamic water-table fluctuations, soil organic carbon content, ionic strength, and aerobic/anaerobic microbial defluorination or oxidation of fluorotelomer precursors control the long-term tailing of perfluoroalkyl acids (PFAAs) into underlying aquifers (governed by sequential precur... | pollution_contaminant_fate_environmental_quality | 14 | Pollution, Contaminant Fate, and Environmental Quality | pfas_forever_chemicals_transport_fate | 9 | [
"mechanism",
"predictability"
] | [
"vadose_zone",
"groundwater"
] | [
"groundwater",
"pore_water"
] | [
"contaminant_transport_and_fate",
"groundwater_flow_and_transport"
] | river_basin_or_aquifer | Global and Representative Regional Observatories | decadal | Anthropocene | [
"LC-HRMS suspect/non-target screening, extractable organic fluorine (EOF) mass balance, and total oxidizable precursor (TOP) assays",
"unsaturated-zone lysimeter profiles and air-water interface adsorption surface-tension isotherms"
] | [
"biotransformation pathways of polyfluorinated precursors into terminal perfluoroalkyl acids and sea-spray atmospheric cycling"
] | [
"air-water interfacial vadose retardation $R_f = 1 + (\\rho_b K_d(\\mathrm{f_{oc}}))/\\theta_w + (K_{ai}(C, I) A_{ai}(\\theta_w))/\\theta_w$ where $K_{ai} = -(R T)^{-1} (\\partial \\gamma_{\\mathrm{aw}} / \\partial C)$",
"sequential precursor biotransformation $\\partial_t C_k + R_{f,k}^{-1} \\mathbf{v} \\cdot \\... | Formulated in Per- and polyfluoroalkyl substances in the environment (2022, Section 3); corroborated across Lemay et al. (2025) and Yan et al. (2026). Remains open due to coupled infiltration wetting-front velocity, ionic strength fluctuations, and co-contaminant NAPL/surfactant presence and vadose-zone air-water inter... | Co-located observations of LC-HRMS suspect/non-target screening, extractable organic fluorine (EOF) mass balance, and total oxidizable precursor (TOP) assays and unsaturated-zone lysimeter profiles and air-water interface adsorption surface-tension isotherms across Global and Representative Regional Observatories coupl... | open | mechanism_known_magnitude_uncertain | OPEN-VERIFIED | true | medium | 3 | 2,022 | Marina G. Evich, Mary J. B. Davis | 2026-10-16T00:00:00 | [
"UEARTH-000299",
"UEARTH-017707",
"UEARTH-013417"
] | [
"10.1126/science.abg9065",
"10.1021/acs.est.4c08285",
"10.1021/acs.est.6c06855",
"10.1126/science.abg9065"
] | [
"Per- and polyfluoroalkyl substances in the environment (2022), Environmental Fate and Transport (Section 3), DOI:10.1126/science.abg9065",
"Lemay et al. (2025), Environmental Science & Technology, DOI:10.1021/acs.est.4c08285",
"Yan et al. (2026), Environmental Science & Technology, DOI:10.1021/acs.est.6c06855"... |
UEARTH-000042 | 42 | Relative Contributions of Aquifer Compaction, Sediment Starvation, and Isostasy to Delta Subsidence | Across major populated river deltas, what are the relative quantitative contributions of shallow Holocene peat/clay autocompaction, deep groundwater/hydrocarbon extraction, and upstream dam sediment starvation to net relative sea-level rise and deltaic drowning? | How much of the sinking of major river deltas is caused by groundwater pumping and upstream dams versus natural compaction of young mud and peat? | In megadeltas (Ganges-Brahmaputra, Mekong, Mississippi, Nile, Yangtze), how can depth-resolved extensometry, InSAR persistent scatterers, and stratigraphic compaction modeling partition shallow ($<30\,\mathrm{m}$) organic/clay consolidation from deep poroelastic/inelastic aquifer-system compaction? | coasts_deltas_drylands_urban_coupled_systems | 15 | Coasts, Deltas, Drylands, Urban Environments, and Coupled Human-Earth Systems | river_deltas_avulsion_subsidence_salinity | 9 | [
"mechanism"
] | [
"delta",
"estuary"
] | [
"fluvial_or_coastal_sediment",
"seawater"
] | [
"coastal_and_estuarine_morphodynamics",
"sediment_transport_and_deposition"
] | sedimentary_basin_or_continental_margin | North American Cordilleran, Cratonic, and Coastal Margin Systems | interannual_to_decadal | Holocene | [
"multi-temporal InSAR surface displacement velocity fields and continuous GNSS station networks",
"InSAR + rod-extensometer vertical compaction rates, ADCP/CTD estuarine salt-flux transects, and 222Rn/226Ra SGD tracers"
] | [
"partitioning of deltaic relative sea-level rise between shallow Holocene mud compaction, deep tectonic subsidence, and groundwater/hydrocarbon extraction"
] | [
"relative sea-level rise and delta subsidence $\\mathrm{RSLR}_{\\mathrm{net}} = \\dot{\\eta}_{\\mathrm{eustatic}} + S_{\\mathrm{GIA}} + \\int_0^Z m_v(z) \\partial_t P_{\\mathrm{pore}}(z) dz + S_{\\mathrm{creep}} - \\dot{\\eta}_{\\mathrm{aggrad}}$",
"estuarine MacCready salt-intrusion length $L_s \\propto H^3 N_0^... | Formulated in Earth's sediment cycle during the Anthropocene (2022, Section 5); corroborated across Liu et al. (2021) and Feng et al. (2022). Remains open due to coupled upstream reservoir sediment starvation, channel dredging, groundwater pumping, and sea-level rise and distributary bifurcation geometry, Holocene peat... | Co-located observations of multi-temporal InSAR surface displacement velocity fields and continuous GNSS station networks and InSAR + rod-extensometer vertical compaction rates, ADCP/CTD estuarine salt-flux transects, and 222Rn/226Ra SGD tracers across North American Cordilleran, Cratonic, and Coastal Margin Systems co... | open | regional_resolution_only | OPEN-VERIFIED | true | medium | 3 | 2,022 | Jaia Syvitski, Juan Restrepo Ángel | 2026-10-16T00:00:00 | [
"UEARTH-019031",
"UEARTH-019055",
"UEARTH-005033"
] | [
"10.1038/s43017-021-00253-w",
"10.1016/j.scitotenv.2020.142165",
"10.3389/fpls.2022.946129",
"10.1038/s41558-021-00993-z"
] | [
"Earth's sediment cycle during the Anthropocene (2022), Deltaic Sinks (Section 5), DOI:10.1038/s43017-021-00253-w",
"Liu et al. (2021), The Science of the total environment, DOI:10.1016/j.scitotenv.2020.142165",
"Feng et al. (2022), Frontiers in plant science, DOI:10.3389/fpls.2022.946129",
"R. J. Nicholls, D... |
UEARTH-000043 | 43 | Innovative Measurement Technologies for Subsurface Hydrological States and Fluxes (UPH 16) | How can hydrogeophysics, distributed fiber-optic sensing, and cosmic-ray neutron probes be combined to measure three-dimensional subsurface water storage and fluxes at hillslope-to-catchment scales? | How can new sensing technologies map underground water storage and movement across entire hillsides and watersheds? | What multi-physics inversion frameworks can link electrical resistivity, seismic velocity, cosmic-ray neutron moderation, and distributed temperature sensing to direct volumetric soil-moisture and groundwater flux fields without site-specific empirical calibration (governed by master transit-time StorAge Selection (SAS... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | catchment_runoff_transit_time_uph | 2 | [
"mechanism"
] | [
"river",
"vadose_zone"
] | [
"freshwater_surface",
"pore_water"
] | [
"hydrological_partitioning_and_runoff",
"groundwater_flow_and_transport"
] | hillslope_to_catchment | Global and Representative Regional Observatories | synoptic_to_seasonal | Anthropocene | [
"deep magnetotelluric (MT) and electrical resistivity tomography (ERT) conductivity inversions",
"high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge"
] | [
"emergent catchment-scale storage-discharge constitutive relations from heterogeneous hillslope preferential flow"
] | [
"Kirchner dynamical catchment storage-discharge sensitivity $g(Q) = dQ/dS = (-dQ/dt) / (Q - P + E)$ and power-law recession $-dQ/dt = a Q^b$",
"master transit-time StorAge Selection (SAS) transport $\\partial_t S_T(T, t) + \\partial_T S_T(T, t) = J(t) - Q(t) \\Omega_Q(S_T, t) - E(t) \\Omega_E(S_T, t)$"
] | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 16); corroborated across Baroni et al. (2017) and Schmied et al. (2014). Remains open due to coupled convective vs. stratiform storm hyetographs, antecedent soil moisture, and seasonal potential evapotranspiration and b... | Co-located observations of deep magnetotelluric (MT) and electrical resistivity tomography (ERT) conductivity inversions and high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge across Global and Representative Regional Observatories coupled with pr... | open | framework_dependent | OPEN-VERIFIED | true | medium | 3 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-013452",
"UEARTH-013662",
"UEARTH-005073"
] | [
"10.1080/02626667.2019.1620507",
"10.5194/hess-21-2301-2017",
"10.5194/hess-18-3511-2014",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Measurements and Data (UPH 16), DOI:10.1080/02626667.2019.1620507",
"Baroni et al. (2017), Hydrology and earth system sciences, DOI:10.5194/hess-21-2301-2017",
"Schmied et al. (2014), Hydrology and earth system sciences, DOI:10... |
UEARTH-000044 | 44 | Information Content of Traditional Hydrological Observations Versus Novel Proxies (UPH 17) | What is the relative information content of long-term point stream-gauge records versus spatially distributed satellite and citizen-science observations for constraining hydrological process models? | How much new physical insight do satellite images and unconventional water observations add compared to traditional river gauges? | In an information-theoretic diagnostic framework, how do temporal resolution, spatial support volume, and measurement error structure trade off when assimilating SWOT-type surface-water altimetry, GRACE gravimetry, and stage-discharge records (governed by hyporheic Damköhler number $\mathrm{Da} = \tau_{\mathrm{res}} k_... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | hyporheic_river_groundwater_lake_wetland | 2 | [
"mechanism"
] | [
"river",
"wetland"
] | [
"freshwater_surface",
"pore_water"
] | [
"groundwater_flow_and_transport",
"hydrological_partitioning_and_runoff"
] | reach | Global and Representative Regional Observatories | synoptic_to_seasonal | Holocene | [
"GRACE/GRACE-FO satellite gravimetry terrestrial water storage and ice-mass anomaly fields",
"fiber-optic distributed temperature sensing (FO-DTS), 222Rn/He exchange tracers, and streambed vertical head gradients"
] | [
"multi-scale hyporheic exchange residence-time distributions driven by bedforms, bars, and meandering"
] | [
"hyporheic Damköhler number $\\mathrm{Da} = \\tau_{\\mathrm{res}} k_{\\mathrm{rxn}}$ governing aerobic-to-denitrifying redox transition along bedform streamlines",
"1D Saint-Venant transient channel-storage routing $\\partial_t A + \\partial_x Q = q_{\\mathrm{lat}} - q_{\\mathrm{hyp}}(A_s / A) \\partial_t (C_s - ... | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 17); corroborated across Shrestha et al. (2025) and Chen et al. (2026). Remains open due to coupled stage fluctuations, bedform-induced hydrostatic/hydrodynamic pressure gradients, and seasonal water-table shifts and st... | Co-located observations of GRACE/GRACE-FO satellite gravimetry terrestrial water storage and ice-mass anomaly fields and fiber-optic distributed temperature sensing (FO-DTS), 222Rn/He exchange tracers, and streambed vertical head gradients across Global and Representative Regional Observatories coupled with process-res... | open | framework_dependent | OPEN-VERIFIED | true | medium | 3 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-013652",
"UEARTH-013892",
"UEARTH-000122"
] | [
"10.1080/02626667.2019.1620507",
"10.1029/2024wr038183",
"10.3390/hydrology13070172",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Measurements and Data (UPH 17), DOI:10.1080/02626667.2019.1620507",
"Shrestha et al. (2025), Water Resources Research, DOI:10.1029/2024wr038183",
"Chen et al. (2026), Hydrology, DOI:10.3390/hydrology13070172",
"B. Arheimer, C... |
UEARTH-000045 | 45 | Human-Water Feedbacks and Emergent Dynamics in Socio-Hydrological Systems (UPH 18) | How do endogenous feedbacks between human water abstraction, reservoir regulation, flood-risk memory, and hydrological extremes generate emergent phenomena such as the levee effect and supply-demand pendulums? | How do human decisions about dams, levees, and groundwater pumping feed back on river flows, floods, and droughts over decades? | In coupled human-water catchments, what nonlinear dynamical feedbacks link flood memory decay, floodplain urbanization, irrigation efficiency rebound (Jevons paradox), and aquifer depletion to multi-decadal hydrological regime shifts (governed by runoff-precipitation elasticity $\varepsilon_Q = (\bar{P}/\bar{Q}) (dQ/dP... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | hydroclimatic_extremes_floods_drought_propagation | 2 | [
"mechanism"
] | [
"hydrosphere_freshwater",
"river"
] | [
"freshwater_surface",
"groundwater"
] | [
"hydrological_partitioning_and_runoff",
"groundwater_flow_and_transport"
] | river_basin_or_aquifer | Global and Representative Regional Observatories | interannual_to_decadal | Anthropocene | [
"multi-decade stream-gauge networks, standardized precipitation/runoff/groundwater drought indices, and satellite altimetry",
"coupled land-surface/hydrodynamic routing models and remotely sensed irrigation/reservoir storage records"
] | [
"antagonistic vs. compounding feedbacks between human water-management adaptations and extreme flood/drought risk"
] | [
"Generalized Extreme Value (GEV) non-stationary return level $G(x; \\mu(t), \\sigma(t), \\xi) = \\exp\\{-[1 + \\xi ((x - \\mu(t))/\\sigma(t))]^{-1/\\xi}\\}$",
"runoff-precipitation elasticity $\\varepsilon_Q = (\\bar{P}/\\bar{Q}) (dQ/dP)$ shifting across multi-year drought states"
] | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 18); corroborated across Schmied et al. (2014) and Fan et al. (2026). Remains open due to coupled persistent precipitation deficits, extreme atmospheric-river or monsoon rainfall, and human abstraction/impoundment and b... | Co-located observations of multi-decade stream-gauge networks, standardized precipitation/runoff/groundwater drought indices, and satellite altimetry and coupled land-surface/hydrodynamic routing models and remotely sensed irrigation/reservoir storage records across Global and Representative Regional Observatories coup... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | medium | 3 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-014467",
"UEARTH-014118",
"UEARTH-005091"
] | [
"10.1080/02626667.2019.1620507",
"10.5194/hess-18-3511-2014",
"10.1093/pnasnexus/pgag151",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Interfaces with Society (UPH 18), DOI:10.1080/02626667.2019.1620507",
"Schmied et al. (2014), Hydrology and earth system sciences, DOI:10.5194/hess-18-3511-2014",
"Fan et al. (2026), PNAS nexus, DOI:10.1093/pnasnexus/pgag151",
... |
UEARTH-000046 | 46 | Hydrological Model Adaptability Under Extrapolated Future Climate and Land-Use Boundary Conditions (UPH 19) | How can hydrological models be structurally formulated so their state-flux parameterizations remain physically valid when extrapolated to unprecedented climate, $\mathrm{CO}_2$, and land-use regimes? | How can we build watershed models that still work accurately when climate and vegetation shift outside anything seen in historical records? | When atmospheric $\mathrm{CO}_2$, vapor pressure deficit, and disturbance regimes shift beyond calibration envelopes, which time-varying ecosystem and subsurface parameters must evolve endogenously to prevent systematic bias in runoff projections? | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | catchment_runoff_transit_time_uph | 2 | [
"mechanism",
"budget"
] | [
"river",
"vadose_zone"
] | [
"freshwater_surface",
"pore_water"
] | [
"hydrological_partitioning_and_runoff",
"groundwater_flow_and_transport"
] | hillslope_to_catchment | Global and Representative Regional Observatories | synoptic_to_seasonal | Anthropocene | [
"high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge",
"nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions"
] | [
"paradoxical rapid mobilization of 'old' pre-event stored water during storm hydrograph peaks"
] | [
"Kirchner dynamical catchment storage-discharge sensitivity $g(Q) = dQ/dS = (-dQ/dt) / (Q - P + E)$ and power-law recession $-dQ/dt = a Q^b$",
"master transit-time StorAge Selection (SAS) transport $\\partial_t S_T(T, t) + \\partial_T S_T(T, t) = J(t) - Q(t) \\Omega_Q(S_T, t) - E(t) \\Omega_E(S_T, t)$"
] | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 19); corroborated across Wu et al. (2026) and Cavelan et al. (2025). Remains open due to coupled convective vs. stratiform storm hyetographs, antecedent soil moisture, and seasonal potential evapotranspiration and bedro... | Co-located observations of high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge and nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions across Global and Representative Regional Observatories coupl... | open | model_structural_uncertainty | OPEN-VERIFIED | true | hard | 4 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-014354",
"UEARTH-000165",
"UEARTH-005115"
] | [
"10.1080/02626667.2019.1620507",
"10.1002/eco.70276",
"10.1016/j.scitotenv.2025.181070",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Modeling Methods (UPH 19), DOI:10.1080/02626667.2019.1620507",
"Wu et al. (2026), Ecohydrology, DOI:10.1002/eco.70276",
"Cavelan et al. (2025), The Science of the total environment, DOI:10.1016/j.scitotenv.2025.181070",
"B. A... |
UEARTH-000047 | 47 | Disentangling Structural, Parameter, and Input Uncertainty in Hydrological Predictions (UPH 20) | How can structural model inadequacy, parameter equifinality, and precipitation/evapotranspiration forcing errors be rigorously separated and reduced in catchment hydrological predictions? | How can hydrologists separate errors caused by flawed rainfall data from errors caused by incomplete model equations? | In multi-hypothesis catchment modeling frameworks, what diagnostic signatures in flow-duration curves, tracer breakthrough tails, and energy-balance residuals uniquely isolate forcing bias from structural process misrepresentation (governed by master transit-time StorAge Selection (SAS) transport $\partial_t S_T(T, t) ... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | catchment_runoff_transit_time_uph | 2 | [
"mechanism",
"observability"
] | [
"river",
"vadose_zone"
] | [
"freshwater_surface",
"pore_water"
] | [
"hydrological_partitioning_and_runoff",
"groundwater_flow_and_transport"
] | hillslope_to_catchment | Global and Representative Regional Observatories | synoptic_to_seasonal | Anthropocene | [
"high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge",
"nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions"
] | [
"emergent catchment-scale storage-discharge constitutive relations from heterogeneous hillslope preferential flow"
] | [
"Kirchner dynamical catchment storage-discharge sensitivity $g(Q) = dQ/dS = (-dQ/dt) / (Q - P + E)$ and power-law recession $-dQ/dt = a Q^b$",
"master transit-time StorAge Selection (SAS) transport $\\partial_t S_T(T, t) + \\partial_T S_T(T, t) = J(t) - Q(t) \\Omega_Q(S_T, t) - E(t) \\Omega_E(S_T, t)$"
] | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 20); corroborated across Giudice et al. (2016) and Li et al. (2026). Remains open due to coupled convective vs. stratiform storm hyetographs, antecedent soil moisture, and seasonal potential evapotranspiration and bedro... | Co-located observations of high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge and nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions across Global and Representative Regional Observatories coupl... | open | framework_dependent | OPEN-VERIFIED | true | medium | 3 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-013453",
"UEARTH-000008",
"UEARTH-005279"
] | [
"10.1080/02626667.2019.1620507",
"10.1002/2015wr017871",
"10.5194/hess-30-6115-2026",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Modeling Methods (UPH 20), DOI:10.1080/02626667.2019.1620507",
"Giudice et al. (2016), Water Resources Research, DOI:10.1002/2015wr017871",
"Li et al. (2026), Hydrology and earth system sciences, DOI:10.5194/hess-30-6115-2026",... |
UEARTH-000048 | 48 | Deterministic Versus Stochastic Predictability Limits of Hydrological Extremes (UPH 21) | To what extent are extreme catchment floods and multi-year droughts deterministically predictable from initial boundary conditions versus fundamentally governed by stochastic threshold crossings? | Are extreme floods and droughts predictable from initial soil and weather conditions, or are they fundamentally random beyond a short horizon? | Across basin scales and hydroclimatic regimes, where does the predictability horizon transition from initial-value soil/snow/aquifer memory dominance to chaotic synoptic atmospheric forcing and sub-grid convective stochasticity (governed by Kirchner dynamical catchment storage-discharge sensitivity $g(Q) = dQ/dS = (-dQ... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | catchment_runoff_transit_time_uph | 2 | [
"mechanism",
"threshold"
] | [
"river",
"vadose_zone"
] | [
"freshwater_surface",
"pore_water"
] | [
"hydrological_partitioning_and_runoff",
"groundwater_flow_and_transport"
] | hillslope_to_catchment | Global and Representative Regional Observatories | synoptic_to_seasonal | Holocene | [
"high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge",
"nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions"
] | [
"paradoxical rapid mobilization of 'old' pre-event stored water during storm hydrograph peaks"
] | [
"Kirchner dynamical catchment storage-discharge sensitivity $g(Q) = dQ/dS = (-dQ/dt) / (Q - P + E)$ and power-law recession $-dQ/dt = a Q^b$",
"master transit-time StorAge Selection (SAS) transport $\\partial_t S_T(T, t) + \\partial_T S_T(T, t) = J(t) - Q(t) \\Omega_Q(S_T, t) - E(t) \\Omega_E(S_T, t)$"
] | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 21); corroborated across Cavelan et al. (2025) and Mei et al. (2026). Remains open due to coupled convective vs. stratiform storm hyetographs, antecedent soil moisture, and seasonal potential evapotranspiration and bedr... | Co-located observations of high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge and nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions across Global and Representative Regional Observatories coupl... | open | scale_dependent_disagreement | OPEN-VERIFIED | true | hard | 4 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-000009",
"UEARTH-013430",
"UEARTH-000122"
] | [
"10.1080/02626667.2019.1620507",
"10.1016/j.scitotenv.2025.181070",
"10.3390/f17080986",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Modeling Methods (UPH 21), DOI:10.1080/02626667.2019.1620507",
"Cavelan et al. (2025), The Science of the total environment, DOI:10.1016/j.scitotenv.2025.181070",
"Mei et al. (2026), Forests, DOI:10.3390/f17080986",
"B. Arhei... |
UEARTH-000049 | 49 | Synergistic Value of Co-Evolving Process-Based Hydrological Theory and Machine Learning (UPH 22) | How can conservation laws of mass, momentum, and energy be embedded with differentiable machine learning to discover missing constitutive relations in hydrology rather than merely fitting black-box regressions? | How can physics-informed machine learning help discover new hydrological equations rather than just fitting historical river data? | In hybrid differentiable hydrological models, can neural parameterizations constrained by mass/energy conservation and monotonicity identify universal closure relations for subsurface storage-discharge and canopy conductance across diverse basins (governed by master transit-time StorAge Selection (SAS) transport $\part... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | catchment_runoff_transit_time_uph | 2 | [
"mechanism"
] | [
"river",
"vadose_zone"
] | [
"freshwater_surface",
"pore_water"
] | [
"hydrological_partitioning_and_runoff",
"groundwater_flow_and_transport"
] | hillslope_to_catchment | Global and Representative Regional Observatories | synoptic_to_seasonal | Anthropocene | [
"high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge",
"nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions"
] | [
"emergent catchment-scale storage-discharge constitutive relations from heterogeneous hillslope preferential flow"
] | [
"Kirchner dynamical catchment storage-discharge sensitivity $g(Q) = dQ/dS = (-dQ/dt) / (Q - P + E)$ and power-law recession $-dQ/dt = a Q^b$",
"master transit-time StorAge Selection (SAS) transport $\\partial_t S_T(T, t) + \\partial_T S_T(T, t) = J(t) - Q(t) \\Omega_Q(S_T, t) - E(t) \\Omega_E(S_T, t)$"
] | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 22); corroborated across Zhu et al. (2026) and Yoo et al. (2025). Remains open due to coupled convective vs. stratiform storm hyetographs, antecedent soil moisture, and seasonal potential evapotranspiration and bedrock ... | Co-located observations of high-frequency stream and precipitation stable water isotopes (delta-18O, delta-2H), electrical conductivity, and discharge and nested hillslope tensiometer/piezometer networks and StorAge Selection (SAS) transit-time distributions across Global and Representative Regional Observatories coupl... | open | active_debate | OPEN-VERIFIED | true | medium | 3 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-014708",
"UEARTH-014622",
"UEARTH-005625"
] | [
"10.1080/02626667.2019.1620507",
"10.1016/j.watres.2026.126739",
"10.1186/s40562-025-00388-4",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Modeling Methods (UPH 22), DOI:10.1080/02626667.2019.1620507",
"Zhu et al. (2026), Water research, DOI:10.1016/j.watres.2026.126739",
"Yoo et al. (2025), Geoscience Letters, DOI:10.1186/s40562-025-00388-4",
"B. Arheimer, C. C... |
UEARTH-000050 | 50 | Feedbacks Between Scientific Hydrological Information and Societal Water Adaptation (UPH 23) | How do the physical structure of hydrological uncertainty and the timing of extreme-event attribution alter institutional and community adaptation trajectories in coupled river basins? | How do uncertainties in flood and drought forecasts change how communities adapt to changing water risks? | Within coupled socio-hydrological systems, how do ensemble forecast spread, false-alarm ratios, and nonstationary return-period updates feed back onto floodplain occupancy and groundwater withdrawal dynamics (governed by 3D transient groundwater flow $S_s \partial_t h = \nabla \cdot (\mathbf{K} \nabla h) + W$ and Cubic... | hydrology_groundwater_water_cycle | 11 | Hydrology, Groundwater, and the Water Cycle | groundwater_aquifer_karst_fractured_flow | 2 | [
"mechanism",
"reconstruction"
] | [
"aquifer",
"groundwater"
] | [
"groundwater",
"sedimentary_rock"
] | [
"groundwater_flow_and_transport",
"hydrological_partitioning_and_runoff"
] | river_basin_or_aquifer | Global and Representative Regional Observatories | interannual_to_decadal | Holocene | [
"multi-level monitoring well piezometric heads, GRACE/GRACE-FO terrestrial water storage anomalies, and InSAR aquifer deformation",
"environmental age tracers (3H/3He, 14C, 85Kr, 36Cl, noble gases) and cross-borehole hydraulic tomography"
] | [
"upscaling of hydraulic conductivity and anomalous non-Fickian solute dispersion from pore to regional aquifer scales"
] | [
"3D transient groundwater flow $S_s \\partial_t h = \\nabla \\cdot (\\mathbf{K} \\nabla h) + W$ and Cubic Law fracture transmissivity $T_f = (\\rho g b^3) / (12 \\mu)$",
"dual-domain mobile-immobile solute transport $\\theta_m \\partial_t C_m + \\theta_{im} \\partial_t C_{im} = \\nabla \\cdot (\\theta_m \\mathbf{... | Formulated in Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019, UPH 23); corroborated across Wheater (2025) and Legass et al. (2026). Remains open due to coupled episodic wet-year recharge pulses, anthropogenic groundwater abstraction, and multi-year drought and aquitard confining conti... | Co-located observations of multi-level monitoring well piezometric heads, GRACE/GRACE-FO terrestrial water storage anomalies, and InSAR aquifer deformation and environmental age tracers (3H/3He, 14C, 85Kr, 36Cl, noble gases) and cross-borehole hydraulic tomography across Global and Representative Regional Observatories... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | medium | 3 | 2,019 | G. Blöschl, M. F. P. Bierkens | 2026-10-16T00:00:00 | [
"UEARTH-013832",
"UEARTH-013835",
"UEARTH-014948"
] | [
"10.1080/02626667.2019.1620507",
"10.1016/j.envsoft.2025.106561",
"10.1016/j.envc.2026.101523",
"10.1080/02626667.2024.2355202"
] | [
"Twenty-three unsolved problems in hydrology (UPH) - a community perspective (2019), Interfaces with Society (UPH 23), DOI:10.1080/02626667.2019.1620507",
"Wheater (2025), Environmental Modelling & Software, DOI:10.1016/j.envsoft.2025.106561",
"Legass et al. (2026), Environmental Challenges, DOI:10.1016/j.envc.... |
UEARTH-000051 | 51 | Geochemical and Planetary Conditions Enabling the Origin and Early Evolution of Life (Earth in Time Q6) | What Hadean-Archean planetary boundary conditions, hydrothermal or subaerial wet-dry geochemical environments, and mineral catalytic surfaces enabled prebiotic synthesis and the emergence of Earth's earliest biosphere? | What geological environments and mineral reactions on early Earth allowed non-living chemicals to assemble into the first living organisms? | Between $4.4\,\mathrm{Ga}$ and $3.7\,\mathrm{Ga}$, did serpentinizing alkaline hydrothermal vents, impact-generated subaerial hydrothermal ponds, or volcanic lightning-driven atmospheric synthesis provide the thermodynamic gradients and phosphorus/transition-metal catalysis required for prebiotic carbon fixation? | geologic_time_paleoclimate_stratigraphy_earth_history | 4 | Geologic Time, Paleoclimate, Stratigraphy, and Earth History | precambrian_oxygenation_early_earth | 1 | [
"mechanism",
"reconstruction"
] | [
"sedimentary_stratigraphic_archive",
"atmosphere"
] | [
"sedimentary_rock",
"marine_sediment"
] | [
"redox_transformation",
"carbon_cycle_and_biogeochemical_cycling"
] | planetary_global | Global and Representative Regional Observatories | billion_year_planetary | Precambrian | [
"mass-independent sulfur isotopes (Delta33S), iron speciation, and Ce/Mo/U/Cr redox-sensitive trace-metal shales",
"carbonate-associated sulfate and detrital redox-sensitive mineral assemblages"
] | [
"links between supercontinent cycles, nutrient phosphorus availability, and early biospheric evolution"
] | [
"global redox-carbon burial balance $F_{\\mathrm{O2,source}} = F_{\\mathrm{total\\,C}} \\cdot f_{\\mathrm{org}}(\\delta^{13}\\mathrm{C}) + F_{\\mathrm{pyr}} - F_{\\mathrm{volc\\,red}} - F_{\\mathrm{ox\\,weath}}(p\\mathrm{O}_2)$",
"planetary radiative balance $(S_\\odot(t)/4)(1 - A_p) = \\mathrm{OLR}(T_s, p\\mathr... | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, Question 6); corroborated across Avice et al. (2017) and Choudhuri et al. (2020). Remains open due to coupled oxygenic photosynthesis evolution, mantle reducer outgassing decline, and Snowball Earth glaciations and continental emergence area,... | Co-located observations of mass-independent sulfur isotopes (Delta33S), iron speciation, and Ce/Mo/U/Cr redox-sensitive trace-metal shales and carbonate-associated sulfate and detrital redox-sensitive mineral assemblages across Global and Representative Regional Observatories coupled with process-resolving models of re... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | very_hard | 5 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-003823",
"UEARTH-003889",
"UEARTH-002687"
] | [
"10.17226/25761",
"10.1038/ncomms15455",
"10.2465/jmps.190827a",
"10.1126/science.aay3701"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Priority Questions (Question 6), DOI:10.17226/25761",
"Avice et al. (2017), Nature communications, DOI:10.1038/ncomms15455",
"Choudhuri et al. (2020), Journal of Mineralogical and Petrological Sciences, DOI:10.2465/jmps.190827a",
"J. E. Tierney... |
UEARTH-000052 | 52 | Consequences of Biodiversity Loss and Biotic Turnover for Earth System Processes (Earth in Time Q7) | How do mass extinctions, functional biodiversity loss, and biome reorganizations alter physical and geochemical Earth system processes including weathering rates, sediment transport, and carbon-nutrient cycling? | How does the loss of plant, animal, and microbial species change how Earth erodes rock, moves sediment, and cycles carbon? | Across both Phanerozoic mass extinction intervals and modern Anthropocene defaunation/land-cover change, what is the quantitative sensitivity of soil bioturbation, fluvial bank cohesion, marine biological pump efficiency, and silicate weathering to taxonomic and functional diversity loss (governed by Sperry-Tyree xylem... | ecosystem_earth_interactions_land_change | 13 | Ecosystem-Earth Interactions, Land Change, and Environmental Response | forest_mortality_drought_carbon_sink | 1 | [
"mechanism",
"transport"
] | [
"forest",
"biosphere_terrestrial"
] | [
"biota",
"tropospheric_air"
] | [
"ecosystem_disturbance_and_biophysical_feedback",
"carbon_cycle_and_biogeochemical_cycling"
] | continental | Global and Representative Regional Observatories | interannual_to_decadal | Anthropocene | [
"FLUXNET eddy-covariance NEE/GPP time series, RAINFOR/ForestGEO permanent census plots, and satellite SIF/VOD",
"xylem vulnerability curves (P50/P88), non-structural carbohydrate (NSC) assays, and GEDI spaceborne LiDAR biomass"
] | [
"physiological thresholds separating xylem hydraulic failure from carbon starvation during multi-year mega-droughts"
] | [
"Sperry-Tyree xylem hydraulic conductance $K(\\psi) = K_{\\max} \\exp[-(-\\psi / b)^c]$ with critical cavitation threshold $\\psi_{50} / \\psi_{88}$",
"Farquhar-Medlyn coupled photosynthesis-conductance $A_n = \\min(A_c(V_{c\\max}, C_i), A_j(J_{\\max}, C_i)) - R_d$ with $g_s = g_0 + 1.6(1 + g_1/\\sqrt{\\mathrm{VP... | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, Question 7); corroborated across Repasch et al. (2021) and Armstrong et al. (2015). Remains open due to coupled atmospheric vapor pressure deficit (VPD) extremes, heatwaves, and elevated atmospheric CO2 and plant hydraulic trait diversity (is... | Co-located observations of FLUXNET eddy-covariance NEE/GPP time series, RAINFOR/ForestGEO permanent census plots, and satellite SIF/VOD and xylem vulnerability curves (P50/P88), non-structural carbohydrate (NSC) assays, and GEDI spaceborne LiDAR biomass across Global and Representative Regional Observatories coupled wi... | open | mechanism_known_magnitude_uncertain | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-016070",
"UEARTH-000244",
"UEARTH-008056"
] | [
"10.17226/25761",
"10.1038/s41561-021-00845-7",
"10.1007/s10021-015-9907-4",
"10.1038/s43017-020-0085-3"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Priority Questions (Question 7), DOI:10.17226/25761",
"Repasch et al. (2021), Nature Geoscience, DOI:10.1038/s41561-021-00845-7",
"Armstrong et al. (2015), Ecosystems, DOI:10.1007/s10021-015-9907-4",
"D. M. J. S. Bowman, C. A. Kolden, J. T. Aba... |
UEARTH-000053 | 53 | Southern Ocean Eddy Saturation and Overturning Response to Intensified Westerly Winds (SCAR Horizon Scan) | To what extent do mesoscale baroclinic eddies in the Antarctic Circumpolar Current saturate horizontal transport and compensate Eulerian wind-driven overturning under poleward-intensifying Southern Hemisphere westerly winds? | Why don't stronger winds around Antarctica speed up the main Southern Ocean current as much as simple physics predicts, and how do ocean eddies absorb that wind energy? | In the Southern Ocean across rough bathymetric ridges, what governs the partitioning of increased wind-stress momentum input into transient mesoscale eddy kinetic energy, bottom form stress, and residual overturning circulation ($\Psi_{\mathrm{res}}$) upwelled carbon outgassing? | physical_oceanography_ocean_circulation | 9 | Physical Oceanography and Ocean Circulation | mesoscale_submesoscale_eddies_fronts | 5 | [
"mechanism",
"predictability"
] | [
"open_ocean",
"sea_surface"
] | [
"seawater",
"dissolved_phase"
] | [
"ocean_circulation_and_mixing",
"radiative_transfer_and_energy_balance"
] | ocean_basin_or_gyre | Antarctica and the Southern Ocean | synoptic_to_seasonal | Anthropocene | [
"SWOT wide-swath interferometer sea-surface height, surface drifter dispersion arrays, and glider high-resolution sections",
"shipboard ADCP velocity shear profiles and eddy-resolving (1/12° to 1/48°) ocean general circulation models"
] | [
"scale-aware eddy diffusivity/backscatter parameterizations and western-boundary-current separation mechanics"
] | [
"quasi-geostrophic potential vorticity conservation $D_g q_{\\mathrm{QG}}/Dt = 0$ where $q_{\\mathrm{QG}} = \\nabla_h^2 \\psi + f + \\partial_z [(f_0^2 / N^2) \\partial_z \\psi]$",
"submesoscale Ertel potential vorticity $q = (f \\hat{\\mathbf{z}} + \\nabla \\times \\mathbf{u}) \\cdot \\nabla b \\le 0$ criterion ... | Formulated in A horizon scan of Antarctic and Southern Ocean science for the next two decades (2015, SCAR Q18); corroborated across Stewart et al. (2021) and Liu et al. (2024). Remains open due to coupled wind-stress curl, surface buoyancy loss, and lateral density gradients across ocean fronts and continental slope to... | Co-located observations of SWOT wide-swath interferometer sea-surface height, surface drifter dispersion arrays, and glider high-resolution sections and shipboard ADCP velocity shear profiles and eddy-resolving (1/12° to 1/48°) ocean general circulation models across Antarctica and the Southern Ocean coupled with proce... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,015 | M. C. Kennicutt II, S. L. Chown | 2026-10-16T00:00:00 | [
"UEARTH-011196",
"UEARTH-010910",
"UEARTH-009958"
] | [
"10.1017/S0954102014000674",
"10.1029/2021gl094569",
"10.1029/2023gl106747",
"10.17226/27846"
] | [
"A horizon scan of Antarctic and Southern Ocean science for the next two decades (2015), Southern Ocean and Sea Ice (SCAR Q18), DOI:10.1017/S0954102014000674",
"Stewart et al. (2021), Geophysical Research Letters, DOI:10.1029/2021gl094569",
"Liu et al. (2024), Geophysical Research Letters, DOI:10.1029/2023gl106... |
UEARTH-000054 | 54 | Inner-Core Nucleation Age and the Paleomagnetic Field Intensity Paradox | What physical, chemical, and dynamical mechanisms determine when Earth's solid inner core first nucleated ($0.5\text{--}1.5\,\mathrm{Ga}$) and why paleomagnetic dipole intensity did not exhibit a step-function increase at nucleation onset? | What natural processes explain when Earth's solid inner core first froze and how the magnetic field stayed active beforehand? | How can Precambrian single-crystal Thellier-Thellier paleointensity records and diamond-anvil Fe-alloy thermal conductivity ($k_c$) constrain outer-core entropy balance $Q_{\mathrm{CMB}} = Q_s + Q_L + Q_g$ and magnetic Reynolds number $\mathrm{Rm} = \mu_0 \sigma U L \gg 10^2$ to resolve when Earth's solid inner core fi... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | core_dynamo_inner_core | 1 | [
"mechanism",
"reconstruction"
] | [
"inner_core",
"outer_core"
] | [
"core_alloy",
"melt"
] | [
"geomagnetic_dynamo",
"mantle_convection"
] | mantle_or_core_domain | Planetary Deep Interior (Inner and Outer Core) | millennial_to_orbital | Precambrian | [
"PKIKP body-wave travel-time residuals and normal-mode splitting functions",
"satellite and paleomagnetic secular-variation field reconstructions"
] | [
"inner-core crystalline anisotropy, light-element partitioning, and outer-core convective buoyancy flux"
] | [
"magnetic induction $\\partial_t \\mathbf{B} = \\nabla \\times (\\mathbf{u} \\times \\mathbf{B}) + \\eta_m \\nabla^2 \\mathbf{B}$ at $\\mathrm{Ek} \\sim 10^{-15}$ and $\\mathrm{Pm} \\sim 10^{-6}$",
"Elsasser number $\\Lambda = \\sigma B^2 / (\\rho \\Omega) \\sim O(1)$ and thermochemical buoyancy flux $F_B = F_T +... | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q1b); corroborated across Sun et al. (2023) and Kolesnikov et al. (2025). Remains open due to coupled inner-core crystallization buoyancy flux and secular core cooling and core-mantle boundary topography and heterogeneous lower-mantle the... | Co-located observations of PKIKP body-wave travel-time residuals and normal-mode splitting functions and satellite and paleomagnetic secular-variation field reconstructions across Planetary Deep Interior (Inner and Outer Core) coupled with process-resolving models of geomagnetic dynamo to constrain inner-core crystalli... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | very_hard | 5 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-000066",
"UEARTH-000055",
"UEARTH-000114"
] | [
"10.17226/25761",
"10.1038/s41467-023-37376-1",
"10.1038/s41467-025-67067-y",
"10.17226/25761"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Priority Questions (EiT-Q1b), DOI:10.17226/25761",
"Sun et al. (2023), Nature Communications, DOI:10.1038/s41467-023-37376-1",
"Kolesnikov et al. (2025), Nature Communications, DOI:10.1038/s41467-025-67067-y",
"NASEM (2020), A Vision for NSF Ea... |
UEARTH-000055 | 55 | Stratified Layer Thickness and Light-Element Buoyancy at the Top of the Outer Core | What physical, chemical, and dynamical mechanisms determine whether a compositionally or thermally stratified layer (the $E'$ layer) persists beneath the core-mantle boundary and how barodiffusion of $\mathrm{Si, O, S, C, H}$ sustains it against convective mixing? | What natural processes determine whether a thin buoyant liquid layer sits at the very top of Earth's outer core? | How can SmKS multiphase body-wave differential travel times and 6-year geomagnetic secular variation periodicities constrain Brunt-Väisälä buoyancy frequency $N^2 = -(g/\rho_0)(\partial \rho / \partial r)_{\mathrm{ad}} \ge 0$ and MAC wave dispersion to resolve whether a compositionally or thermally stratified layer (t... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | core_dynamo_inner_core | 1 | [
"mechanism"
] | [
"inner_core",
"outer_core"
] | [
"core_alloy",
"melt"
] | [
"geomagnetic_dynamo",
"mantle_convection"
] | mantle_or_core_domain | Planetary Deep Interior (Inner and Outer Core) | millennial_to_orbital | Quaternary | [
"PKIKP body-wave travel-time residuals and normal-mode splitting functions",
"satellite and paleomagnetic secular-variation field reconstructions"
] | [
"core-mantle boundary heat-flux heterogeneity and geomagnetic reversal thresholds"
] | [
"magnetic induction $\\partial_t \\mathbf{B} = \\nabla \\times (\\mathbf{u} \\times \\mathbf{B}) + \\eta_m \\nabla^2 \\mathbf{B}$ at $\\mathrm{Ek} \\sim 10^{-15}$ and $\\mathrm{Pm} \\sim 10^{-6}$",
"Elsasser number $\\Lambda = \\sigma B^2 / (\\rho \\Omega) \\sim O(1)$ and thermochemical buoyancy flux $F_B = F_T +... | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q1c); corroborated across Koelemeijer et al. (2012) and Chen et al. (2026). Remains open due to coupled inner-core crystallization buoyancy flux and secular core cooling and core-mantle boundary topography and heterogeneous lower-mantle t... | Co-located observations of PKIKP body-wave travel-time residuals and normal-mode splitting functions and satellite and paleomagnetic secular-variation field reconstructions across Planetary Deep Interior (Inner and Outer Core) coupled with process-resolving models of geomagnetic dynamo to constrain core-mantle boundary... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-000501",
"UEARTH-000066",
"UEARTH-000104"
] | [
"10.17226/25761",
"10.1111/j.1365-246x.2012.05499.x",
"10.1029/2026jb033776",
"10.17226/25761"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Priority Questions (EiT-Q1c), DOI:10.17226/25761",
"Koelemeijer et al. (2012), Geophysical Journal International, DOI:10.1111/j.1365-246x.2012.05499.x",
"Chen et al. (2026), Journal of Geophysical Research Solid Earth, DOI:10.1029/2026jb033776",
... |
UEARTH-000056 | 56 | Archean Continental Crust Generation Under Stagnant-Lid versus Subduction Regimes | What physical, chemical, and dynamical mechanisms determine whether Archean tonalite-trondhjemite-granodiorite (TTG) suites formed through warm flat-slab subduction or infracrustal melting at the base of thickened oceanic plateaus? | What natural processes determine whether Earth's earliest continents formed above subduction zones or at the base of thick volcanic plateaus? | How can Eoarchean-Mesoarchean zircon $\delta^{18}\mathrm{O}\text{--}\varepsilon_{\mathrm{Hf}}(t)$ arrays and paired metamorphic belt barometry constrain amphibolite-to-eclogite dehydration melting reactions ($P \ge 1.2\,\mathrm{GPa}$, $T \sim 850\text{--}1000\,^\circ\mathrm{C}$) and $\mathrm{La/Yb, Sr/Y}$ partitioning ... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | craton_orogen_continental_crust | 1 | [
"mechanism",
"reconstruction"
] | [
"continental_crust",
"orogen"
] | [
"crystalline_rock",
"mantle_silicate"
] | [
"crustal_deformation",
"metamorphic_transformation"
] | tectonic_plate_or_orogen | Archean–Proterozoic Cratons and Continental Orogens | multi_million_year_tectonic | Precambrian | [
"laser-ablation ICP-MS/SIMS zircon U-Pb geochronology and Lu-Hf isotope ratios",
"crustal receiver-function Moho depth maps, Bouguer gravity anomalies, and xenolith thermobarometry"
] | [
"secular continental crust growth versus recycling rates and lower-crustal foundry mechanics"
] | [
"viscous thin-sheet Argand number $\\mathrm{Ar} = g \\rho_c (1 - \\rho_c/\\rho_m) H_c^2 / (\\eta_{\\mathrm{eff}} U_0)$",
"isopycnic cratonic root stability $\\Delta \\rho(T, X_{\\mathrm{Mg\\#}}) = \\rho_0 [ -\\alpha (T - T_0) + \\beta_{\\mathrm{chem}} \\Delta X_{\\mathrm{Mg\\#}} ] \\approx 0$"
] | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q2b); corroborated across Fan et al. (2026) and Dai et al. (2020). Remains open due to coupled continental collision, lithospheric thickening, and convective removal of eclogitized lower crust and Moho temperature, crustal radiogenic heat... | Co-located observations of laser-ablation ICP-MS/SIMS zircon U-Pb geochronology and Lu-Hf isotope ratios and crustal receiver-function Moho depth maps, Bouguer gravity anomalies, and xenolith thermobarometry across Archean–Proterozoic Cratons and Continental Orogens coupled with process-resolving models of crustal defo... | open | active_debate | OPEN-VERIFIED | true | very_hard | 5 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-000065",
"UEARTH-000510",
"UEARTH-000091"
] | [
"10.17226/25761",
"10.1038/s41598-025-29212-x",
"10.1029/2019jb019164",
"10.17226/25761"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Priority Questions (EiT-Q2b), DOI:10.17226/25761",
"Fan et al. (2026), Scientific Reports, DOI:10.1038/s41598-025-29212-x",
"Dai et al. (2020), Journal of Geophysical Research Solid Earth, DOI:10.1029/2019jb019164",
"NASEM (2020), A Vision for ... |
UEARTH-000057 | 57 | Grain-Damage Rheology and Memory of Inherited Plate-Boundary Weakening | What physical, chemical, and dynamical mechanisms determine how two-phase grain-size pinning (Zener pinning) in polymineralic mantle mylonites preserves lithospheric shear zones over $10^8\,\mathrm{yr}$ supercontinent cycles? | What natural processes determine how ancient tectonic plate boundaries stay weak for hundreds of millions of years? | How can exhumed peridotite mylonite EBSD microstructural fabrics and Pn/Sn azimuthal seismic anisotropy constrain coupled grain-damage evolution $d r / dt = G_{\mathrm{growth}}(T, r) - D_{\mathrm{damage}}(\sigma — \dot{\varepsilon}, r)$ and diffusion/dislocation creep partitioning to resolve how two-phase grain-size pi... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | subduction_slab_mantle_wedge | 1 | [
"mechanism"
] | [
"subduction_zone",
"upper_mantle"
] | [
"crystalline_rock",
"magma_or_melt"
] | [
"plate_subduction",
"magma_generation_and_ascent"
] | tectonic_plate_or_orogen | Circum-Pacific and Tethyan Subduction Margins | multi_million_year_tectonic | Cenozoic | [
"high-resolution slab-interface seismic attenuation and magnetotelluric conductivity profiles",
"arc-lava volatile ratios, oxygen fugacity (fO2) oxybarometry, and slab-fluid trace-element signatures"
] | [
"mechanical coupling and metamorphic dehydration kinetics along the plate interface"
] | [
"composite dislocation-diffusion creep $\\dot{\\varepsilon}_{ij} = (A_{\\mathrm{dis}} \\tau_E^{n-1} + A_{\\mathrm{diff}} d^{-p}) C_{\\mathrm{OH}}^r \\exp[-(E^* + P V^*)/RT] \\tau_{ij}$",
"slab thermal parameter $\\Phi_{\\mathrm{slab}} = t_{\\mathrm{age}} v_{\\mathrm{conv}} \\sin\\theta$ governing dehydration reac... | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q2c); corroborated across Fuchs et al. (2020) and Fuchs et al. (2019). Remains open due to coupled slab pull, trench rollback, and metamorphic dehydration reactions and slab thermal age, incoming plate hydration state, and overriding-plat... | Co-located observations of high-resolution slab-interface seismic attenuation and magnetotelluric conductivity profiles and arc-lava volatile ratios, oxygen fugacity (fO2) oxybarometry, and slab-fluid trace-element signatures across Circum-Pacific and Tethyan Subduction Margins coupled with process-resolving models of ... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-000067",
"UEARTH-000348",
"UEARTH-000104"
] | [
"10.17226/25761",
"10.1029/2020jb020335",
"10.1093/gji/ggz167",
"10.17226/25761"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Priority Questions (EiT-Q2c), DOI:10.17226/25761",
"Fuchs et al. (2020), Journal of Geophysical Research Solid Earth, DOI:10.1029/2020jb020335",
"Fuchs et al. (2019), Geophysical Journal International, DOI:10.1093/gji/ggz167",
"NASEM (2020), A ... |
UEARTH-000058 | 58 | Origin and Melt Fraction of Ultra-Low Velocity Zones (ULVZs) at the Core-Mantle Boundary | What physical, chemical, and dynamical mechanisms determine whether patchy Ultra-Low Velocity Zones (ULVZs) at the base of the mantle represent iron-enriched basal magma ocean remnants, core-derived reaction products, or partial melting of subducted mid-ocean ridge basalt? | What natural processes determine what causes thin patches at the bottom of the mantle where seismic waves slow down by up to 30%? | How can core-diffracted $SPdKS$, $ScP$, and $PKP$ precursor waveform modeling constrain compressional/shear velocity reductions ($\delta \ln V_S — \delta \ln V_P \approx 3 — 1$) and dihedral wetting angle $\theta_{\mathrm{melt}}$ to resolve whether patchy Ultra-Low Velocity Zones (ULVZs) at the base of the mantle repre... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | core_dynamo_inner_core | 1 | [
"mechanism",
"budget"
] | [
"inner_core",
"outer_core"
] | [
"core_alloy",
"melt"
] | [
"geomagnetic_dynamo",
"mantle_convection"
] | mantle_or_core_domain | Planetary Deep Interior (Inner and Outer Core) | millennial_to_orbital | Quaternary | [
"PKIKP body-wave travel-time residuals and normal-mode splitting functions",
"satellite and paleomagnetic secular-variation field reconstructions"
] | [
"inner-core crystalline anisotropy, light-element partitioning, and outer-core convective buoyancy flux"
] | [
"magnetic induction $\\partial_t \\mathbf{B} = \\nabla \\times (\\mathbf{u} \\times \\mathbf{B}) + \\eta_m \\nabla^2 \\mathbf{B}$ at $\\mathrm{Ek} \\sim 10^{-15}$ and $\\mathrm{Pm} \\sim 10^{-6}$",
"Elsasser number $\\Lambda = \\sigma B^2 / (\\rho \\Omega) \\sim O(1)$ and thermochemical buoyancy flux $F_B = F_T +... | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q3b); corroborated across Zhang et al. (2024) and Li et al. (2017). Remains open due to coupled inner-core crystallization buoyancy flux and secular core cooling and core-mantle boundary topography and heterogeneous lower-mantle thermal c... | Co-located observations of PKIKP body-wave travel-time residuals and normal-mode splitting functions and satellite and paleomagnetic secular-variation field reconstructions across Planetary Deep Interior (Inner and Outer Core) coupled with process-resolving models of geomagnetic dynamo to constrain inner-core crystalli... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-001170",
"UEARTH-000516",
"UEARTH-000088"
] | [
"10.17226/25761",
"10.1073/pnas.2406386121",
"10.1038/s41467-017-00219-x",
"10.17226/25761"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Deep Earth Structure (EiT-Q3b), DOI:10.17226/25761",
"Zhang et al. (2024), Proceedings of the National Academy of Sciences of the United States of America, DOI:10.1073/pnas.2406386121",
"Li et al. (2017), Nature communications, DOI:10.1038/s41467... |
UEARTH-000059 | 59 | Slab Stagnation versus Penetration Across the 660-km Ringwoodite Dissociation Boundary | What physical, chemical, and dynamical mechanisms determine what combination of endothermic Clapeyron slope resistance, viscosity jump ($\Delta \eta_{660}$), and trench rollback velocity causes some subducted slabs to stagnate in the Mantle Transition Zone while others penetrate into the lower mantle? | What natural processes determine why some sinking tectonic plates stall at 660 km depth while others plunge straight into the lower mantle? | How can P- and S-wave full-waveform mantle tomography and SS/PP precursor discontinuity topography constrain Clapeyron slope $\gamma_{660} = dP/dT \approx -1.3\text{ to }-2.5\,\mathrm{MPa\,K^{-1}}$ and buoyancy number $B = \Delta \rho_{\mathrm{phase}} / (\rho \alpha \Delta T)$ to resolve what combination of endothermic... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | lower_mantle_plumes_transition_zone | 1 | [
"mechanism",
"rate"
] | [
"lower_mantle",
"transition_zone"
] | [
"mantle_silicate",
"rock"
] | [
"mantle_convection",
"metamorphic_transformation"
] | mantle_or_core_domain | Global Mantle Transition Zone and Lower Mantle | multi_million_year_tectonic | Cenozoic | [
"broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements",
"full-waveform seismic tomography and P-to-S receiver-function discontinuity depths"
] | [
"mantle transition-zone water storage capacity and viscosity stratification across 660 km"
] | [
"Clapeyron slope $dP/dT = \\Delta S / \\Delta V$ across the $410\\,\\mathrm{km}$ ($\\gamma > 0$) and $660\\,\\mathrm{km}$ ($\\gamma \\le 0$) phase boundaries",
"thermochemical buoyancy ratio $B = \\Delta \\rho_{\\mathrm{chem}} / (\\rho_0 \\alpha \\Delta T)$ and Rayleigh number $\\mathrm{Ra} = \\rho g \\alpha \\De... | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q3c); corroborated across Dai et al. (2020) and Wu et al. (2026). Remains partially solved due to coupled thermochemical mantle convection and deep slab negative buoyancy and endothermic 660-km phase-transition clapeyron slopes and basal... | Co-located observations of broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements and full-waveform seismic tomography and P-to-S receiver-function discontinuity depths across Global Mantle Transition Zone and Lower Mantle coupled with process-resolving models of mantle conve... | partially_solved | mechanism_known_magnitude_uncertain | PARTIAL-PROGRESS | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-000324",
"UEARTH-000396",
"UEARTH-000088"
] | [
"10.17226/25761",
"10.1029/2019jb019164",
"10.1093/petrology/egag080",
"10.17226/25761"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Deep Earth Structure (EiT-Q3c), DOI:10.17226/25761",
"Dai et al. (2020), Journal of Geophysical Research Solid Earth, DOI:10.1029/2019jb019164",
"Wu et al. (2026), Journal of Petrology, DOI:10.1093/petrology/egag080",
"NASEM (2020), A Vision fo... |
UEARTH-000060 | 60 | Magmatic versus Amagmatic Extension Partitioning at Ultra-Slow Spreading Ridges | What physical, chemical, and dynamical mechanisms determine how lithospheric thermal structure and serpentinization feedback govern flip-flop detachment faulting and amagmatic mantle exhumation along ultra-slow spreading mid-ocean ridges? | What natural processes determine how tectonic plates pull apart at ultra-slow mid-ocean ridges where very little magma is present? | How can ocean-bottom seismometer microseismicity, seafloor drilling of oceanic core complexes, and marine magnetic anomalies constrain magmatic fraction $M \in [0, 1]$ balancing plate separation velocity $v_{\mathrm{spread}}$ against dike opening rate to resolve how lithospheric thermal structure and serpentinization f... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | craton_orogen_continental_crust | 3 | [
"mechanism",
"budget"
] | [
"continental_crust",
"orogen"
] | [
"crystalline_rock",
"mantle_silicate"
] | [
"crustal_deformation",
"metamorphic_transformation"
] | tectonic_plate_or_orogen | Archean–Proterozoic Cratons and Continental Orogens | multi_million_year_tectonic | Cenozoic | [
"crustal receiver-function Moho depth maps, Bouguer gravity anomalies, and xenolith thermobarometry",
"zircon U-Pb/Hf-O isotopic arrays and whole-rock major/trace-element crustal compilations"
] | [
"secular continental crust growth versus recycling rates and lower-crustal foundry mechanics"
] | [
"viscous thin-sheet Argand number $\\mathrm{Ar} = g \\rho_c (1 - \\rho_c/\\rho_m) H_c^2 / (\\eta_{\\mathrm{eff}} U_0)$",
"isopycnic cratonic root stability $\\Delta \\rho(T, X_{\\mathrm{Mg\\#}}) = \\rho_0 [ -\\alpha (T - T_0) + \\beta_{\\mathrm{chem}} \\Delta X_{\\mathrm{Mg\\#}} ] \\approx 0$"
] | Formulated in Exploring Earth by Scientific Ocean Drilling: 2050 Science Framework (2020, IODP-SO2a); corroborated across Russell et al. (2021) and Yang et al. (2020). Remains open due to coupled continental collision, lithospheric thickening, and convective removal of eclogitized lower crust and Moho temperature, crus... | Co-located observations of crustal receiver-function Moho depth maps, Bouguer gravity anomalies, and xenolith thermobarometry and zircon U-Pb/Hf-O isotopic arrays and whole-rock major/trace-element crustal compilations across Archean–Proterozoic Cratons and Continental Orogens coupled with process-resolving models of c... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,020 | A. A. P. Koppers, R. Coggon | 2026-10-16T00:00:00 | [
"UEARTH-000065",
"UEARTH-000068",
"UEARTH-000085"
] | [
"10.6075/J0W66J9H",
"10.1029/2021jb022955",
"10.1029/2019gl086257",
"10.17226/25761"
] | [
"Exploring Earth by Scientific Ocean Drilling: 2050 Science Framework (2020), Oceanic Life Cycle (IODP-SO2a), DOI:10.6075/J0W66J9H",
"Russell et al. (2021), Journal of Geophysical Research Solid Earth, DOI:10.1029/2021jb022955",
"Yang et al. (2020), Geophysical Research Letters, DOI:10.1029/2019gl086257",
"NA... |
UEARTH-000061 | 61 | Hydrothermal Cooling Efficiency and Lower Oceanic Crust Accretion Mechanics | What physical, chemical, and dynamical mechanisms determine whether lower oceanic crust gabbroic sections accrete via a single axial magma lens ('gabbro glacier' ductile downflow) or via transcrustal stacked sill injections cooled by deep hydrothermal circulation? | What natural processes determine how the lower half of oceanic crust forms and cools beneath mid-ocean ridges? | How can deep ocean drilling of fast-spreading lower oceanic crust, plagioclase Mg-in-crystal diffusion speedometry, and seismic reflection constrain Nusselt number $\mathrm{Nu} = q_{\mathrm{hydro}} L / (k \Delta T)$ and viscous cumulate subsidence vs. conductive cooling rates to resolve whether lower oceanic crust gabb... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | continental_rifting_breakup_margins | 3 | [
"mechanism"
] | [
"rift",
"lithosphere"
] | [
"crystalline_rock",
"magma_or_melt"
] | [
"crustal_deformation",
"magma_generation_and_ascent"
] | sedimentary_basin_or_continental_margin | Continental Rift Systems and Rifted Passive Margins | multi_million_year_tectonic | Cenozoic | [
"deep-penetration marine multichannel seismic reflection and wide-angle refraction profiles",
"syn-rift basin tectono-stratigraphy, GNSS extension rates, and dike-intrusion seismicity"
] | [
"inherited structural weakness reactivation and asthenospheric decompression melt partitioning"
] | [
"Buck dike-assisted versus tectonic stretching yield $\\Delta \\sigma_{\\mathrm{magma}} = \\rho_c g z - \\rho_m g z + P_{\\mathrm{ex}} \\le \\sigma_Y(\\varepsilon, \\dot{\\varepsilon})$",
"McKenzie lithospheric thinning factor $\\beta = L / L_0$ and syn-rift isostatic subsidence $S_i(\\beta)$"
] | Formulated in Exploring Earth by Scientific Ocean Drilling: 2050 Science Framework (2020, IODP-SO2b); corroborated across Long et al. (2025) and Wang et al. (2020). Remains open due to coupled far-field plate tensional stresses and asthenospheric upwelling buoyancy and pre-existing crustal shear zones, lithospheric the... | Co-located observations of deep-penetration marine multichannel seismic reflection and wide-angle refraction profiles and syn-rift basin tectono-stratigraphy, GNSS extension rates, and dike-intrusion seismicity across Continental Rift Systems and Rifted Passive Margins coupled with process-resolving models of crustal d... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,020 | A. A. P. Koppers, R. Coggon | 2026-10-16T00:00:00 | [
"UEARTH-000351",
"UEARTH-000696",
"UEARTH-000092"
] | [
"10.6075/J0W66J9H",
"10.1126/sciadv.adt1023",
"10.1038/s41467-019-13720-2",
"10.17226/25761"
] | [
"Exploring Earth by Scientific Ocean Drilling: 2050 Science Framework (2020), Oceanic Life Cycle (IODP-SO2b), DOI:10.6075/J0W66J9H",
"Long et al. (2025), Science Advances, DOI:10.1126/sciadv.adt1023",
"Wang et al. (2020), Nature communications, DOI:10.1038/s41467-019-13720-2",
"NASEM (2020), A Vision for NSF ... |
UEARTH-000062 | 62 | Outer-Rise Bending Fault Hydration Depth in Incoming Oceanic Lithosphere | What physical, chemical, and dynamical mechanisms determine how deeply normal faults at outer-rise trench bends channel seawater into incoming oceanic mantle lithosphere prior to subduction? | What natural processes determine how deeply cracks in bending ocean plates allow seawater to soak into the mantle before the plate sinks? | How can active-source wide-angle ocean-bottom seismic $V_P/V_S$ inversions and marine controlled-source electromagnetics constrain effective normal stress $\sigma_n' = \sigma_n - P_f$ under flexural plate bending moment $M_b(x)$ and thermal cracking to resolve how deeply normal faults at outer-rise trench bends channel... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | subduction_slab_mantle_wedge | 3 | [
"mechanism"
] | [
"subduction_zone",
"upper_mantle"
] | [
"crystalline_rock",
"magma_or_melt"
] | [
"plate_subduction",
"magma_generation_and_ascent"
] | tectonic_plate_or_orogen | Circum-Pacific and Tethyan Subduction Margins | multi_million_year_tectonic | Cenozoic | [
"high-resolution slab-interface seismic attenuation and magnetotelluric conductivity profiles",
"arc-lava volatile ratios, oxygen fugacity (fO2) oxybarometry, and slab-fluid trace-element signatures"
] | [
"slab-to-wedge volatile and oxidant mass transfer rates and mantle-wedge corner-flow viscosity"
] | [
"composite dislocation-diffusion creep $\\dot{\\varepsilon}_{ij} = (A_{\\mathrm{dis}} \\tau_E^{n-1} + A_{\\mathrm{diff}} d^{-p}) C_{\\mathrm{OH}}^r \\exp[-(E^* + P V^*)/RT] \\tau_{ij}$",
"slab thermal parameter $\\Phi_{\\mathrm{slab}} = t_{\\mathrm{age}} v_{\\mathrm{conv}} \\sin\\theta$ governing dehydration reac... | Formulated in Exploring Earth by Scientific Ocean Drilling: 2050 Science Framework (2020, IODP-SO2c); corroborated across Lefeldt et al. (2012) and Mark et al. (2023). Remains open due to coupled slab pull, trench rollback, and metamorphic dehydration reactions and slab thermal age, incoming plate hydration state, and ... | Co-located observations of high-resolution slab-interface seismic attenuation and magnetotelluric conductivity profiles and arc-lava volatile ratios, oxygen fugacity (fO2) oxybarometry, and slab-fluid trace-element signatures across Circum-Pacific and Tethyan Subduction Margins coupled with process-resolving models of ... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,020 | A. A. P. Koppers, R. Coggon | 2026-10-16T00:00:00 | [
"UEARTH-000465",
"UEARTH-000309",
"UEARTH-001511"
] | [
"10.6075/J0W66J9H",
"10.1029/2012gc004043",
"10.1029/2023gl103331",
"10.17226/25761"
] | [
"Exploring Earth by Scientific Ocean Drilling: 2050 Science Framework (2020), Geodynamic Cycles (IODP-SO2c), DOI:10.6075/J0W66J9H",
"Lefeldt et al. (2012), Geochemistry Geophysics Geosystems, DOI:10.1029/2012gc004043",
"Mark et al. (2023), Geophysical Research Letters, DOI:10.1029/2023gl103331",
"NASEM (2020)... |
UEARTH-000063 | 63 | 3D Upper-Mantle Viscosity Heterogeneity Beneath West versus East Antarctica | What physical, chemical, and dynamical mechanisms determine how lateral variations of 3–4 orders of magnitude in upper-mantle viscosity between the West Antarctic rift system and the East Antarctic craton modulate rapid glacial isostatic rebound and grounding-line stability? | What natural processes determine how soft mantle rock beneath West Antarctica lifts the bedrock as ice melts and affects glacier stability? | How can dense ANET GNSS bedrock uplift velocities and POLENET broadband seismic attenuation/anisotropy tomography constrain Maxwell/Burgers viscoelastic relaxation time $\tau_M = \eta / \mu$ with $\eta(\mathbf{x}) \in [10^{18}, 10^{22}]\,\mathrm{Pa\,s}$ to resolve how lateral variations of 3–4 orders of magnitude in up... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | continental_rifting_breakup_margins | 5 | [
"mechanism"
] | [
"rift",
"lithosphere"
] | [
"crystalline_rock",
"magma_or_melt"
] | [
"crustal_deformation",
"magma_generation_and_ascent"
] | sedimentary_basin_or_continental_margin | Antarctica and the Southern Ocean | multi_million_year_tectonic | Cenozoic | [
"multi-temporal InSAR surface displacement velocity fields and continuous GNSS station networks",
"broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements"
] | [
"inherited structural weakness reactivation and asthenospheric decompression melt partitioning"
] | [
"Buck dike-assisted versus tectonic stretching yield $\\Delta \\sigma_{\\mathrm{magma}} = \\rho_c g z - \\rho_m g z + P_{\\mathrm{ex}} \\le \\sigma_Y(\\varepsilon, \\dot{\\varepsilon})$",
"McKenzie lithospheric thinning factor $\\beta = L / L_0$ and syn-rift isostatic subsidence $S_i(\\beta)$"
] | Formulated in A horizon scan of Antarctic and Southern Ocean science for the next two decades (2015, SCAR-Q51); corroborated across Karagianni et al. (2026) and Han et al. (2025). Remains open due to coupled far-field plate tensional stresses and asthenospheric upwelling buoyancy and pre-existing crustal shear zones, l... | Co-located observations of multi-temporal InSAR surface displacement velocity fields and continuous GNSS station networks and broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements across Antarctica and the Southern Ocean coupled with process-resolving models of crustal defor... | open | regional_resolution_only | OPEN-VERIFIED | true | hard | 4 | 2,015 | M. C. Kennicutt II, S. L. Chown | 2026-10-16T00:00:00 | [
"UEARTH-000351",
"UEARTH-000471",
"UEARTH-000121"
] | [
"10.1017/S0954102014000674",
"10.1029/2025jb032493",
"10.1093/gji/ggaf070",
"10.17226/25761"
] | [
"A horizon scan of Antarctic and Southern Ocean science for the next two decades (2015), Solid Earth Antarctica (SCAR-Q51), DOI:10.1017/S0954102014000674",
"Karagianni et al. (2026), Journal of Geophysical Research Solid Earth, DOI:10.1029/2025jb032493",
"Han et al. (2025), Geophysical Journal International, DO... |
UEARTH-000064 | 64 | Geothermal Heat Flux Distribution Beneath the Antarctic Ice Sheet | What is the spatial magnitude and tectonic control of basal geothermal heat flux beneath the East and West Antarctic Ice Sheets, and where does elevated heat flow trigger basal melting? | What natural processes determine how much heat leaks out of Earth's crust beneath Antarctica's ice sheet and where it melts the base of the ice? | What is the spatial magnitude and tectonic control of basal geothermal heat flux beneath the East and West Antarctic Ice Sheets, and where does elevated heat flow trigger basal melting, specifically constraining basal heat balance $q_G = -k_{\mathrm{crust}} \nabla T_b = \rho_i L_f \dot{m}_b - k_i (\partial T_i / \parti... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | craton_orogen_continental_crust | 5 | [
"mechanism",
"budget"
] | [
"continental_crust",
"orogen"
] | [
"crystalline_rock",
"mantle_silicate"
] | [
"crustal_deformation",
"metamorphic_transformation"
] | tectonic_plate_or_orogen | Antarctica and the Southern Ocean | multi_million_year_tectonic | Cenozoic | [
"multi-spectral/active satellite remote sensing and Doppler radar vertical profile retrievals",
"crustal receiver-function Moho depth maps, Bouguer gravity anomalies, and xenolith thermobarometry"
] | [
"secular continental crust growth versus recycling rates and lower-crustal foundry mechanics"
] | [
"viscous thin-sheet Argand number $\\mathrm{Ar} = g \\rho_c (1 - \\rho_c/\\rho_m) H_c^2 / (\\eta_{\\mathrm{eff}} U_0)$",
"isopycnic cratonic root stability $\\Delta \\rho(T, X_{\\mathrm{Mg\\#}}) = \\rho_0 [ -\\alpha (T - T_0) + \\beta_{\\mathrm{chem}} \\Delta X_{\\mathrm{Mg\\#}} ] \\approx 0$"
] | Formulated in A horizon scan of Antarctic and Southern Ocean science for the next two decades (2015, SCAR-Q52); corroborated across Barbot (2020) and Brink et al. (1993). Remains open due to coupled continental collision, lithospheric thickening, and convective removal of eclogitized lower crust and Moho temperature, c... | Co-located observations of multi-spectral/active satellite remote sensing and Doppler radar vertical profile retrievals and crustal receiver-function Moho depth maps, Bouguer gravity anomalies, and xenolith thermobarometry across Antarctica and the Southern Ocean coupled with process-resolving models of crustal deforma... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,015 | M. C. Kennicutt II, S. L. Chown | 2026-10-16T00:00:00 | [
"UEARTH-000816",
"UEARTH-000264",
"UEARTH-001519"
] | [
"10.1017/S0954102014000674",
"10.1038/s41467-020-18260-8",
"10.1126/science.261.5117.45",
"10.17226/25761"
] | [
"A horizon scan of Antarctic and Southern Ocean science for the next two decades (2015), Solid Earth Antarctica (SCAR-Q52), DOI:10.1017/S0954102014000674",
"Barbot (2020), Nature Communications, DOI:10.1038/s41467-020-18260-8",
"Brink et al. (1993), Science (New York, N.Y.), DOI:10.1126/science.261.5117.45",
... |
UEARTH-000065 | 65 | Cratonic Lithospheric Mantle Root Destruction and Decratonization Mechanics | What physical, chemical, and dynamical mechanisms determine what relative roles do flat-slab hydration metasomatism, asthenospheric thermo-mechanical erosion, and convective Rayleigh-Taylor delamination play in destroying buoyant Archean cratonic keels? | What natural processes determine what destroys the deep, ancient roots of continents that normally survive for billions of years? | How can peridotite xenolith Re-Os depletion ages, FTIR water contents, and S-receiver function LAB depth maps constrain isopycnic condition $\Delta \rho(T, X_{\mathrm{Fe}}) = \rho_0 [\alpha (T - T_0) - \beta_{\mathrm{Fe}} \Delta X_{\mathrm{Fe}}] \approx 0$ and olivine $\mathrm{OH}^-$ hydrolytic weakening to resolve wha... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | craton_orogen_continental_crust | 1 | [
"mechanism",
"reconstruction"
] | [
"continental_crust",
"orogen"
] | [
"crystalline_rock",
"mantle_silicate"
] | [
"crustal_deformation",
"metamorphic_transformation"
] | tectonic_plate_or_orogen | Archean–Proterozoic Cratons and Continental Orogens | multi_million_year_tectonic | Precambrian | [
"broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements",
"crustal receiver-function Moho depth maps, Bouguer gravity anomalies, and xenolith thermobarometry"
] | [
"cratonic lithospheric root stability, metasomatic weakening, and orogenic lower-crustal flow"
] | [
"viscous thin-sheet Argand number $\\mathrm{Ar} = g \\rho_c (1 - \\rho_c/\\rho_m) H_c^2 / (\\eta_{\\mathrm{eff}} U_0)$",
"isopycnic cratonic root stability $\\Delta \\rho(T, X_{\\mathrm{Mg\\#}}) = \\rho_0 [ -\\alpha (T - T_0) + \\beta_{\\mathrm{chem}} \\Delta X_{\\mathrm{Mg\\#}} ] \\approx 0$"
] | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q2d); corroborated across Liu et al. (2023) and Wang et al. (2026). Remains open due to coupled continental collision, lithospheric thickening, and convective removal of eclogitized lower crust and Moho temperature, crustal radiogenic hea... | Co-located observations of broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements and crustal receiver-function Moho depth maps, Bouguer gravity anomalies, and xenolith thermobarometry across Archean–Proterozoic Cratons and Continental Orogens coupled with process-resolving m... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-000056",
"UEARTH-000060",
"UEARTH-000082"
] | [
"10.17226/25761",
"10.1029/2023av001014",
"10.1016/j.earscirev.2026.105713",
"10.17226/25761"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Solid Earth Dynamics (EiT-Q2d), DOI:10.17226/25761",
"Liu et al. (2023), AGU Advances, DOI:10.1029/2023av001014",
"Wang et al. (2026), Earth-Science Reviews, DOI:10.1016/j.earscirev.2026.105713",
"NASEM (2020), A Vision for NSF Earth Sciences 2... |
UEARTH-000066 | 66 | Core-Mantle Electromagnetic, Topographic, and Gravitational Length-of-Day Coupling | What physical, chemical, and dynamical mechanisms determine what relative torque contributions from core-mantle boundary topography, electromagnetic Lorentz coupling, and inner-core gravitational locking drive decadal length-of-day ($\Delta \mathrm{LOD}$) oscillations? | What natural processes determine how forces between Earth's core and mantle slightly speed up or slow down the length of our day over decades? | How can VLBI millisecond length-of-day series and satellite geomagnetic torsional-oscillation inversions constrain axial angular momentum conservation $I_m d\Omega_m / dt = \Gamma_{\mathrm{topo}} + \Gamma_{\mathrm{EM}} + \Gamma_{\mathrm{grav}}$ to resolve what relative torque contributions from core-mantle boundary top... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | core_dynamo_inner_core | 1 | [
"mechanism",
"predictability"
] | [
"inner_core",
"outer_core"
] | [
"core_alloy",
"melt"
] | [
"geomagnetic_dynamo",
"mantle_convection"
] | mantle_or_core_domain | Planetary Deep Interior (Inner and Outer Core) | millennial_to_orbital | Quaternary | [
"PKIKP body-wave travel-time residuals and normal-mode splitting functions",
"satellite and paleomagnetic secular-variation field reconstructions"
] | [
"inner-core crystalline anisotropy, light-element partitioning, and outer-core convective buoyancy flux"
] | [
"magnetic induction $\\partial_t \\mathbf{B} = \\nabla \\times (\\mathbf{u} \\times \\mathbf{B}) + \\eta_m \\nabla^2 \\mathbf{B}$ at $\\mathrm{Ek} \\sim 10^{-15}$ and $\\mathrm{Pm} \\sim 10^{-6}$",
"Elsasser number $\\Lambda = \\sigma B^2 / (\\rho \\Omega) \\sim O(1)$ and thermochemical buoyancy flux $F_B = F_T +... | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q3d); corroborated across Koelemeijer et al. (2012) and Colombi et al. (2014). Remains open due to coupled inner-core crystallization buoyancy flux and secular core cooling and core-mantle boundary topography and heterogeneous lower-mantl... | Co-located observations of PKIKP body-wave travel-time residuals and normal-mode splitting functions and satellite and paleomagnetic secular-variation field reconstructions across Planetary Deep Interior (Inner and Outer Core) coupled with process-resolving models of geomagnetic dynamo to constrain inner-core crystalli... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-000501",
"UEARTH-001245",
"UEARTH-000088"
] | [
"10.17226/25761",
"10.1111/j.1365-246x.2012.05499.x",
"10.1093/gji/ggu112",
"10.17226/25761"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Solid Earth Dynamics (EiT-Q3d), DOI:10.17226/25761",
"Koelemeijer et al. (2012), Geophysical Journal International, DOI:10.1111/j.1365-246x.2012.05499.x",
"Colombi et al. (2014), Geophysical Journal International, DOI:10.1093/gji/ggu112",
"NASE... |
UEARTH-000067 | 67 | Mantle-Wedge Corner Flow Rheology and Anisotropic Viscosity in Subduction Zones | What physical, chemical, and dynamical mechanisms determine how dislocation creep, serpentine foliar anisotropy, and melt-band porosity organize 3D mantle-wedge corner flow and thermal structure beneath volcanic arcs? | What natural processes determine how solid mantle rock flows around the corner above a sinking plate to feed rows of volcanoes? | How can forearc-to-backarc shear-wave splitting arrays, heat-flow transects, and arc-front thermobarometry constrain power-law non-Newtonian Stokes flow $\dot{\varepsilon}_{ij} = A (f_{\mathrm{H2O}})^r \sigma_E^{n-1} \tau_{ij} \exp[-(E^* + PV^*)/(RT)]$ to resolve how dislocation creep, serpentine foliar anisotropy, and... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | subduction_slab_mantle_wedge | 3 | [
"mechanism"
] | [
"subduction_zone",
"upper_mantle"
] | [
"crystalline_rock",
"magma_or_melt"
] | [
"plate_subduction",
"magma_generation_and_ascent"
] | tectonic_plate_or_orogen | Circum-Pacific and Tethyan Subduction Margins | multi_million_year_tectonic | Cenozoic | [
"broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements",
"high-resolution slab-interface seismic attenuation and magnetotelluric conductivity profiles"
] | [
"mechanical coupling and metamorphic dehydration kinetics along the plate interface"
] | [
"composite dislocation-diffusion creep $\\dot{\\varepsilon}_{ij} = (A_{\\mathrm{dis}} \\tau_E^{n-1} + A_{\\mathrm{diff}} d^{-p}) C_{\\mathrm{OH}}^r \\exp[-(E^* + P V^*)/RT] \\tau_{ij}$",
"slab thermal parameter $\\Phi_{\\mathrm{slab}} = t_{\\mathrm{age}} v_{\\mathrm{conv}} \\sin\\theta$ governing dehydration reac... | Formulated in SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022, SZ4D-MDE3); corroborated across Wang et al. (2020) and Han et al. (2025). Remains open due to coupled slab pull, trench rollback, and metamorphic dehydration reactions and slab thermal age, incoming plate hydration state, and overriding-... | Co-located observations of broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements and high-resolution slab-interface seismic attenuation and magnetotelluric conductivity profiles across Circum-Pacific and Tethyan Subduction Margins coupled with process-resolving models of pla... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,022 | E. E. Brodsky, T. A. Plank | 2026-10-16T00:00:00 | [
"UEARTH-000348",
"UEARTH-000057",
"UEARTH-000088"
] | [
"10.25740/hy589fc7561",
"10.1029/2019gc008658",
"10.1093/gji/ggaf070",
"10.17226/25761"
] | [
"SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022), Subduction Geodynamics (SZ4D-MDE3), DOI:10.25740/hy589fc7561",
"Wang et al. (2020), Geochemistry Geophysics Geosystems, DOI:10.1029/2019gc008658",
"Han et al. (2025), Geophysical Journal International, DOI:10.1093/gji/ggaf070",
"NASEM (202... |
UEARTH-000068 | 68 | Lower-Crustal Channel Flow versus Brittle Block Extrusion in Continental Collision | What physical, chemical, and dynamical mechanisms determine whether syn-convergent plateau expansion in large collisional orogens (such as Tibet and the Altiplano) is accommodated primarily by ductile mid-to-lower crustal channel flow or lithospheric strike-slip block extrusion? | What natural processes determine whether giant mountain plateaus spread outward via flowing deep hot crust or sliding rigid fault blocks? | How can magnetotelluric low-resistivity layer continuity, ambient-noise radial anisotropy, and block-bounding fault slip rates constrain Poiseuille-Couette channel flux $q_c = -(h^3 / 12 \eta_{\mathrm{eff}}) (\partial P / \partial x) + U_0 h / 2$ vs. Argand number $\mathrm{Ar}$ to resolve whether syn-convergent plateau... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | craton_orogen_continental_crust | 1 | [
"mechanism"
] | [
"continental_crust",
"orogen"
] | [
"crystalline_rock",
"mantle_silicate"
] | [
"crustal_deformation",
"metamorphic_transformation"
] | tectonic_plate_or_orogen | Himalaya–Tibetan Plateau and Central Asian Orogenic System | multi_million_year_tectonic | Cenozoic | [
"deep magnetotelluric (MT) and electrical resistivity tomography (ERT) conductivity inversions",
"crustal receiver-function Moho depth maps, Bouguer gravity anomalies, and xenolith thermobarometry"
] | [
"secular continental crust growth versus recycling rates and lower-crustal foundry mechanics"
] | [
"viscous thin-sheet Argand number $\\mathrm{Ar} = g \\rho_c (1 - \\rho_c/\\rho_m) H_c^2 / (\\eta_{\\mathrm{eff}} U_0)$",
"isopycnic cratonic root stability $\\Delta \\rho(T, X_{\\mathrm{Mg\\#}}) = \\rho_0 [ -\\alpha (T - T_0) + \\beta_{\\mathrm{chem}} \\Delta X_{\\mathrm{Mg\\#}} ] \\approx 0$"
] | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q5b); corroborated across Li et al. (2026) and Yang et al. (2020). Remains open due to coupled continental collision, lithospheric thickening, and convective removal of eclogitized lower crust and Moho temperature, crustal radiogenic heat... | Co-located observations of deep magnetotelluric (MT) and electrical resistivity tomography (ERT) conductivity inversions and crustal receiver-function Moho depth maps, Bouguer gravity anomalies, and xenolith thermobarometry across Himalaya–Tibetan Plateau and Central Asian Orogenic System coupled with process-resolving... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-000370",
"UEARTH-000498",
"UEARTH-000071"
] | [
"10.17226/25761",
"10.1029/2025gl118727",
"10.1029/2020gl089435",
"10.17226/25761"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Continental Tectonics (EiT-Q5b), DOI:10.17226/25761",
"Li et al. (2026), Geophysical Research Letters, DOI:10.1029/2025gl118727",
"Yang et al. (2020), Geophysical Research Letters, DOI:10.1029/2020gl089435",
"NASEM (2020), A Vision for NSF Eart... |
UEARTH-000069 | 69 | True Polar Wander Rates versus Mantle Convection Planform Reorganization | What physical, chemical, and dynamical mechanisms determine how much of apparent paleomagnetic polar wander over Phanerozoic and Neoproterozoic supercontinent cycles reflects whole-mantle solid-body rotational inertia adjustments (True Polar Wander) versus individual plate motions? | What natural processes determine how fast the entire solid mantle can tip relative to Earth's spin axis when supercontinents break up? | How can global paleomagnetic pole compilations reconciled with hotspot reference frames and tomographic slab remnants constrain Liouville Euler equation $d(\mathbf{I} \cdot \boldsymbol{\omega})/dt + \boldsymbol{\omega} \times (\mathbf{I} \cdot \boldsymbol{\omega}) = 0$ constrained by lower-mantle viscosity $\eta_{\math... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | core_dynamo_inner_core | 1 | [
"mechanism"
] | [
"inner_core",
"outer_core"
] | [
"core_alloy",
"melt"
] | [
"geomagnetic_dynamo",
"mantle_convection"
] | mantle_or_core_domain | Planetary Deep Interior (Inner and Outer Core) | millennial_to_orbital | Precambrian | [
"broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements",
"PKIKP body-wave travel-time residuals and normal-mode splitting functions"
] | [
"core-mantle boundary heat-flux heterogeneity and geomagnetic reversal thresholds"
] | [
"magnetic induction $\\partial_t \\mathbf{B} = \\nabla \\times (\\mathbf{u} \\times \\mathbf{B}) + \\eta_m \\nabla^2 \\mathbf{B}$ at $\\mathrm{Ek} \\sim 10^{-15}$ and $\\mathrm{Pm} \\sim 10^{-6}$",
"Elsasser number $\\Lambda = \\sigma B^2 / (\\rho \\Omega) \\sim O(1)$ and thermochemical buoyancy flux $F_B = F_T +... | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q3e); corroborated across Tackley (2000) and Xie et al. (2025). Remains open due to coupled inner-core crystallization buoyancy flux and secular core cooling and core-mantle boundary topography and heterogeneous lower-mantle thermal condu... | Co-located observations of broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements and PKIKP body-wave travel-time residuals and normal-mode splitting functions across Planetary Deep Interior (Inner and Outer Core) coupled with process-resolving models of geomagnetic dynamo to... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-000054",
"UEARTH-000055",
"UEARTH-000113"
] | [
"10.17226/25761",
"10.1126/science.288.5473.2002",
"10.1038/s41467-025-62711-z",
"10.17226/25761"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Geodynamics (EiT-Q3e), DOI:10.17226/25761",
"Tackley (2000), Science (New York, N.Y.), DOI:10.1126/science.288.5473.2002",
"Xie et al. (2025), Nature communications, DOI:10.1038/s41467-025-62711-z",
"NASEM (2020), A Vision for NSF Earth Science... |
UEARTH-000070 | 70 | Subduction Initiation Mechanics Along Passive Margins Versus Transform/Arc Weaknesses | What physical, chemical, and dynamical mechanisms determine why no Cenozoic passive continental margin has spontaneously collapsed into a self-sustaining subduction zone despite negative buoyancy of old oceanic lithosphere, whereas induced initiation occurs along transform faults and oceanic plateaus? | What natural processes determine how new subduction zones start and why old Atlantic-style coasts haven't begun sinking into the mantle? | How can IODP boninite-forearc basalt stratigraphy (Izu-Bonin-Mariana) and visco-elasto-plastic subduction initiation models constrain integrated lithospheric bending + frictional resistance $F_{\mathrm{resist}} \ge F_{\mathrm{slab\,pull}} = \int g \Delta \rho(z) dz$ to resolve why no Cenozoic passive continental margin... | deep_earth_tectonics_geodynamics_geomagnetism | 1 | Deep Earth, Tectonics, Geodynamics, and Geomagnetism | subduction_slab_mantle_wedge | 3 | [
"mechanism",
"reconstruction"
] | [
"subduction_zone",
"upper_mantle"
] | [
"crystalline_rock",
"magma_or_melt"
] | [
"plate_subduction",
"magma_generation_and_ascent"
] | tectonic_plate_or_orogen | Western Pacific Margin, Marginal Seas, and Subduction Trenches | multi_million_year_tectonic | Cenozoic | [
"high-resolution slab-interface seismic attenuation and magnetotelluric conductivity profiles",
"arc-lava volatile ratios, oxygen fugacity (fO2) oxybarometry, and slab-fluid trace-element signatures"
] | [
"slab-to-wedge volatile and oxidant mass transfer rates and mantle-wedge corner-flow viscosity"
] | [
"composite dislocation-diffusion creep $\\dot{\\varepsilon}_{ij} = (A_{\\mathrm{dis}} \\tau_E^{n-1} + A_{\\mathrm{diff}} d^{-p}) C_{\\mathrm{OH}}^r \\exp[-(E^* + P V^*)/RT] \\tau_{ij}$",
"slab thermal parameter $\\Phi_{\\mathrm{slab}} = t_{\\mathrm{age}} v_{\\mathrm{conv}} \\sin\\theta$ governing dehydration reac... | Formulated in Exploring Earth by Scientific Ocean Drilling: 2050 Science Framework (2020, IODP-SO2d); corroborated across Liu et al. (2025) and Lévy et al. (2012). Remains open due to coupled slab pull, trench rollback, and metamorphic dehydration reactions and slab thermal age, incoming plate hydration state, and over... | Co-located observations of high-resolution slab-interface seismic attenuation and magnetotelluric conductivity profiles and arc-lava volatile ratios, oxygen fugacity (fO2) oxybarometry, and slab-fluid trace-element signatures across Western Pacific Margin, Marginal Seas, and Subduction Trenches coupled with process-res... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,020 | A. A. P. Koppers, R. Coggon | 2026-10-16T00:00:00 | [
"UEARTH-000062",
"UEARTH-000978",
"UEARTH-000083"
] | [
"10.6075/J0W66J9H",
"10.1016/j.epsl.2025.119765",
"10.1111/j.1365-246x.2011.05303.x",
"10.17226/25761"
] | [
"Exploring Earth by Scientific Ocean Drilling: 2050 Science Framework (2020), Oceanic Lithosphere (IODP-SO2d), DOI:10.6075/J0W66J9H",
"Liu et al. (2025), Earth and Planetary Science Letters, DOI:10.1016/j.epsl.2025.119765",
"Lévy et al. (2012), Geophysical Journal International, DOI:10.1111/j.1365-246x.2011.053... |
UEARTH-000071 | 71 | Precursory Aseismic Slow Slip Versus Cascade Triggering Before Megathrust Earthquakes | What physical, chemical, and dynamical mechanisms determine whether large megathrust earthquakes nucleate through a deterministic runaway expansion of a slow-slip patch (preslip model) or through stochastic stress-transfer cascades of smaller foreshocks? | What natural processes determine whether giant earthquakes start with a slow silent slip event or a chain reaction of smaller foreshocks? | How can near-trench seafloor borehole strainmeters, ocean-bottom pressure gauges, and repeating earthquake catalogs constrain critical nucleation length $L_c = \mu D_c / [(b - a) \sigma_n']$ in rate-and-state friction $\tau = \sigma_n' [\mu_0 + a \ln(V/V_0) + b \ln(V_0 \theta / D_c)]$ to resolve whether large megathrus... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | slow_slip_tremor_megathrust | 3 | [
"mechanism"
] | [
"subduction_zone",
"fault_zone"
] | [
"crystalline_rock",
"hydrothermal_fluid"
] | [
"fault_rupture_and_slip",
"plate_subduction"
] | fault_or_volcanic_edifice | Subduction Megathrust Interfaces | synoptic_to_seasonal | Anthropocene | [
"seafloor borehole pressure gauges, continuous GNSS networks, and tectonic tremor catalogs",
"seismic Vp/Vs ratios and magnetotelluric images of overpressured plate-interface fluids"
] | [
"stress transfer from episodic tremor and slow slip (ETS) to locked megathrust asperities"
] | [
"effective normal stress $\\sigma_n' = \\sigma_n - \\alpha_B P_f$ under near-lithostatic pore-fluid factor $\\lambda_f = P_f / \\sigma_v \\to 1$",
"slow-slip moment-duration scaling $M_0 = \\mu \\bar{D} A \\propto T^\\alpha$ across velocity-transition regimes"
] | Formulated in SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022, SZ4D-FEC1); corroborated across Bekaert et al. (2015) and Magen et al. (2024). Remains open due to coupled subduction convergence loading and metamorphic fluid release along the downdip interface and interface temperature profile, subduc... | Co-located observations of seafloor borehole pressure gauges, continuous GNSS networks, and tectonic tremor catalogs and seismic Vp/Vs ratios and magnetotelluric images of overpressured plate-interface fluids across Subduction Megathrust Interfaces coupled with process-resolving models of fault rupture and slip to cons... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,022 | E. E. Brodsky, T. A. Plank | 2026-10-16T00:00:00 | [
"UEARTH-000075",
"UEARTH-000072",
"UEARTH-000068"
] | [
"10.25740/hy589fc7561",
"10.1002/2014jb011557",
"10.1029/2024jb028903",
"10.25740/hy589fc7561"
] | [
"SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022), Faulting and Earthquake Cycles (SZ4D-FEC1), DOI:10.25740/hy589fc7561",
"Bekaert et al. (2015), Journal of Geophysical Research Solid Earth, DOI:10.1002/2014jb011557",
"Magen et al. (2024), Journal of Geophysical Research Solid Earth, DOI:10.... |
UEARTH-000072 | 72 | Fault-Valve Permeability Evolution and Fluid-Pressure Cycling in Episodic Tremor and Slow Slip | What physical, chemical, and dynamical mechanisms determine how silica/carbonate precipitation healing and slip-induced dilatancy regulate cyclic pore-fluid overpressure ($\lambda_f = P_f / \sigma_v \to 1$) in the deep subduction tremor and slow-slip zone? | What natural processes determine how trapped high-pressure water deep on subduction faults opens and seals cracks to cause rhythmic slow earthquakes? | How can 4D time-lapse seismic $V_P/V_S$ tomography, shear-wave splitting transients, and exhumed subduction melange veins constrain coupled pore-pressure diffusion $\partial P_f / \partial t = \nabla \cdot [(k / \eta_f \beta_s) \nabla P_f] - (\Delta \phi_{\mathrm{dil}} / \beta_s) \dot{\gamma} + \dot{\Gamma}_{\mathrm{de... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | slow_slip_tremor_megathrust | 3 | [
"mechanism"
] | [
"subduction_zone",
"fault_zone"
] | [
"crystalline_rock",
"hydrothermal_fluid"
] | [
"fault_rupture_and_slip",
"plate_subduction"
] | fault_or_volcanic_edifice | Subduction Megathrust Interfaces | synoptic_to_seasonal | Holocene | [
"broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements",
"seafloor borehole pressure gauges, continuous GNSS networks, and tectonic tremor catalogs"
] | [
"effective normal stress and fault-valve permeability evolution across the brittle-ductile transition"
] | [
"effective normal stress $\\sigma_n' = \\sigma_n - \\alpha_B P_f$ under near-lithostatic pore-fluid factor $\\lambda_f = P_f / \\sigma_v \\to 1$",
"slow-slip moment-duration scaling $M_0 = \\mu \\bar{D} A \\propto T^\\alpha$ across velocity-transition regimes"
] | Formulated in SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022, SZ4D-FEC3); corroborated across Li et al. (2016) and Costantino et al. (2026). Remains open due to coupled subduction convergence loading and metamorphic fluid release along the downdip interface and interface temperature profile, subduc... | Co-located observations of broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements and seafloor borehole pressure gauges, continuous GNSS networks, and tectonic tremor catalogs across Subduction Megathrust Interfaces coupled with process-resolving models of fault rupture and s... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,022 | E. E. Brodsky, T. A. Plank | 2026-10-16T00:00:00 | [
"UEARTH-001511",
"UEARTH-002454",
"UEARTH-000070"
] | [
"10.25740/hy589fc7561",
"10.1002/2016jb012857",
"10.1029/2025gl117446",
"10.25740/hy589fc7561"
] | [
"SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022), Faulting and Earthquake Cycles (SZ4D-FEC3), DOI:10.25740/hy589fc7561",
"Li et al. (2016), Journal of Geophysical Research Solid Earth, DOI:10.1002/2016jb012857",
"Costantino et al. (2026), Geophysical Research Letters, DOI:10.1029/2025gl1174... |
UEARTH-000073 | 73 | Earthquake Fracture Energy Partitioning Between Frictional Heat and Off-Fault Rock Damage | What physical, chemical, and dynamical mechanisms determine what fraction of the total coseismic breakdown work ($G_c$) in crustal and megathrust earthquakes is dissipated as off-fault inelastic rock pulverization versus on-fault frictional heating and flash melting? | What natural processes determine how much of an earthquake's energy goes into shattering surrounding rock versus heating the fault plane? | How can borehole fault-zone temperature anomalies (JFAST/Wenchuan), pulverization damage-zone mapping, and high-velocity rotary shear constrain energy budget $\Delta W = E_R + G_f + E_{\mathrm{heat}}$ with breakdown work $G_f = \int_0^{\delta_c} [\tau(\delta) - \tau_d] d\delta$ to resolve what fraction of the total cos... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | earthquake_rupture_fault_mechanics | 3 | [
"mechanism",
"budget"
] | [
"fault_zone",
"continental_crust"
] | [
"crystalline_rock",
"pore_water"
] | [
"fault_rupture_and_slip",
"crustal_deformation"
] | fault_or_volcanic_edifice | Plate-Boundary and Intraplate Seismogenic Fault Zones | instantaneous_to_event | Anthropocene | [
"near-field broadband seismograms, high-rate GNSS displacements, and InSAR coseismic interferograms",
"fault-zone drilling core microstructure and laboratory rotary-shear friction velocity dependence"
] | [
"partitioning between seismic radiation, fracture energy, and off-fault plastic damage"
] | [
"rate-and-state friction $\\tau = \\sigma_n' [\\mu_0 + a \\ln(V/V_0) + b \\ln(V_0 \\theta / D_c)]$ with thermal pressurization $\\partial_t P_f = \\Lambda_{\\mathrm{TP}} \\tau V / w + D_{\\mathrm{hyd}} \\partial_{yy} P_f$",
"elastodynamic fracture energy balance $G_c = \\int_0^{D_c} (\\tau(u) - \\tau_r) du$ and c... | Formulated in SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022, SZ4D-FEC4); corroborated across Cocco et al. (2023) and Rempe et al. (2018). Remains partially solved due to coupled tectonic shear-stress loading and coseismic dynamic pore-pressure transients and fault-zone geometric complexity, gouge ... | Co-located observations of near-field broadband seismograms, high-rate GNSS displacements, and InSAR coseismic interferograms and fault-zone drilling core microstructure and laboratory rotary-shear friction velocity dependence across Plate-Boundary and Intraplate Seismogenic Fault Zones coupled with process-resolving m... | partially_solved | mechanism_known_magnitude_uncertain | PARTIAL-PROGRESS | true | hard | 4 | 2,022 | E. E. Brodsky, T. A. Plank | 2026-10-16T00:00:00 | [
"UEARTH-000085",
"UEARTH-001543",
"UEARTH-000135"
] | [
"10.25740/hy589fc7561",
"10.1146/annurev-earth-071822-100304",
"10.1029/2018jb015900",
"10.25740/hy589fc7561"
] | [
"SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022), Faulting and Earthquake Cycles (SZ4D-FEC4), DOI:10.25740/hy589fc7561",
"Cocco et al. (2023), Annual Review of Earth and Planetary Sciences, DOI:10.1146/annurev-earth-071822-100304",
"Rempe et al. (2018), Journal of Geophysical Research Solid... |
UEARTH-000074 | 74 | Supershear Rupture Transition Conditions on Strike-Slip and Subduction Faults | What physical, chemical, and dynamical mechanisms determine what fault-geometry smoothness, bimaterial elastic contrast, and pre-stress level $(\tau_0 - \tau_r)/(\tau_p - \tau_r)$ allow earthquake ruptures to jump the forbidden Rayleigh-Eshelby speed gap and propagate at supershear velocities ($v_r \ge \sqrt{2} c_S$)? | What natural processes determine what causes certain earthquakes to break the shear-wave 'sound barrier' and produce destructive shock waves? | How can near-fault high-rate GNSS, strong-motion Mach-cone waveforms, and optical/SAR sub-pixel fault offset profiles constrain Burridge-Andrews dimensionless seismic $S$-ratio $S = (\tau_p - \tau_0)/(\tau_0 - \tau_f) \le 1.77$ in elastodynamic fracture to resolve what fault-geometry smoothness, bimaterial elastic cont... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | earthquake_rupture_fault_mechanics | 1 | [
"mechanism",
"hazard_generation"
] | [
"fault_zone",
"continental_crust"
] | [
"crystalline_rock",
"pore_water"
] | [
"fault_rupture_and_slip",
"crustal_deformation"
] | fault_or_volcanic_edifice | Plate-Boundary and Intraplate Seismogenic Fault Zones | instantaneous_to_event | Holocene | [
"multi-temporal InSAR surface displacement velocity fields and continuous GNSS station networks",
"near-field broadband seismograms, high-rate GNSS displacements, and InSAR coseismic interferograms"
] | [
"rate-and-state frictional healing, dynamic pore-fluid pressurization, and rupture arrest thresholds"
] | [
"rate-and-state friction $\\tau = \\sigma_n' [\\mu_0 + a \\ln(V/V_0) + b \\ln(V_0 \\theta / D_c)]$ with thermal pressurization $\\partial_t P_f = \\Lambda_{\\mathrm{TP}} \\tau V / w + D_{\\mathrm{hyd}} \\partial_{yy} P_f$",
"elastodynamic fracture energy balance $G_c = \\int_0^{D_c} (\\tau(u) - \\tau_r) du$ and c... | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q4b); corroborated across Jara et al. (2021) and Wang et al. (2017). Remains open due to coupled tectonic shear-stress loading and coseismic dynamic pore-pressure transients and fault-zone geometric complexity, gouge mineralogy, and depth... | Co-located observations of multi-temporal InSAR surface displacement velocity fields and continuous GNSS station networks and near-field broadband seismograms, high-rate GNSS displacements, and InSAR coseismic interferograms across Plate-Boundary and Intraplate Seismogenic Fault Zones coupled with process-resolving mod... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-001499",
"UEARTH-000083",
"UEARTH-000062"
] | [
"10.17226/25761",
"10.1098/rspa.2021.0364",
"10.1016/j.epsl.2017.10.056",
"10.25740/hy589fc7561"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Priority Questions (EiT-Q4b), DOI:10.17226/25761",
"Jara et al. (2021), Proceedings. Mathematical, physical, and engineering sciences, DOI:10.1098/rspa.2021.0364",
"Wang et al. (2017), Earth and Planetary Science Letters, DOI:10.1016/j.epsl.2017.... |
UEARTH-000075 | 75 | Moment-Duration Scaling Laws Connecting Slow Slip Events and Regular Earthquakes | What physical, chemical, and dynamical mechanisms determine why slow slip events and tectonic tremor appear to follow a linear moment-duration scaling ($M_0 \propto T$) whereas regular fast earthquakes follow cubic scaling ($M_0 \propto T^3$), or whether slow slip comprises self-similar sub-events obeying a unified sca... | What natural processes determine why slow earthquakes seem to grow in size proportionally to their duration while regular earthquakes grow with the cube of duration? | How can broadband geodetic-seismic slow-slip inversions and low-frequency earthquake (LFE) template-matched catalogs constrain seismic moment scaling $M_0 = \mu \bar{D} A \propto T^{\alpha}$ with exponent transition $\alpha \in [1, 3]$ across rupture speeds $v_r$ to resolve why slow slip events and tectonic tremor appe... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | slow_slip_tremor_megathrust | 3 | [
"mechanism"
] | [
"subduction_zone",
"fault_zone"
] | [
"crystalline_rock",
"hydrothermal_fluid"
] | [
"fault_rupture_and_slip",
"plate_subduction"
] | fault_or_volcanic_edifice | Subduction Megathrust Interfaces | synoptic_to_seasonal | Anthropocene | [
"seafloor borehole pressure gauges, continuous GNSS networks, and tectonic tremor catalogs",
"seismic Vp/Vs ratios and magnetotelluric images of overpressured plate-interface fluids"
] | [
"stress transfer from episodic tremor and slow slip (ETS) to locked megathrust asperities"
] | [
"effective normal stress $\\sigma_n' = \\sigma_n - \\alpha_B P_f$ under near-lithostatic pore-fluid factor $\\lambda_f = P_f / \\sigma_v \\to 1$",
"slow-slip moment-duration scaling $M_0 = \\mu \\bar{D} A \\propto T^\\alpha$ across velocity-transition regimes"
] | Formulated in The geophysics, geology and mechanics of slow fault slip (2018, Burgmann-S4); corroborated across Hu et al. (2023) and Michel et al. (2018). Remains open due to coupled subduction convergence loading and metamorphic fluid release along the downdip interface and interface temperature profile, subducted sed... | Co-located observations of seafloor borehole pressure gauges, continuous GNSS networks, and tectonic tremor catalogs and seismic Vp/Vs ratios and magnetotelluric images of overpressured plate-interface fluids across Subduction Megathrust Interfaces coupled with process-resolving models of fault rupture and slip to cons... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,018 | Roland Bürgmann | 2026-10-16T00:00:00 | [
"UEARTH-002262",
"UEARTH-000071",
"UEARTH-000070"
] | [
"10.1016/j.epsl.2018.04.062",
"10.1073/pnas.2305134120",
"10.1007/s00024-018-1991-x",
"10.25740/hy589fc7561"
] | [
"The geophysics, geology and mechanics of slow fault slip (2018), Slow Fault Slip (Burgmann-S4), DOI:10.1016/j.epsl.2018.04.062",
"Hu et al. (2023), Proceedings of the National Academy of Sciences, DOI:10.1073/pnas.2305134120",
"Michel et al. (2018), Pure and Applied Geophysics, DOI:10.1007/s00024-018-1991-x",
... |
UEARTH-000076 | 76 | Conduit Ascent Controls on Effusive-to-Explosive Transitions in Silicic Eruptions | What physical, chemical, and dynamical mechanisms determine what competition among magma ascent decompression rate, bubble coalescence outgassing through permeable shear bands, and microlite crystallization viscosity jump controls whether a silicic eruption is effusive (lava dome) or Plinian explosive? | What natural processes determine what determines whether sticky volcanic magma oozes out gently as a lava dome or explodes violently into an ash column? | How can experimental decompression vesiculation, pyroclast micro-CT permeability tomography, and infrasound/tilt eruption monitoring constrain Deborah number $\mathrm{De} = \eta \dot{\gamma} / G_{\infty} \ge 10^{-2}$ and Peclet outgassing number $\mathrm{Pe}_{\mathrm{gas}} = v_{\mathrm{ascent}} R_c^2 \eta_g / (k_{\math... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | volcanic_plumbing_eruption_degassing | 3 | [
"mechanism",
"hazard_generation"
] | [
"magma_reservoir",
"continental_crust"
] | [
"magma_or_melt",
"hydrothermal_fluid"
] | [
"volcanic_degassing_and_eruption",
"magma_generation_and_ascent"
] | fault_or_volcanic_edifice | Active Arc, Rift, and Hotspot Volcanic Systems | instantaneous_to_event | Holocene | [
"broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements",
"edifice tilt/InSAR deformation, volcano-tectonic seismicity, and UV/FTIR SO2/CO2 gas plume ratios"
] | [
"crystal-mush remobilization timescales, conduit magma ascent rates, and effusive-to-explosive transitions"
] | [
"multiphase magma viscosity $\\eta(\\phi_c, C_{\\mathrm{H2O}}, T) = \\eta_{\\mathrm{melt}}(C_{\\mathrm{H2O}}, T) (1 - \\phi_c / \\phi_m)^{-B \\phi_m}$ and Deborah fragmentation criterion $\\mathrm{De} = \\eta \\dot{\\gamma} / G_\\infty \\ge 10^{-2}$",
"conduit momentum-continuity balance $\\rho_m u \\partial_z u ... | Formulated in Volcanic Eruptions and Their Repose, Unrest, Precursors, and Timing (ERUPT) (2017, ERUPT-GC2); corroborated across Research Group et al. (2018) and Hotta et al. (2025). Remains open due to coupled mafic magma recharge, volatile exsolution buoyancy, and conduit shear heating and magma viscosity, conduit ge... | Co-located observations of broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements and edifice tilt/InSAR deformation, volcano-tectonic seismicity, and UV/FTIR SO2/CO2 gas plume ratios across Active Arc, Rift, and Hotspot Volcanic Systems coupled with process-resolving models ... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,017 | Committee on Improving Understanding of Volcanic Eruptions, M. Manga (Chair) | 2026-10-16T00:00:00 | [
"UEARTH-001601",
"UEARTH-001526",
"UEARTH-000345"
] | [
"10.17226/24650",
"10.1038/s41598-018-22539-8",
"10.1029/2024jb030966",
"10.25740/hy589fc7561"
] | [
"Volcanic Eruptions and Their Repose, Unrest, Precursors, and Timing (ERUPT) (2017), Volcano Grand Challenges (ERUPT-GC2), DOI:10.17226/24650",
"Research Group et al. (2018), Scientific reports, DOI:10.1038/s41598-018-22539-8",
"Hotta et al. (2025), Journal of Geophysical Research Solid Earth, DOI:10.1029/2024j... |
UEARTH-000077 | 77 | Excess Sulfur Degassing Paradox and Vapor-Phase Partitioning in Arc Volcanoes | What physical, chemical, and dynamical mechanisms determine why satellite-measured syn-eruptive $\mathrm{SO}_2$ gas emissions frequently exceed the sulfur mass dissolved in the erupted silicate melt volume by factors of $10\text{--}100$, and how pre-eruptive supercritical vapor phases accumulate at the top of magma res... | What natural processes determine why volcanoes release far more sulfur gas during eruptions than could have been dissolved in the erupted lava? | How can TROPOMI/OMI satellite $\mathrm{SO}_2$ retrievals paired with unhomogenized melt-inclusion and apatite volatile analyses constrain fluid-melt sulfur partition coefficient $D_{\mathrm{S}}^{\mathrm{fluid/melt}}(P, T, f\mathrm{O}_2, X_{\mathrm{FeO}})$ and anhydrite/pyrrhotite stability to resolve why satellite-meas... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | volcanic_plumbing_eruption_degassing | 3 | [
"mechanism",
"budget"
] | [
"magma_reservoir",
"continental_crust"
] | [
"magma_or_melt",
"hydrothermal_fluid"
] | [
"volcanic_degassing_and_eruption",
"magma_generation_and_ascent"
] | fault_or_volcanic_edifice | Active Arc, Rift, and Hotspot Volcanic Systems | instantaneous_to_event | Anthropocene | [
"multi-spectral/active satellite remote sensing and Doppler radar vertical profile retrievals",
"edifice tilt/InSAR deformation, volcano-tectonic seismicity, and UV/FTIR SO2/CO2 gas plume ratios"
] | [
"volatile exsolution kinetics and overpressure thresholds triggering dike propagation"
] | [
"multiphase magma viscosity $\\eta(\\phi_c, C_{\\mathrm{H2O}}, T) = \\eta_{\\mathrm{melt}}(C_{\\mathrm{H2O}}, T) (1 - \\phi_c / \\phi_m)^{-B \\phi_m}$ and Deborah fragmentation criterion $\\mathrm{De} = \\eta \\dot{\\gamma} / G_\\infty \\ge 10^{-2}$",
"conduit momentum-continuity balance $\\rho_m u \\partial_z u ... | Formulated in Volcanic Eruptions and Their Repose, Unrest, Precursors, and Timing (ERUPT) (2017, ERUPT-GC3); corroborated across Zhao et al. (2024) and Males et al. (2021). Remains open due to coupled mafic magma recharge, volatile exsolution buoyancy, and conduit shear heating and magma viscosity, conduit geometry, an... | Co-located observations of multi-spectral/active satellite remote sensing and Doppler radar vertical profile retrievals and edifice tilt/InSAR deformation, volcano-tectonic seismicity, and UV/FTIR SO2/CO2 gas plume ratios across Active Arc, Rift, and Hotspot Volcanic Systems coupled with process-resolving models of vol... | open | mechanism_known_magnitude_uncertain | OPEN-VERIFIED | true | hard | 4 | 2,017 | Committee on Improving Understanding of Volcanic Eruptions, M. Manga (Chair) | 2026-10-16T00:00:00 | [
"UEARTH-000078",
"UEARTH-002159",
"UEARTH-000054"
] | [
"10.17226/24650",
"10.1016/j.gca.2024.03.030",
"10.3389/feart.2021.750063",
"10.25740/hy589fc7561"
] | [
"Volcanic Eruptions and Their Repose, Unrest, Precursors, and Timing (ERUPT) (2017), Volcano Grand Challenges (ERUPT-GC3), DOI:10.17226/24650",
"Zhao et al. (2024), Geochimica et Cosmochimica Acta, DOI:10.1016/j.gca.2024.03.030",
"Males et al. (2021), Frontiers in Earth Science, DOI:10.3389/feart.2021.750063",
... |
UEARTH-000078 | 78 | Volatile Budget Control on Arc Magma Storage Depth in the Crust | What physical, chemical, and dynamical mechanisms determine whether the clustering of arc magma storage reservoirs at $4\text{--}10\,\mathrm{km}$ depth globally is controlled primarily by $\mathrm{H}_2\mathrm{O}$-saturation degassing viscosity lockup ('viscous death') or neutral crustal density buoyancy? | What natural processes determine why magma chambers beneath arc volcanoes around the world almost always stall between 4 and 10 kilometers deep? | How can plagioclase/amphibole hygrometry, melt-inclusion $\mathrm{H}_2\mathrm{O}\text{--}\mathrm{CO}_2$ saturation pressures, and seismic magma-body imaging constrain $\mathrm{H}_2\mathrm{O}$ solubility $C_{\mathrm{H2O}}^{\mathrm{sat}}(P) \propto P^{0.5}$ inducing a $10^3\text{--}10^5\times$ viscosity jump $\eta(C_{\ma... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | volcanic_plumbing_eruption_degassing | 3 | [
"mechanism",
"budget"
] | [
"magma_reservoir",
"continental_crust"
] | [
"magma_or_melt",
"hydrothermal_fluid"
] | [
"volcanic_degassing_and_eruption",
"magma_generation_and_ascent"
] | fault_or_volcanic_edifice | Active Arc, Rift, and Hotspot Volcanic Systems | instantaneous_to_event | Holocene | [
"edifice tilt/InSAR deformation, volcano-tectonic seismicity, and UV/FTIR SO2/CO2 gas plume ratios",
"melt-inclusion volatile contents and crystal-cargo diffusion chronometry"
] | [
"crystal-mush remobilization timescales, conduit magma ascent rates, and effusive-to-explosive transitions"
] | [
"multiphase magma viscosity $\\eta(\\phi_c, C_{\\mathrm{H2O}}, T) = \\eta_{\\mathrm{melt}}(C_{\\mathrm{H2O}}, T) (1 - \\phi_c / \\phi_m)^{-B \\phi_m}$ and Deborah fragmentation criterion $\\mathrm{De} = \\eta \\dot{\\gamma} / G_\\infty \\ge 10^{-2}$",
"conduit momentum-continuity balance $\\rho_m u \\partial_z u ... | Formulated in SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022, SZ4D-MDE1); corroborated across Ranta et al. (2023) and Dai et al. (2026). Remains open due to coupled mafic magma recharge, volatile exsolution buoyancy, and conduit shear heating and magma viscosity, conduit geometry, and edifice stres... | Co-located observations of edifice tilt/InSAR deformation, volcano-tectonic seismicity, and UV/FTIR SO2/CO2 gas plume ratios and melt-inclusion volatile contents and crystal-cargo diffusion chronometry across Active Arc, Rift, and Hotspot Volcanic Systems coupled with process-resolving models of volcanic degassing and ... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,022 | E. E. Brodsky, T. A. Plank | 2026-10-16T00:00:00 | [
"UEARTH-000077",
"UEARTH-001526",
"UEARTH-000351"
] | [
"10.25740/hy589fc7561",
"10.1016/j.jvolgeores.2023.107776",
"10.1029/2025gl117016",
"10.25740/hy589fc7561"
] | [
"SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022), Magmatic Drivers (SZ4D-MDE1), DOI:10.25740/hy589fc7561",
"Ranta et al. (2023), Journal of Volcanology and Geothermal Research, DOI:10.1016/j.jvolgeores.2023.107776",
"Dai et al. (2026), Geophysical Research Letters, DOI:10.1029/2025gl117016"... |
UEARTH-000079 | 79 | Coupling Between Subduction Megathrust Earthquakes and Arc Volcanic Eruptions | What physical, chemical, and dynamical mechanisms govern by what static dilatation, dynamic seismic wave-induced bubble nucleation, or crustal hydrothermal permeability enhancement do great subduction earthquakes ($M_w \ge 8.0$) modulate volcanic unrest and eruption rates along the adjacent volcanic arc? | What natural processes determine how giant subduction earthquakes trigger or suppress volcanic eruptions in the nearby mountain chain? | How can centennial global earthquake-eruption space-time catalogs and post-megathrust InSAR volcano deformation time series constrain volumetric strain change $\Delta \varepsilon_{kk} = \Delta \sigma_{kk} / (3K)$ and rectified bubble diffusion under dynamic pressure oscillations to resolve by what static dilatation, dy... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | volcanic_plumbing_eruption_degassing | 3 | [
"mechanism",
"feedback"
] | [
"magma_reservoir",
"continental_crust"
] | [
"magma_or_melt",
"hydrothermal_fluid"
] | [
"volcanic_degassing_and_eruption",
"magma_generation_and_ascent"
] | fault_or_volcanic_edifice | Active Arc, Rift, and Hotspot Volcanic Systems | instantaneous_to_event | Anthropocene | [
"multi-temporal InSAR surface displacement velocity fields and continuous GNSS station networks",
"edifice tilt/InSAR deformation, volcano-tectonic seismicity, and UV/FTIR SO2/CO2 gas plume ratios"
] | [
"volatile exsolution kinetics and overpressure thresholds triggering dike propagation"
] | [
"multiphase magma viscosity $\\eta(\\phi_c, C_{\\mathrm{H2O}}, T) = \\eta_{\\mathrm{melt}}(C_{\\mathrm{H2O}}, T) (1 - \\phi_c / \\phi_m)^{-B \\phi_m}$ and Deborah fragmentation criterion $\\mathrm{De} = \\eta \\dot{\\gamma} / G_\\infty \\ge 10^{-2}$",
"conduit momentum-continuity balance $\\rho_m u \\partial_z u ... | Formulated in SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022, SZ4D-MDE2); corroborated across Jones et al. (2019) and Wang et al. (2024). Remains open due to coupled mafic magma recharge, volatile exsolution buoyancy, and conduit shear heating and magma viscosity, conduit geometry, and edifice stre... | Co-located observations of multi-temporal InSAR surface displacement velocity fields and continuous GNSS station networks and edifice tilt/InSAR deformation, volcano-tectonic seismicity, and UV/FTIR SO2/CO2 gas plume ratios across Active Arc, Rift, and Hotspot Volcanic Systems coupled with process-resolving models of v... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,022 | E. E. Brodsky, T. A. Plank | 2026-10-16T00:00:00 | [
"UEARTH-001601",
"UEARTH-000076",
"UEARTH-000070"
] | [
"10.25740/hy589fc7561",
"10.1038/s41467-019-11750-4",
"10.1029/2023jb028280",
"10.25740/hy589fc7561"
] | [
"SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022), Magmatic Drivers (SZ4D-MDE2), DOI:10.25740/hy589fc7561",
"Jones et al. (2019), Nature communications, DOI:10.1038/s41467-019-11750-4",
"Wang et al. (2024), Journal of Geophysical Research Solid Earth, DOI:10.1029/2023jb028280",
"E. E. Brod... |
UEARTH-000080 | 80 | Caldera Ring-Fault Roof Collapse Mechanics and Supereruption Initiation | What physical, chemical, and dynamical mechanisms determine what roof aspect ratio ($h_{\mathrm{roof}} / D_{\mathrm{chamber}}$), magma chamber underpressure ($\Delta P_{\mathrm{crit}}$), and ring-fault dike lubrication govern the transition from central-vent Plinian eruption to catastrophic caldera-forming roof collaps... | What natural processes determine what triggers the roof of a giant magma chamber to collapse inward during a supereruption? | How can analog/DEM caldera collapse modeling, piston-subsidence seismic very-long-period (VLP) signals (Kīlauea/Bárðarbunga), and ignimbrite stratigraphy constrain dimensionless chamber underpressure $\Delta P^* = \Delta P (D / h_{\mathrm{roof}})^2 / \sigma_Y$ and piston-subsidence friction balance to resolve what roof... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | volcanic_plumbing_eruption_degassing | 3 | [
"mechanism",
"threshold"
] | [
"magma_reservoir",
"continental_crust"
] | [
"magma_or_melt",
"hydrothermal_fluid"
] | [
"volcanic_degassing_and_eruption",
"magma_generation_and_ascent"
] | fault_or_volcanic_edifice | Active Arc, Rift, and Hotspot Volcanic Systems | instantaneous_to_event | Holocene | [
"edifice tilt/InSAR deformation, volcano-tectonic seismicity, and UV/FTIR SO2/CO2 gas plume ratios",
"melt-inclusion volatile contents and crystal-cargo diffusion chronometry"
] | [
"crystal-mush remobilization timescales, conduit magma ascent rates, and effusive-to-explosive transitions"
] | [
"multiphase magma viscosity $\\eta(\\phi_c, C_{\\mathrm{H2O}}, T) = \\eta_{\\mathrm{melt}}(C_{\\mathrm{H2O}}, T) (1 - \\phi_c / \\phi_m)^{-B \\phi_m}$ and Deborah fragmentation criterion $\\mathrm{De} = \\eta \\dot{\\gamma} / G_\\infty \\ge 10^{-2}$",
"conduit momentum-continuity balance $\\rho_m u \\partial_z u ... | Formulated in Volcanic Eruptions and Their Repose, Unrest, Precursors, and Timing (ERUPT) (2017, ERUPT-GC4); corroborated across Aellig et al. (2026) and Mourey et al. (2025). Remains open due to coupled mafic magma recharge, volatile exsolution buoyancy, and conduit shear heating and magma viscosity, conduit geometry,... | Co-located observations of edifice tilt/InSAR deformation, volcano-tectonic seismicity, and UV/FTIR SO2/CO2 gas plume ratios and melt-inclusion volatile contents and crystal-cargo diffusion chronometry across Active Arc, Rift, and Hotspot Volcanic Systems coupled with process-resolving models of volcanic degassing and ... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,017 | Committee on Improving Understanding of Volcanic Eruptions, M. Manga (Chair) | 2026-10-16T00:00:00 | [
"UEARTH-000076",
"UEARTH-000077",
"UEARTH-000307"
] | [
"10.17226/24650",
"10.1029/2026jb034434",
"10.1007/s00410-025-02204-w",
"10.25740/hy589fc7561"
] | [
"Volcanic Eruptions and Their Repose, Unrest, Precursors, and Timing (ERUPT) (2017), Volcano Grand Challenges (ERUPT-GC4), DOI:10.17226/24650",
"Aellig et al. (2026), Journal of Geophysical Research Solid Earth, DOI:10.1029/2026jb034434",
"Mourey et al. (2025), Contributions to Mineralogy and Petrology, DOI:10.... |
UEARTH-000081 | 81 | Shear-Zone Liquefaction and Runout Hyper-Mobility of Coseismic and Rainfall Landslides | What physical, chemical, and dynamical mechanisms determine what coupled grain-crushing comminution, undrained pore-pressure generation, and acoustic/thermal fluidization reduce the apparent basal friction coefficient ($\mu_{\mathrm{app}} = H / L \ll 0.2$) of large rock avalanches and debris flows? | What natural processes determine why giant landslides and debris flows travel miles across nearly flat ground as if riding on a frictionless cushion? | How can high-speed ring-shear apparatus tests, broadband landslide seismology force-history inversions, and LiDAR deposit differencing constrain Iverson pore-pressure diffusion number $N_{\mathrm{diff}} = (D_{\mathrm{hyd}} t_{\mathrm{runout}}) / h^2$ and Savage-Hutter granular stress scaling to resolve what coupled gra... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | landslide_debris_flow_mass_wasting | 3 | [
"mechanism",
"feedback"
] | [
"regolith",
"fault_zone"
] | [
"soil",
"pore_water"
] | [
"landslide_and_mass_wasting",
"hydrological_partitioning_and_runoff"
] | hillslope_to_catchment | Steep Orogenic Hillslopes and Volcanic Edifices | instantaneous_to_event | Anthropocene | [
"high-resolution airborne/terrestrial LiDAR and structure-from-motion (SfM) topographic differencing",
"multi-temporal LiDAR/InSAR slope displacement fields, borehole inclinometers, and pore-pressure piezometers"
] | [
"basal pore-pressure diffusion and grain-inertia entrainment rates during debris-flow runout"
] | [
"Iverson undrained pore-pressure diffusion $\\partial_t p^* - D_{\\mathrm{hyd}} \\partial_{zz} p^* = -\\rho_s g \\dot{\\gamma} \\tan\\psi_{\\mathrm{dil}}$ and basal resistance $\\tau_b = (\\sigma_n - p_b) \\tan\\phi + \\tau_{\\mathrm{visc}}$",
"apparent Heim runout friction $\\mu_{\\mathrm{app}} = H_{\\mathrm{dro... | Formulated in SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022, SZ4D-LS1); corroborated across Li et al. (2025) and Yang et al. (2018). Remains open due to coupled extreme rainfall infiltration, coseismic strong ground shaking, and rapid snowmelt and regolith thickness, hillslope gradient, clay miner... | Co-located observations of high-resolution airborne/terrestrial LiDAR and structure-from-motion (SfM) topographic differencing and multi-temporal LiDAR/InSAR slope displacement fields, borehole inclinometers, and pore-pressure piezometers across Steep Orogenic Hillslopes and Volcanic Edifices coupled with process-resol... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,022 | E. E. Brodsky, T. A. Plank | 2026-10-16T00:00:00 | [
"UEARTH-000082",
"UEARTH-001574",
"UEARTH-000057"
] | [
"10.25740/hy589fc7561",
"10.1073/pnas.2417840121",
"10.1103/physreve.97.022906",
"10.25740/hy589fc7561"
] | [
"SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022), Landscapes and Seascapes (SZ4D-LS1), DOI:10.25740/hy589fc7561",
"Li et al. (2025), Proceedings of the National Academy of Sciences of the United States of America, DOI:10.1073/pnas.2417840121",
"Yang et al. (2018), Physical review. E, DOI:10... |
UEARTH-000082 | 82 | Submarine Landslide Triggering by Coseismic Pore-Pressure versus Gas-Hydrate Dissociation | What physical, chemical, and dynamical mechanisms determine what relative roles do cyclic seismic liquefaction of weak marine contourite layers, rapid sedimentation overpressure, and bottom-water warming gas-hydrate dissociation play in triggering giant continental-margin submarine landslides? | What natural processes determine what triggers massive underwater landslides along continental slopes that can generate destructive coastal tsunamis? | How can 3D marine seismic reflection headwall mapping, IODP geotechnical core piezocone tests, and tsunami runup hindcasts constrain infinite-slope effective stress factor of safety $\mathrm{FS} = [c' + (\gamma' z \cos^2 \beta - \Delta u_{\mathrm{exc}}) \tan \phi'] / (\gamma_{\mathrm{sat}} z \sin \beta \cos \beta)$ to ... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | landslide_debris_flow_mass_wasting | 3 | [
"mechanism",
"hazard_generation"
] | [
"regolith",
"fault_zone"
] | [
"soil",
"pore_water"
] | [
"landslide_and_mass_wasting",
"hydrological_partitioning_and_runoff"
] | hillslope_to_catchment | Steep Orogenic Hillslopes and Volcanic Edifices | instantaneous_to_event | Holocene | [
"multi-temporal LiDAR/InSAR slope displacement fields, borehole inclinometers, and pore-pressure piezometers",
"seismic acoustic emissions and flume/ring-shear basal friction measurements"
] | [
"transition from slow hillslope creep to catastrophic runaway acceleration via shear-zone liquefaction"
] | [
"Iverson undrained pore-pressure diffusion $\\partial_t p^* - D_{\\mathrm{hyd}} \\partial_{zz} p^* = -\\rho_s g \\dot{\\gamma} \\tan\\psi_{\\mathrm{dil}}$ and basal resistance $\\tau_b = (\\sigma_n - p_b) \\tan\\phi + \\tau_{\\mathrm{visc}}$",
"apparent Heim runout friction $\\mu_{\\mathrm{app}} = H_{\\mathrm{dro... | Formulated in SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022, SZ4D-LS2); corroborated across Gatter et al. (2021) and Kubota et al. (2017). Remains open due to coupled extreme rainfall infiltration, coseismic strong ground shaking, and rapid snowmelt and regolith thickness, hillslope gradient, clay... | Co-located observations of multi-temporal LiDAR/InSAR slope displacement fields, borehole inclinometers, and pore-pressure piezometers and seismic acoustic emissions and flume/ring-shear basal friction measurements across Steep Orogenic Hillslopes and Volcanic Edifices coupled with process-resolving models of landslide... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,022 | E. E. Brodsky, T. A. Plank | 2026-10-16T00:00:00 | [
"UEARTH-000081",
"UEARTH-001761",
"UEARTH-000065"
] | [
"10.25740/hy589fc7561",
"10.1016/j.earscirev.2021.103845",
"10.1002/2017gl075386",
"10.25740/hy589fc7561"
] | [
"SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022), Landscapes and Seascapes (SZ4D-LS2), DOI:10.25740/hy589fc7561",
"Gatter et al. (2021), Earth-Science Reviews, DOI:10.1016/j.earscirev.2021.103845",
"Kubota et al. (2017), Geophysical Research Letters, DOI:10.1002/2017gl075386",
"E. E. Brod... |
UEARTH-000083 | 83 | Induced Seismicity Maximum Magnitude and Poroelastic versus Pore-Pressure Stress Transfer | What physical, chemical, and dynamical mechanisms determine whether the maximum earthquake magnitude ($M_{\max}$) induced by subsurface fluid injection is bounded strictly by injected fluid volume ($\Delta V$) or controlled by tectonic background criticality and poroelastic stress transfer onto basement faults? | What natural processes determine what sets the maximum size of earthquakes triggered by underground wastewater disposal or geothermal fluid injection? | How can downhole microseismic arrays, InSAR poroelastic uplift inversions, and injection rate-pressure records constrain McGarr relation $\sum M_0 \le 2 \mu \Delta V$ versus Biot poroelastic Coulomb stress change $\Delta \mathrm{CFS} = \Delta \tau + \mu_f (\Delta \sigma_n + \alpha_B \Delta P_f)$ to resolve whether the ... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | earthquake_rupture_fault_mechanics | 1 | [
"mechanism"
] | [
"fault_zone",
"continental_crust"
] | [
"crystalline_rock",
"pore_water"
] | [
"fault_rupture_and_slip",
"crustal_deformation"
] | fault_or_volcanic_edifice | Plate-Boundary and Intraplate Seismogenic Fault Zones | instantaneous_to_event | Anthropocene | [
"multi-temporal InSAR surface displacement velocity fields and continuous GNSS station networks",
"near-field broadband seismograms, high-rate GNSS displacements, and InSAR coseismic interferograms"
] | [
"partitioning between seismic radiation, fracture energy, and off-fault plastic damage"
] | [
"rate-and-state friction $\\tau = \\sigma_n' [\\mu_0 + a \\ln(V/V_0) + b \\ln(V_0 \\theta / D_c)]$ with thermal pressurization $\\partial_t P_f = \\Lambda_{\\mathrm{TP}} \\tau V / w + D_{\\mathrm{hyd}} \\partial_{yy} P_f$",
"elastodynamic fracture energy balance $G_c = \\int_0^{D_c} (\\tau(u) - \\tau_r) du$ and c... | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q4c); corroborated across Glasgow et al. (2021) and Bedford et al. (2021). Remains partially solved due to coupled tectonic shear-stress loading and coseismic dynamic pore-pressure transients and fault-zone geometric complexity, gouge min... | Co-located observations of multi-temporal InSAR surface displacement velocity fields and continuous GNSS station networks and near-field broadband seismograms, high-rate GNSS displacements, and InSAR coseismic interferograms across Plate-Boundary and Intraplate Seismogenic Fault Zones coupled with process-resolving mod... | partially_solved | mechanism_known_magnitude_uncertain | PARTIAL-PROGRESS | true | medium | 3 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-001589",
"UEARTH-001568",
"UEARTH-000070"
] | [
"10.17226/25761",
"10.1029/2021jb022839",
"10.1016/j.epsl.2021.117161",
"10.25740/hy589fc7561"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Geohazards (EiT-Q4c), DOI:10.17226/25761",
"Glasgow et al. (2021), Journal of Geophysical Research Solid Earth, DOI:10.1029/2021jb022839",
"Bedford et al. (2021), Earth and Planetary Science Letters, DOI:10.1016/j.epsl.2021.117161",
"E. E. Brod... |
UEARTH-000084 | 84 | Pyroclastic Density Current Dilute-Surge versus Concentrated Basal-Flow Stratification | What physical, chemical, and dynamical mechanisms determine what turbulent particle-clustering, pore-gas fluidization, and topographic air-entrainment mechanisms control the decoupling of overriding dilute ash surges from concentrated basal pyroclastic flows and the transition to buoyant co-ignimbrite liftoff? | What natural processes determine how deadly volcanic ash flows split into a dense ground-hugging avalanche and a fast, buoyant ash cloud that can jump ridges? | How can large-scale experimental eruption flumes, Doppler radar ash-plume velocimetry, and pyroclastic deposit grain-size grading constrain Rouse number $\mathrm{Ro} = w_s / (\kappa u_*)$ and bulk Richardson number $\mathrm{Ri}_b = g' h \cos \theta / U^2$ in multiphase dusty gases to resolve what turbulent particle-clu... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | volcanic_plumbing_eruption_degassing | 3 | [
"mechanism"
] | [
"magma_reservoir",
"continental_crust"
] | [
"magma_or_melt",
"hydrothermal_fluid"
] | [
"volcanic_degassing_and_eruption",
"magma_generation_and_ascent"
] | fault_or_volcanic_edifice | Active Arc, Rift, and Hotspot Volcanic Systems | instantaneous_to_event | Holocene | [
"multi-spectral/active satellite remote sensing and Doppler radar vertical profile retrievals",
"edifice tilt/InSAR deformation, volcano-tectonic seismicity, and UV/FTIR SO2/CO2 gas plume ratios"
] | [
"crystal-mush remobilization timescales, conduit magma ascent rates, and effusive-to-explosive transitions"
] | [
"multiphase magma viscosity $\\eta(\\phi_c, C_{\\mathrm{H2O}}, T) = \\eta_{\\mathrm{melt}}(C_{\\mathrm{H2O}}, T) (1 - \\phi_c / \\phi_m)^{-B \\phi_m}$ and Deborah fragmentation criterion $\\mathrm{De} = \\eta \\dot{\\gamma} / G_\\infty \\ge 10^{-2}$",
"conduit momentum-continuity balance $\\rho_m u \\partial_z u ... | Formulated in Volcanic Eruptions and Their Repose, Unrest, Precursors, and Timing (ERUPT) (2017, ERUPT-GC5); corroborated across Katsura (2017) and Xu et al. (2018). Remains open due to coupled mafic magma recharge, volatile exsolution buoyancy, and conduit shear heating and magma viscosity, conduit geometry, and edifi... | Co-located observations of multi-spectral/active satellite remote sensing and Doppler radar vertical profile retrievals and edifice tilt/InSAR deformation, volcano-tectonic seismicity, and UV/FTIR SO2/CO2 gas plume ratios across Active Arc, Rift, and Hotspot Volcanic Systems coupled with process-resolving models of vol... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,017 | Committee on Improving Understanding of Volcanic Eruptions, M. Manga (Chair) | 2026-10-16T00:00:00 | [
"UEARTH-000078",
"UEARTH-002372",
"UEARTH-000259"
] | [
"10.17226/24650",
"10.2465/gkk.161209",
"10.1016/j.agrformet.2017.03.004",
"10.25740/hy589fc7561"
] | [
"Volcanic Eruptions and Their Repose, Unrest, Precursors, and Timing (ERUPT) (2017), Volcano Hazards (ERUPT-GC5), DOI:10.17226/24650",
"Katsura (2017), Japanese Magazine of Mineralogical and Petrological Sciences, DOI:10.2465/gkk.161209",
"Xu et al. (2018), Agricultural and Forest Meteorology., DOI:10.1016/j.ag... |
UEARTH-000085 | 85 | Postseismic Afterslip versus Viscoelastic Mantle Relaxation Partitioning | What physical, chemical, and dynamical mechanisms determine how to uniquely separate fault-plane frictional afterslip from lower-crustal and mantle-wedge transient viscoelastic relaxation in decadal postseismic GNSS and InSAR deformation fields following great earthquakes? | What natural processes determine how much of the ground movement in the years after a giant earthquake comes from deep rock flowing versus the fault continuing to creep? | How can seafloor + land-based continuous GNSS networks, GRACE satellite gravity changes, and laboratory olivine transient creep laws constrain velocity-strengthening afterslip $V(t) = V_0 [1 + t / t_a]^{-1}$ versus Burgers transient/steady-state viscoelastic creep compliance $J(t)$ to resolve how to uniquely separate f... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | earthquake_rupture_fault_mechanics | 3 | [
"mechanism",
"budget"
] | [
"fault_zone",
"continental_crust"
] | [
"crystalline_rock",
"pore_water"
] | [
"fault_rupture_and_slip",
"crustal_deformation"
] | fault_or_volcanic_edifice | Plate-Boundary and Intraplate Seismogenic Fault Zones | instantaneous_to_event | Anthropocene | [
"multi-temporal InSAR surface displacement velocity fields and continuous GNSS station networks",
"GRACE/GRACE-FO satellite gravimetry terrestrial water storage and ice-mass anomaly fields"
] | [
"partitioning between seismic radiation, fracture energy, and off-fault plastic damage"
] | [
"rate-and-state friction $\\tau = \\sigma_n' [\\mu_0 + a \\ln(V/V_0) + b \\ln(V_0 \\theta / D_c)]$ with thermal pressurization $\\partial_t P_f = \\Lambda_{\\mathrm{TP}} \\tau V / w + D_{\\mathrm{hyd}} \\partial_{yy} P_f$",
"elastodynamic fracture energy balance $G_c = \\int_0^{D_c} (\\tau(u) - \\tau_r) du$ and c... | Formulated in SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022, SZ4D-FEC5); corroborated across Katsura (2017) and Liu et al. (2023). Remains open due to coupled tectonic shear-stress loading and coseismic dynamic pore-pressure transients and fault-zone geometric complexity, gouge mineralogy, and dep... | Co-located observations of multi-temporal InSAR surface displacement velocity fields and continuous GNSS station networks and GRACE/GRACE-FO satellite gravimetry terrestrial water storage and ice-mass anomaly fields across Plate-Boundary and Intraplate Seismogenic Fault Zones coupled with process-resolving models of fa... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,022 | E. E. Brodsky, T. A. Plank | 2026-10-16T00:00:00 | [
"UEARTH-000073",
"UEARTH-001493",
"UEARTH-000059"
] | [
"10.25740/hy589fc7561",
"10.2465/gkk.161209",
"10.1785/0220230075",
"10.25740/hy589fc7561"
] | [
"SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022), Fault Mechanics (SZ4D-FEC5), DOI:10.25740/hy589fc7561",
"Katsura (2017), Japanese Magazine of Mineralogical and Petrological Sciences, DOI:10.2465/gkk.161209",
"Liu et al. (2023), Seismological Research Letters, DOI:10.1785/0220230075",
"E... |
UEARTH-000086 | 86 | Post-Earthquake and Post-Eruption Sediment Pulse Cascades and River Aggradation | What physical, chemical, and dynamical mechanisms determine how long coseismic landslide debris and volcanic tephra blankets remain stored on steep hillslopes before monsoon or atmospheric-river storms mobilize them into downstream debris-flow and channel-aggradation cascades? | What natural processes determine how long landslide rubble and volcanic ash sit on mountain slopes after a disaster before storms wash them down to bury valleys? | How can multi-temporal LiDAR DEM differencing, suspended-sediment turbidity gauges, and cosmogenic $^{10}\mathrm{Be}$ dilution series constrain hillslope-channel sediment mass balance $\partial S_h / \partial t = I_{\mathrm{coseis}} \delta(t) - k_m (Q - Q_c)^m S_h$ to resolve how long coseismic landslide debris and vol... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | earthquake_rupture_fault_mechanics | 3 | [
"mechanism",
"hazard_generation"
] | [
"fault_zone",
"continental_crust"
] | [
"crystalline_rock",
"pore_water"
] | [
"fault_rupture_and_slip",
"crustal_deformation"
] | fault_or_volcanic_edifice | Plate-Boundary and Intraplate Seismogenic Fault Zones | instantaneous_to_event | Holocene | [
"in-situ terrestrial cosmogenic nuclide (10Be, 26Al) surface exposure and denudation inventories",
"high-resolution airborne/terrestrial LiDAR and structure-from-motion (SfM) topographic differencing"
] | [
"rate-and-state frictional healing, dynamic pore-fluid pressurization, and rupture arrest thresholds"
] | [
"rate-and-state friction $\\tau = \\sigma_n' [\\mu_0 + a \\ln(V/V_0) + b \\ln(V_0 \\theta / D_c)]$ with thermal pressurization $\\partial_t P_f = \\Lambda_{\\mathrm{TP}} \\tau V / w + D_{\\mathrm{hyd}} \\partial_{yy} P_f$",
"elastodynamic fracture energy balance $G_c = \\int_0^{D_c} (\\tau(u) - \\tau_r) du$ and c... | Formulated in SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022, SZ4D-LS3); corroborated across Zhou et al. (2022) and Juan et al. (2026). Remains open due to coupled tectonic shear-stress loading and coseismic dynamic pore-pressure transients and fault-zone geometric complexity, gouge mineralogy, and... | Co-located observations of in-situ terrestrial cosmogenic nuclide (10Be, 26Al) surface exposure and denudation inventories and high-resolution airborne/terrestrial LiDAR and structure-from-motion (SfM) topographic differencing across Plate-Boundary and Intraplate Seismogenic Fault Zones coupled with process-resolving m... | open | mechanism_known_magnitude_uncertain | OPEN-VERIFIED | true | medium | 3 | 2,022 | E. E. Brodsky, T. A. Plank | 2026-10-16T00:00:00 | [
"UEARTH-000073",
"UEARTH-001529",
"UEARTH-000138"
] | [
"10.25740/hy589fc7561",
"10.1029/2021gc009839",
"10.1093/ismejo/wrag048",
"10.25740/hy589fc7561"
] | [
"SZ4D Implementation Plan: Subduction Zones in Four Dimensions (2022), Geohazard Cascades (SZ4D-LS3), DOI:10.25740/hy589fc7561",
"Zhou et al. (2022), Geochemistry Geophysics Geosystems, DOI:10.1029/2021gc009839",
"Juan et al. (2026), The ISME journal, DOI:10.1093/ismejo/wrag048",
"E. E. Brodsky, T. A. Plank, ... |
UEARTH-000087 | 87 | Hydrothermal Seal Breakdown and Phreatic Eruption Triggering Without Magma Extrusion | What physical, chemical, and dynamical mechanisms determine how self-sealing silica/alunite alteration caps above shallow volcano-hydrothermal systems accumulate magmatic gas overpressure and rupture explosively in sudden phreatic eruptions with minimal precursory deformation? | What natural processes determine why steam-driven volcanic explosions happen suddenly when mineral crusts trap high-pressure gas beneath a volcano? | How can broadband volcano-seismic tremor/VLP polarization, Magnetotelluric clay-cap imaging, and Multi-GAS $\mathrm{H}_2\mathrm{S}/\mathrm{SO}_2$ ratios constrain hydrofracture criterion $P_{\mathrm{fluid}} \ge \sigma_3 + T_0$ across low-permeability ($k \le 10^{-19}\,\mathrm{m^2}$) acid-sulfate alteration seals to re... | earthquakes_volcanoes_tsunamis_geohazards | 2 | Earthquakes, Volcanoes, Tsunamis, and Geohazards | volcanic_plumbing_eruption_degassing | 3 | [
"mechanism",
"hazard_generation"
] | [
"magma_reservoir",
"continental_crust"
] | [
"magma_or_melt",
"hydrothermal_fluid"
] | [
"volcanic_degassing_and_eruption",
"magma_generation_and_ascent"
] | fault_or_volcanic_edifice | Active Arc, Rift, and Hotspot Volcanic Systems | instantaneous_to_event | Anthropocene | [
"deep magnetotelluric (MT) and electrical resistivity tomography (ERT) conductivity inversions",
"edifice tilt/InSAR deformation, volcano-tectonic seismicity, and UV/FTIR SO2/CO2 gas plume ratios"
] | [
"volatile exsolution kinetics and overpressure thresholds triggering dike propagation"
] | [
"multiphase magma viscosity $\\eta(\\phi_c, C_{\\mathrm{H2O}}, T) = \\eta_{\\mathrm{melt}}(C_{\\mathrm{H2O}}, T) (1 - \\phi_c / \\phi_m)^{-B \\phi_m}$ and Deborah fragmentation criterion $\\mathrm{De} = \\eta \\dot{\\gamma} / G_\\infty \\ge 10^{-2}$",
"conduit momentum-continuity balance $\\rho_m u \\partial_z u ... | Formulated in Volcanic Eruptions and Their Repose, Unrest, Precursors, and Timing (ERUPT) (2017, ERUPT-GC6); corroborated across Aizawa et al. (2026) and Scudero et al. (2019). Remains open due to coupled mafic magma recharge, volatile exsolution buoyancy, and conduit shear heating and magma viscosity, conduit geometry... | Co-located observations of deep magnetotelluric (MT) and electrical resistivity tomography (ERT) conductivity inversions and edifice tilt/InSAR deformation, volcano-tectonic seismicity, and UV/FTIR SO2/CO2 gas plume ratios across Active Arc, Rift, and Hotspot Volcanic Systems coupled with process-resolving models of vo... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,017 | Committee on Improving Understanding of Volcanic Eruptions, M. Manga (Chair) | 2026-10-16T00:00:00 | [
"UEARTH-000076",
"UEARTH-000077",
"UEARTH-000061"
] | [
"10.17226/24650",
"10.1029/2025gl120131",
"10.1038/s41598-019-40563-0",
"10.25740/hy589fc7561"
] | [
"Volcanic Eruptions and Their Repose, Unrest, Precursors, and Timing (ERUPT) (2017), Volcano Physics (ERUPT-GC6), DOI:10.17226/24650",
"Aizawa et al. (2026), Geophysical Research Letters, DOI:10.1029/2025gl120131",
"Scudero et al. (2019), Scientific Reports, DOI:10.1038/s41598-019-40563-0",
"E. E. Brodsky, T.... |
UEARTH-000088 | 88 | Mantle Wedge Oxidation State Origin in Subduction-Zone Arc Magmas | What physical, chemical, and dynamical mechanisms determine whether the elevated oxygen fugacity ($\Delta \mathrm{FMQ} +1$ to $+3$) of island-arc basalts relative to mid-ocean ridge basalts is inherited from oxidized subducted slab fluids ($\mathrm{S}^{6+}, \mathrm{Fe}^{3+}, \mathrm{C}^{4+}$) or generated during intrac... | What natural processes determine whether arc volcanoes are more oxidized than mid-ocean ridges because sinking plates bring down oxygen-rich fluids or because the magma changes as it rises? | How can olivine-hosted melt-inclusion $\mathrm{Fe}^{3+}/\sum \mathrm{Fe}$ micro-XANES and eclogite fluid-inclusion speciation constrain redox buffer equilibrium $6\,\mathrm{Fe}_2\mathrm{O}_3 \rightleftharpoons 4\,\mathrm{Fe}_3\mathrm{O}_4 + \mathrm{O}_2$ and $\mathrm{V/Sc}$, $\mathrm{Zn/Fe}$, and Fe-XANES valence syste... | geochemistry_mineralogy_petrology_earth_materials | 3 | Geochemistry, Mineralogy, Petrology, and Earth Materials | igneous_petrology_magmatic_differentiation | 1 | [
"mechanism"
] | [
"magma_reservoir",
"continental_crust"
] | [
"magma_or_melt",
"crystalline_rock"
] | [
"magma_generation_and_ascent",
"metamorphic_transformation"
] | core_to_outcrop | Crustal and Upper-Mantle Magmatic Provinces | multi_million_year_tectonic | Cenozoic | [
"synchrotron X-ray absorption spectroscopy (EXAFS/XANES) and high-resolution molecular spectroscopy",
"electron microprobe and LA-ICP-MS mineral/melt-inclusion major and trace element zoning"
] | [
"degree of partial melting, crustal assimilation vs. fractional crystallization (AFC) mass balance"
] | [
"open-system assimilation-fractional crystallization (AFC) $dC_m/dF = [r/(r-1)] C_a / F - D_{\\mathrm{bulk}} C_m / F$ and oxygen fugacity $\\Delta \\mathrm{FMQ}$",
"McKenzie compaction length $\\delta_c = \\sqrt{k_\\phi (\\zeta + 4\\eta/3) / \\mu_f}$ governing melt extraction from crystal mush"
] | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q3f); corroborated across Zhang et al. (2021) and Song et al. (2025). Remains open due to coupled decompression melting, mantle heat flux, and flux melting by slab-derived volatiles and source rock fertility, oxygen fugacity (fO2), and pr... | Co-located observations of synchrotron X-ray absorption spectroscopy (EXAFS/XANES) and high-resolution molecular spectroscopy and electron microprobe and LA-ICP-MS mineral/melt-inclusion major and trace element zoning across Crustal and Upper-Mantle Magmatic Provinces coupled with process-resolving models of magma gene... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-000103",
"UEARTH-002518",
"UEARTH-000348"
] | [
"10.17226/25761",
"10.1126/sciadv.abj2515",
"10.1016/j.scib.2025.09.046",
"10.6075/J0W66J9H"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Geochemical Cycles (EiT-Q3f), DOI:10.17226/25761",
"Zhang et al. (2021), Science advances, DOI:10.1126/sciadv.abj2515",
"Song et al. (2025), Science bulletin, DOI:10.1016/j.scib.2025.09.046",
"A. A. P. Koppers and R. Coggon (Eds.) (2020), Explo... |
UEARTH-000089 | 89 | Porphyry Copper-Gold Fertility and Transcrustal Sulfide Saturation Timing | What physical, chemical, and dynamical mechanisms determine whether giant porphyry $\mathrm{Cu\text{--}Au\text{--}Mo}$ deposits require oxidized hydrous arc magmas that suppress early sulfide saturation, or whether lower-crustal sulfide cumulates act as pre-concentrated metal reservoirs remobilized by late volatile exs... | What natural processes determine what special magma chemistry allows giant copper and gold deposits to form beneath certain volcanoes while most remain barren? | How can zircon $\mathrm{Ce}^{4+}/\mathrm{Ce}^{3+}$ and $\mathrm{Eu/Eu^*}$ oxy-hygrometry, lower-crustal xenolith sulfides, and fluid-inclusion LA-ICP-MS constrain chalcophile partition coefficients $D_{\mathrm{Cu,Au}}^{\mathrm{sulfide/silicate}} \sim 10^3\text{--}10^4$ vs. $D_{\mathrm{Cu}}^{\mathrm{fluid/melt}}(X_{\mat... | geochemistry_mineralogy_petrology_earth_materials | 3 | Geochemistry, Mineralogy, Petrology, and Earth Materials | hydrothermal_ore_deposits_metallogeny | 1 | [
"mechanism",
"reconstruction"
] | [
"hydrothermal_system",
"continental_crust"
] | [
"hydrothermal_fluid",
"crystalline_rock"
] | [
"redox_transformation",
"magma_generation_and_ascent"
] | core_to_outcrop | Magmatic–Hydrothermal and Submarine Metallogenic Belts | multi_million_year_tectonic | Cenozoic | [
"laser-ablation ICP-MS/SIMS zircon U-Pb geochronology and Lu-Hf isotope ratios",
"fluid-inclusion microthermometry, Raman spectroscopy, and LA-ICP-MS single-inclusion metal assays"
] | [
"magmatic-hydrothermal fluid flux budgets and structural permeability focusing mechanisms"
] | [
"fluid-melt metal partitioning $D_M^{\\mathrm{fluid/melt}}(P, T, X_{\\mathrm{Cl}}, X_{\\mathrm{S}}, f\\mathrm{O}_2)$ and Helgeson-Kirkham-Flowers log $K(T, \\rho_w)$",
"chalcophile sulfide-silicate partitioning $D_{\\mathrm{Cu,Au}}^{\\mathrm{sulf/sil}} \\sim 10^3\\text{--}10^5$ vs. volatile saturation timing"
] | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q3g); corroborated across Gruzdeva et al. (2025) and Meng et al. (2021). Remains open due to coupled magmatic fluid exsolution, decompression boiling, and fluid-rock redox reactions and host-rock buffering capacity, fault-fracture network... | Co-located observations of laser-ablation ICP-MS/SIMS zircon U-Pb geochronology and Lu-Hf isotope ratios and fluid-inclusion microthermometry, Raman spectroscopy, and LA-ICP-MS single-inclusion metal assays across Magmatic–Hydrothermal and Submarine Metallogenic Belts coupled with process-resolving models of redox tran... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-002860",
"UEARTH-000090",
"UEARTH-000114"
] | [
"10.17226/25761",
"10.1038/s41598-025-15335-8",
"10.1038/s41467-021-22349-z",
"10.6075/J0W66J9H"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Critical Minerals (EiT-Q3g), DOI:10.17226/25761",
"Gruzdeva et al. (2025), Scientific reports, DOI:10.1038/s41598-025-15335-8",
"Meng et al. (2021), Nature communications, DOI:10.1038/s41467-021-22349-z",
"A. A. P. Koppers and R. Coggon (Eds.) ... |
UEARTH-000090 | 90 | Rare Earth Element (REE) Enrichment via Carbonatite Liquid Immiscibility versus Hydrothermal F-Cl Transport | What physical, chemical, and dynamical mechanisms determine what relative roles do silicate-carbonatite liquid immiscibility, extreme fractional crystallization, and late-stage fluoride/sulfate/chloride hydrothermal mobilization play in concentrating Rare Earth Elements to ore grades? | What natural processes determine how rare earth elements become concentrated into rich mineral deposits inside carbon-rich magmas and hot fluids? | How can heated diamond-anvil cell in-situ X-ray fluorescence, bastnäsite/monazite U-Th-Pb geochronology, and Nd-Sr-C-O isotopes constrain liquid-liquid partition coefficient $D_{\mathrm{REE}}^{\mathrm{carb/sil}}(P, T, X_{\mathrm{P,F,Na}})$ and aqueous $\mathrm{REEF}^{2+} / \mathrm{REECl}^{2+}$ stability constants to re... | geochemistry_mineralogy_petrology_earth_materials | 3 | Geochemistry, Mineralogy, Petrology, and Earth Materials | hydrothermal_ore_deposits_metallogeny | 1 | [
"mechanism",
"transport"
] | [
"hydrothermal_system",
"continental_crust"
] | [
"hydrothermal_fluid",
"crystalline_rock"
] | [
"redox_transformation",
"magma_generation_and_ascent"
] | core_to_outcrop | Magmatic–Hydrothermal and Submarine Metallogenic Belts | multi_million_year_tectonic | Cenozoic | [
"fluid-inclusion microthermometry, Raman spectroscopy, and LA-ICP-MS single-inclusion metal assays",
"in-situ sulfur, oxygen, and copper/iron/zinc stable isotope zoning across ore paragenetic stages"
] | [
"metal-ligand complex stability, phase-separation brine/vapor partitioning, and precipitation triggers"
] | [
"fluid-melt metal partitioning $D_M^{\\mathrm{fluid/melt}}(P, T, X_{\\mathrm{Cl}}, X_{\\mathrm{S}}, f\\mathrm{O}_2)$ and Helgeson-Kirkham-Flowers log $K(T, \\rho_w)$",
"chalcophile sulfide-silicate partitioning $D_{\\mathrm{Cu,Au}}^{\\mathrm{sulf/sil}} \\sim 10^3\\text{--}10^5$ vs. volatile saturation timing"
] | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q3h); corroborated across Deng et al. (2026) and Cai et al. (2023). Remains open due to coupled magmatic fluid exsolution, decompression boiling, and fluid-rock redox reactions and host-rock buffering capacity, fault-fracture network conn... | Co-located observations of fluid-inclusion microthermometry, Raman spectroscopy, and LA-ICP-MS single-inclusion metal assays and in-situ sulfur, oxygen, and copper/iron/zinc stable isotope zoning across ore paragenetic stages across Magmatic–Hydrothermal and Submarine Metallogenic Belts coupled with process-resolving m... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-002725",
"UEARTH-003490",
"UEARTH-000065"
] | [
"10.17226/25761",
"10.1130/g54294.1",
"10.1016/j.oregeorev.2023.105679",
"10.6075/J0W66J9H"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Critical Minerals (EiT-Q3h), DOI:10.17226/25761",
"Deng et al. (2026), Geology, DOI:10.1130/g54294.1",
"Cai et al. (2023), Ore Geology Reviews, DOI:10.1016/j.oregeorev.2023.105679",
"A. A. P. Koppers and R. Coggon (Eds.) (2020), Exploring Earth... |
UEARTH-000091 | 91 | Lithium Pegmatite Petrogenesis: Extreme Granite Fractionation versus Metasedimentary Anatexis | What physical, chemical, and dynamical mechanisms determine whether lithium-cesium-tantalum (LCT) spodumene pegmatites form through extreme ($\ge 99\%$) fractional crystallization of parental fertile S-type granites or direct low-degree partial melting of Li-rich metasedimentary rocks? | What natural processes determine whether lithium-rich pegmatite rocks form from the last dregs of cooling granite magma or by directly melting lithium-rich sedimentary rocks? | How can $\delta^7\mathrm{Li}$ and $\delta^{11}\mathrm{B}$ mineral zoning, quartz trace-element (Al, Ti, Ge) thermometry, and melt inclusions constrain Rayleigh fractionation $C_L / C_0 = F^{(D_{\mathrm{Li}} - 1)}$ with undercooled constitutional zone refining ($\Delta T_{\mathrm{undercool}} \sim 100\text{--}200\,^\circ... | geochemistry_mineralogy_petrology_earth_materials | 3 | Geochemistry, Mineralogy, Petrology, and Earth Materials | igneous_petrology_magmatic_differentiation | 1 | [
"mechanism"
] | [
"magma_reservoir",
"continental_crust"
] | [
"magma_or_melt",
"crystalline_rock"
] | [
"magma_generation_and_ascent",
"metamorphic_transformation"
] | core_to_outcrop | Crustal and Upper-Mantle Magmatic Provinces | multi_million_year_tectonic | Cenozoic | [
"electron microprobe and LA-ICP-MS mineral/melt-inclusion major and trace element zoning",
"piston-cylinder and multi-anvil phase-equilibrium experiments and radiogenic Sr-Nd-Hf isotopes"
] | [
"melt extraction percolation thresholds and volatile/chalcophile partitioning coefficients"
] | [
"open-system assimilation-fractional crystallization (AFC) $dC_m/dF = [r/(r-1)] C_a / F - D_{\\mathrm{bulk}} C_m / F$ and oxygen fugacity $\\Delta \\mathrm{FMQ}$",
"McKenzie compaction length $\\delta_c = \\sqrt{k_\\phi (\\zeta + 4\\eta/3) / \\mu_f}$ governing melt extraction from crystal mush"
] | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q3i); corroborated across Xu et al. (2025) and Shah (2025). Remains open due to coupled decompression melting, mantle heat flux, and flux melting by slab-derived volatiles and source rock fertility, oxygen fugacity (fO2), and pressure-tem... | Co-located observations of electron microprobe and LA-ICP-MS mineral/melt-inclusion major and trace element zoning and piston-cylinder and multi-anvil phase-equilibrium experiments and radiogenic Sr-Nd-Hf isotopes across Crustal and Upper-Mantle Magmatic Provinces coupled with process-resolving models of magma generati... | open | active_debate | OPEN-VERIFIED | true | medium | 3 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-002601",
"UEARTH-002721",
"UEARTH-000056"
] | [
"10.17226/25761",
"10.1038/s41598-025-13607-x",
"10.1016/j.actbio.2025.01.055",
"10.6075/J0W66J9H"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Critical Minerals (EiT-Q3i), DOI:10.17226/25761",
"Xu et al. (2025), Scientific reports, DOI:10.1038/s41598-025-13607-x",
"Shah (2025), Acta biomaterialia, DOI:10.1016/j.actbio.2025.01.055",
"A. A. P. Koppers and R. Coggon (Eds.) (2020), Explor... |
UEARTH-000092 | 92 | Deep Subduction Carbon Recycling Efficiency Versus Forearc-to-Subarc Carbonate Dissolution | What physical, chemical, and dynamical mechanisms determine what fraction of subducted marine carbonate and organic carbon is mobilized into the forearc and arc crust via metamorphic decarbonation versus incongruent aqueous dissolution at high pressure ($2\text{--}6\,\mathrm{GPa}$), and how much reaches the deep mantle... | What natural processes determine how much carbon on sinking ocean plates dissolves and returns to the atmosphere through volcanoes versus sinking into the deep mantle? | How can exhumed high-pressure lawsonite/eclogite carbonate veins, $\delta^{13}\mathrm{C}\text{--}^3\mathrm{He}/^4\mathrm{He}$ volcanic gas budgets, and piston-cylinder dissolution experiments constrain high-pressure dielectric constant of water $\varepsilon_{\mathrm{H2O}}(P, T)$ governing $\mathrm{CaCO}_3$ ionic solubi... | geochemistry_mineralogy_petrology_earth_materials | 3 | Geochemistry, Mineralogy, Petrology, and Earth Materials | low_temp_aqueous_clay_sorption_interface | 3 | [
"mechanism",
"budget"
] | [
"critical_zone",
"regolith"
] | [
"pore_water",
"sediment"
] | [
"chemical_weathering",
"redox_transformation"
] | molecular_to_pore | Near-Surface Mineral–Water Interfaces and Regolith | instantaneous_to_event | Holocene | [
"synchrotron X-ray absorption spectroscopy (EXAFS/XANES) and in-situ vibrational spectroscopy",
"sorption isotherms, diffusive gradients in thin films (DGT), and aqueous speciation titrations"
] | [
"inner- versus outer-sphere surface complexation thermodynamics and interfacial hydration energetics"
] | [
"Transition State Theory dissolution rate $r = k_+ A_{\\mathrm{reactive}} \\prod a_i^{n_i} [1 - \\exp(\\Delta G_r / (\\sigma R T))]$",
"surface complexation triple-layer electrostatic equilibrium $K_{\\mathrm{int}} = K_{\\mathrm{app}} \\exp(F \\Delta Z \\Psi_0 / R T)$"
] | Formulated in Exploring Earth by Scientific Ocean Drilling: 2050 Science Framework (2020, IODP-SO1b); corroborated across Zhang et al. (2026) and Jin et al. (2023). Remains open due to coupled pH/Eh gradients, ionic strength fluctuations, and organic ligand complexation and mineral surface site density, interlayer basa... | Co-located observations of synchrotron X-ray absorption spectroscopy (EXAFS/XANES) and in-situ vibrational spectroscopy and sorption isotherms, diffusive gradients in thin films (DGT), and aqueous speciation titrations across Near-Surface Mineral–Water Interfaces and Regolith coupled with process-resolving models of ch... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,020 | A. A. P. Koppers, R. Coggon | 2026-10-16T00:00:00 | [
"UEARTH-002990",
"UEARTH-000101",
"UEARTH-000107"
] | [
"10.6075/J0W66J9H",
"10.1126/sciadv.aee3217",
"10.1073/pnas.2219083120",
"10.6075/J0W66J9H"
] | [
"Exploring Earth by Scientific Ocean Drilling: 2050 Science Framework (2020), Deep Carbon Cycle (IODP-SO1b), DOI:10.6075/J0W66J9H",
"Zhang et al. (2026), Science advances, DOI:10.1126/sciadv.aee3217",
"Jin et al. (2023), Proceedings of the National Academy of Sciences of the United States of America, DOI:10.107... |
UEARTH-000093 | 93 | Laboratory-to-Field Silicate Weathering Rate Discrepancy Across Five Orders of Magnitude | What physical, chemical, and dynamical mechanisms determine why field-measured chemical dissolution rates of plagioclase and K-feldspar in natural soils and aquifers are $10^2\text{--}10^5$ times slower than far-from-equilibrium laboratory reactor rates? | What natural processes determine why silicate minerals dissolve up to 100,000 times slower in natural soils than in laboratory beakers? | How can atomic-force microscopy/vertical scanning interferometry, NanoSIMS leached-layer profiles, and catchment $\mathrm{Li/Mg}$ isotope mass balances constrain Transition State Theory rate law $r = k_+ A_{\mathrm{reactive}} (a_{\mathrm{H^+}})^n [1 - \exp(\Delta G_r / \sigma RT)]$ and amorphous silica surface passivat... | geochemistry_mineralogy_petrology_earth_materials | 3 | Geochemistry, Mineralogy, Petrology, and Earth Materials | isotope_geochemistry_geochronology | 7 | [
"mechanism",
"rate"
] | [
"continental_crust",
"lithosphere"
] | [
"crystalline_rock",
"rock"
] | [
"metamorphic_transformation",
"chemical_weathering"
] | core_to_outcrop | Crustal and Mantle Geochemical Reservoirs | geological_deep_time | Cenozoic | [
"MC-ICP-MS, SIMS, and TIMS high-precision radiogenic and non-traditional stable isotope ratios",
"ab-initio density-functional-theory (DFT) vibrational force constants and diffusion profiles"
] | [
"closure temperatures, radiation-damage annealing kinetics, and crustal residence timescales"
] | [
"Urey-Bigeleisen-Mayer equilibrium fractionation $10^3 \\ln \\alpha_{A-B} \\approx A \\Delta \\langle F \\rangle / T^2$ vs. kinetic/diffusive fractionation $(m_1/m_2)^\\beta$",
"Dodson diffusive closure temperature $T_c = E_a / [R \\ln(A \\tau D_0 / a^2)]$ modified by alpha-recoil damage fraction $f_a$"
] | Formulated in Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth (2017, CZO-Min1); corroborated across Gaspard et al. (2021) and Shah (2025). Remains open due to coupled thermal diffusion, metamorphic recrystallization, and redox phase partitioning and crystal lattice... | Co-located observations of MC-ICP-MS, SIMS, and TIMS high-precision radiogenic and non-traditional stable isotope ratios and ab-initio density-functional-theory (DFT) vibrational force constants and diffusion profiles across Crustal and Mantle Geochemical Reservoirs coupled with process-resolving models of metamorphic ... | open | scale_dependent_disagreement | OPEN-VERIFIED | true | hard | 4 | 2,017 | S. L. Brantley, W. H. McDowell | 2026-10-16T00:00:00 | [
"UEARTH-002782",
"UEARTH-002890",
"UEARTH-000269"
] | [
"10.5194/esurf-5-841-2017",
"10.1029/2021gc009904",
"10.1016/j.actbio.2025.01.055",
"10.6075/J0W66J9H"
] | [
"Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth (2017), Mineral-Water Interfaces (CZO-Min1), DOI:10.5194/esurf-5-841-2017",
"Gaspard et al. (2021), Geochemistry Geophysics Geosystems, DOI:10.1029/2021gc009904",
"Shah (2025), Acta biomaterialia, DOI:10.1016... |
UEARTH-000094 | 94 | Non-Classical Nucleation via Pre-Nucleation Clusters and Amorphous Precursors in Earth Materials | What physical, chemical, and dynamical mechanisms govern under what aqueous supersaturation and organic-ligand conditions do carbonate, iron-oxyhydroxide, and silicate minerals crystallize via non-classical particle attachment of amorphous nanoparticles rather than monomer-by-monomer classical nucleation? | What natural processes explain when minerals grow in water by clumping tiny amorphous nanoparticles together rather than adding single atoms one by one? | How can in-situ liquid-cell TEM, synchrotron small-angle X-ray scattering (SAXS), and cryogenic pair-distribution function analysis constrain free-energy barrier $\Delta G^* = (16 \pi \gamma^3 v_m^2) / [3 (k_B T \ln \Omega)^2]$ vs. oriented attachment and Ostwald step-rule pathways to resolve under what aqueous supersa... | geochemistry_mineralogy_petrology_earth_materials | 3 | Geochemistry, Mineralogy, Petrology, and Earth Materials | low_temp_aqueous_clay_sorption_interface | 7 | [
"mechanism"
] | [
"critical_zone",
"regolith"
] | [
"pore_water",
"sediment"
] | [
"chemical_weathering",
"redox_transformation"
] | molecular_to_pore | Near-Surface Mineral–Water Interfaces and Regolith | instantaneous_to_event | Holocene | [
"synchrotron X-ray absorption spectroscopy (EXAFS/XANES) and high-resolution molecular spectroscopy",
"synchrotron X-ray absorption spectroscopy (EXAFS/XANES) and in-situ vibrational spectroscopy"
] | [
"inner- versus outer-sphere surface complexation thermodynamics and interfacial hydration energetics"
] | [
"Transition State Theory dissolution rate $r = k_+ A_{\\mathrm{reactive}} \\prod a_i^{n_i} [1 - \\exp(\\Delta G_r / (\\sigma R T))]$",
"surface complexation triple-layer electrostatic equilibrium $K_{\\mathrm{int}} = K_{\\mathrm{app}} \\exp(F \\Delta Z \\Psi_0 / R T)$"
] | Formulated in Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth (2017, CZO-Min2); corroborated across Tadayon et al. (2024) and Li et al. (2026). Remains open due to coupled pH/Eh gradients, ionic strength fluctuations, and organic ligand complexation and mineral sur... | Co-located observations of synchrotron X-ray absorption spectroscopy (EXAFS/XANES) and high-resolution molecular spectroscopy and synchrotron X-ray absorption spectroscopy (EXAFS/XANES) and in-situ vibrational spectroscopy across Near-Surface Mineral–Water Interfaces and Regolith coupled with process-resolving models o... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | medium | 3 | 2,017 | S. L. Brantley, W. H. McDowell | 2026-10-16T00:00:00 | [
"UEARTH-002680",
"UEARTH-003148",
"UEARTH-003685"
] | [
"10.5194/esurf-5-841-2017",
"10.1016/j.cocis.2024.101859",
"10.1128/aem.00954-26",
"10.6075/J0W66J9H"
] | [
"Designing a network of critical zone observatories to explore the living skin of the terrestrial Earth (2017), Mineral-Water Interfaces (CZO-Min2), DOI:10.5194/esurf-5-841-2017",
"Tadayon et al. (2024), Current Opinion in Colloid & Interface Science, DOI:10.1016/j.cocis.2024.101859",
"Li et al. (2026), Applied... |
UEARTH-000095 | 95 | Equilibrium versus Kinetic Fractionation of Non-Traditional Stable Isotopes in High-Temperature Systems | What physical, chemical, and dynamical mechanisms determine how to separate equilibrium bond-stiffness fractionation from thermal/chemical diffusion (Soret and chemical potential gradients) in non-traditional stable isotopes ($\mathrm{Fe, Mg, Si, Ca, Ti, V, Mo, Ba}$) during magmatic differentiation? | What natural processes determine how to tell whether heavy and light metal isotopes in igneous rocks separated peacefully at equilibrium or by fast diffusion during cooling? | How can high-precision MC-ICP-MS mineral separates, SIMS intracrystalline isotope profiles, and DFT phonon density-of-states calculations constrain reduced partition function ratio $10^3 \ln \beta \approx A \langle F \rangle / T^2$ versus diffusive flux fractionation $D_2 / D_1 = (m_1 / m_2)^{\beta_{\mathrm{diff}}}$ to... | geochemistry_mineralogy_petrology_earth_materials | 3 | Geochemistry, Mineralogy, Petrology, and Earth Materials | isotope_geochemistry_geochronology | 1 | [
"mechanism"
] | [
"continental_crust",
"lithosphere"
] | [
"crystalline_rock",
"rock"
] | [
"metamorphic_transformation",
"chemical_weathering"
] | core_to_outcrop | Crustal and Mantle Geochemical Reservoirs | geological_deep_time | Cenozoic | [
"MC-ICP-MS, SIMS, and TIMS high-precision radiogenic and non-traditional stable isotope ratios",
"ab-initio density-functional-theory (DFT) vibrational force constants and diffusion profiles"
] | [
"closure temperatures, radiation-damage annealing kinetics, and crustal residence timescales"
] | [
"Urey-Bigeleisen-Mayer equilibrium fractionation $10^3 \\ln \\alpha_{A-B} \\approx A \\Delta \\langle F \\rangle / T^2$ vs. kinetic/diffusive fractionation $(m_1/m_2)^\\beta$",
"Dodson diffusive closure temperature $T_c = E_a / [R \\ln(A \\tau D_0 / a^2)]$ modified by alpha-recoil damage fraction $f_a$"
] | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q3j); corroborated across Gu et al. (2025) and Han et al. (2025). Remains open due to coupled thermal diffusion, metamorphic recrystallization, and redox phase partitioning and crystal lattice defect density, cooling rate, and open- vs. c... | Co-located observations of MC-ICP-MS, SIMS, and TIMS high-precision radiogenic and non-traditional stable isotope ratios and ab-initio density-functional-theory (DFT) vibrational force constants and diffusion profiles across Crustal and Mantle Geochemical Reservoirs coupled with process-resolving models of metamorphic ... | open | framework_dependent | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-002662",
"UEARTH-002926",
"UEARTH-000270"
] | [
"10.17226/25761",
"10.1021/acs.est.4c09103",
"10.1093/pnasnexus/pgaf061",
"10.6075/J0W66J9H"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Isotope Geochemistry (EiT-Q3j), DOI:10.17226/25761",
"Gu et al. (2025), Environmental science & technology, DOI:10.1021/acs.est.4c09103",
"Han et al. (2025), PNAS nexus, DOI:10.1093/pnasnexus/pgaf061",
"A. A. P. Koppers and R. Coggon (Eds.) (20... |
UEARTH-000096 | 96 | Radiation-Damage Annealing and Diffusive Pb Loss vs. Helium Trapping in Zircon and Apatite | What physical, chemical, and dynamical mechanisms determine how alpha-recoil lattice metamictization creates percolating fast-diffusion pathways for radiogenic $\mathrm{Pb}$ loss while simultaneously creating high-energy damage traps that increase $(\mathrm{U\text{--}Th})/\mathrm{He}$ closure temperatures? | What natural processes determine how natural radiation damage inside zircon and apatite crystals can make lead leak out while trapping helium more tightly? | How can atom-probe tomography (APT) nanoscale Pb clustering, Raman metamictization mapping, and CA-ID-TIMS step-leaching constrain Arrhenius diffusivity $D(T, f_a) = (1 - f_a) D_{\mathrm{cryst}}(T) + f_a D_{\mathrm{amorphous}}(T)$ as a function of alpha dose $D_\alpha$ to resolve how alpha-recoil lattice metamictizatio... | geochemistry_mineralogy_petrology_earth_materials | 3 | Geochemistry, Mineralogy, Petrology, and Earth Materials | isotope_geochemistry_geochronology | 1 | [
"mechanism"
] | [
"continental_crust",
"lithosphere"
] | [
"crystalline_rock",
"rock"
] | [
"metamorphic_transformation",
"chemical_weathering"
] | core_to_outcrop | Crustal and Mantle Geochemical Reservoirs | geological_deep_time | Cenozoic | [
"laser-ablation ICP-MS/SIMS zircon U-Pb geochronology and Lu-Hf isotope ratios",
"broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements"
] | [
"equilibrium versus kinetic mass-dependent and mass-independent isotope fractionation factors"
] | [
"Urey-Bigeleisen-Mayer equilibrium fractionation $10^3 \\ln \\alpha_{A-B} \\approx A \\Delta \\langle F \\rangle / T^2$ vs. kinetic/diffusive fractionation $(m_1/m_2)^\\beta$",
"Dodson diffusive closure temperature $T_c = E_a / [R \\ln(A \\tau D_0 / a^2)]$ modified by alpha-recoil damage fraction $f_a$"
] | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q3k); corroborated across Shah (2025) and Griffiths et al. (2023). Remains partially solved due to coupled thermal diffusion, metamorphic recrystallization, and redox phase partitioning and crystal lattice defect density, cooling rate, an... | Co-located observations of laser-ablation ICP-MS/SIMS zircon U-Pb geochronology and Lu-Hf isotope ratios and broadband seismic tomography, receiver-function conversions, and shear-wave splitting measurements across Crustal and Mantle Geochemical Reservoirs coupled with process-resolving models of metamorphic transforma... | partially_solved | mechanism_known_magnitude_uncertain | PARTIAL-PROGRESS | true | medium | 3 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-003474",
"UEARTH-003516",
"UEARTH-000269"
] | [
"10.17226/25761",
"10.1016/j.actbio.2025.01.055",
"10.1007/s10653-022-01412-8",
"10.6075/J0W66J9H"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Geochronology (EiT-Q3k), DOI:10.17226/25761",
"Shah (2025), Acta biomaterialia, DOI:10.1016/j.actbio.2025.01.055",
"Griffiths et al. (2023), Environmental geochemistry and health, DOI:10.1007/s10653-022-01412-8",
"A. A. P. Koppers and R. Coggon... |
UEARTH-000097 | 97 | Electronic Spin-Crossover Effects of Iron in Lower-Mantle Bridgmanite and Ferropericlase | What physical, chemical, and dynamical mechanisms determine how the high-spin to low-spin electronic transition of $\mathrm{Fe}^{2+}$ and $\mathrm{Fe}^{3+}$ in ferropericlase and bridgmanite at $40\text{--}70\,\mathrm{GPa}$ alters bulk sound velocity, radiative thermal conductivity, and iron partitioning in the mid-low... | What natural processes determine how pressure squeezes iron electrons into a compact spin state deep in Earth's mantle and changes rock stiffness and heat flow? | How can laser-heated diamond-anvil cell synchrotron Mössbauer/X-ray emission spectroscopy and Brillouin elastic wave velocities constrain mixed-spin fraction $n_{\mathrm{LS}}(P, T) = [1 + g \exp(\Delta G_{\mathrm{HS\to LS}} / k_B T)]^{-1}$ softening isothermal bulk modulus $K_T$ to resolve how the high-spin to low-spin... | geochemistry_mineralogy_petrology_earth_materials | 3 | Geochemistry, Mineralogy, Petrology, and Earth Materials | high_pressure_mineral_physics_metamorphism | 1 | [
"mechanism",
"budget"
] | [
"lithosphere",
"upper_mantle"
] | [
"crystalline_rock",
"mantle_silicate"
] | [
"metamorphic_transformation",
"crustal_deformation"
] | core_to_outcrop | High-Pressure Metamorphic Terranes and Deep Lithosphere | multi_million_year_tectonic | Cenozoic | [
"synchrotron X-ray absorption spectroscopy (EXAFS/XANES) and high-resolution molecular spectroscopy",
"diamond-anvil-cell synchrotron X-ray diffraction, Brillouin scattering, and EBSD fabric analyses"
] | [
"mineral elastic moduli, seismic wave-velocity anisotropy, and dehydration embrittlement kinetics"
] | [
"Birch-Murnaghan 3rd-order equation of state $P(V) = \\frac{3}{2} K_0 [(V_0/V)^{7/3} - (V_0/V)^{5/3}] \\{1 + \\frac{3}{4}(K_0' - 4)[(V_0/V)^{2/3} - 1]\\}$",
"tectonic overpressure deviation $\\Delta P_{\\mathrm{tect}} = P_{\\mathrm{mean}} - \\rho g z$ bounded by deviatoric shear strength $\\tau_{\\mathrm{yield}}$... | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q1d); corroborated across Hsieh et al. (2025) and Ni et al. (2025). Remains open due to coupled tectonic burial/exhumation, deviatoric stress, and metamorphic fluid infiltration and bulk rock composition, grain-size evolution, and water a... | Co-located observations of synchrotron X-ray absorption spectroscopy (EXAFS/XANES) and high-resolution molecular spectroscopy and diamond-anvil-cell synchrotron X-ray diffraction, Brillouin scattering, and EBSD fabric analyses across High-Pressure Metamorphic Terranes and Deep Lithosphere coupled with process-resolving... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-000099",
"UEARTH-000100",
"UEARTH-000311"
] | [
"10.17226/25761",
"10.1038/s41467-025-65430-7",
"10.1126/sciadv.adt9106",
"10.6075/J0W66J9H"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Mineral Physics (EiT-Q1d), DOI:10.17226/25761",
"Hsieh et al. (2025), Nature communications, DOI:10.1038/s41467-025-65430-7",
"Ni et al. (2025), Science advances, DOI:10.1126/sciadv.adt9106",
"A. A. P. Koppers and R. Coggon (Eds.) (2020), Explo... |
UEARTH-000098 | 98 | Kimberlite Ascent Mechanics and Deep-Mantle $\mathrm{CO}_2\text{--}\mathrm{H}_2\mathrm{O}$ Volatile Exsolution | What physical, chemical, and dynamical mechanisms determine how dense, mantle-xenolith-laden kimberlite melts ascend from $\ge 150\text{--}250\,\mathrm{km}$ depth through cratonic lithosphere at $4\text{--}20\,\mathrm{m\,s^{-1}}$ without freezing or losing diamond cargo to graphitization? | What natural processes determine how diamond-bearing kimberlite magmas rocket upward through 200 km of cold continent in hours without stalling? | How can garnet/clinopyroxene xenocryst H-diffusion profiles, diamond dissolution kinetics, and experimental carbonate-silicate melt rheometry constrain crack-tip buoyancy-driven dike propagation speed $v \propto (\Delta \rho g / \eta)^{1/3} L^{2/3}$ accelerated by orthopyroxene assimilation $\mathrm{CO}_2$ exsolution t... | geochemistry_mineralogy_petrology_earth_materials | 3 | Geochemistry, Mineralogy, Petrology, and Earth Materials | igneous_petrology_magmatic_differentiation | 1 | [
"mechanism"
] | [
"magma_reservoir",
"continental_crust"
] | [
"magma_or_melt",
"crystalline_rock"
] | [
"magma_generation_and_ascent",
"metamorphic_transformation"
] | core_to_outcrop | Crustal and Upper-Mantle Magmatic Provinces | multi_million_year_tectonic | Cenozoic | [
"electron microprobe and LA-ICP-MS mineral/melt-inclusion major and trace element zoning",
"piston-cylinder and multi-anvil phase-equilibrium experiments and radiogenic Sr-Nd-Hf isotopes"
] | [
"degree of partial melting, crustal assimilation vs. fractional crystallization (AFC) mass balance"
] | [
"open-system assimilation-fractional crystallization (AFC) $dC_m/dF = [r/(r-1)] C_a / F - D_{\\mathrm{bulk}} C_m / F$ and oxygen fugacity $\\Delta \\mathrm{FMQ}$",
"McKenzie compaction length $\\delta_c = \\sqrt{k_\\phi (\\zeta + 4\\eta/3) / \\mu_f}$ governing melt extraction from crystal mush"
] | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q3l); corroborated across Hao et al. (2024) and Shah (2025). Remains open due to coupled decompression melting, mantle heat flux, and flux melting by slab-derived volatiles and source rock fertility, oxygen fugacity (fO2), and pressure-te... | Co-located observations of electron microprobe and LA-ICP-MS mineral/melt-inclusion major and trace element zoning and piston-cylinder and multi-anvil phase-equilibrium experiments and radiogenic Sr-Nd-Hf isotopes across Crustal and Upper-Mantle Magmatic Provinces coupled with process-resolving models of magma generati... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-002752",
"UEARTH-000103",
"UEARTH-000253"
] | [
"10.17226/25761",
"10.1126/sciadv.ado8550",
"10.1016/j.actbio.2025.01.055",
"10.6075/J0W66J9H"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Petrology (EiT-Q3l), DOI:10.17226/25761",
"Hao et al. (2024), Science advances, DOI:10.1126/sciadv.ado8550",
"Shah (2025), Acta biomaterialia, DOI:10.1016/j.actbio.2025.01.055",
"A. A. P. Koppers and R. Coggon (Eds.) (2020), Exploring Earth by ... |
UEARTH-000099 | 99 | Supercritical Geothermal Fluid Speciation and Metal-Chloride Complexation Above the Critical Point of Water | What physical, chemical, and dynamical mechanisms determine how the collapse of hydrogen bonding and dielectric constant in supercritical crustal fluids ($T \ge 400\,^\circ\mathrm{C}, P \le 200\,\mathrm{MPa}$) transforms ion pairing, silica solubility, and $\mathrm{Au\text{--}Cu\text{--}Mo}$ bisulfide/chloride comple... | What natural processes determine how water above its critical temperature and pressure dissolves and drops metals at the roots of volcanic hydrothermal systems? | How can in-situ hydrothermal diamond-anvil cell XAS/Raman spectroscopy and deep geothermal drilling (IDDP/Krafla) fluid sampling constrain Helgeson-Kirkham-Flowers (HKF) / density-model log $K(T, \rho_w)$ equation of state across the vapor-brine critical curve to resolve how the collapse of hydrogen bonding and dielect... | geochemistry_mineralogy_petrology_earth_materials | 3 | Geochemistry, Mineralogy, Petrology, and Earth Materials | high_pressure_mineral_physics_metamorphism | 1 | [
"mechanism",
"threshold"
] | [
"lithosphere",
"upper_mantle"
] | [
"crystalline_rock",
"mantle_silicate"
] | [
"metamorphic_transformation",
"crustal_deformation"
] | core_to_outcrop | High-Pressure Metamorphic Terranes and Deep Lithosphere | multi_million_year_tectonic | Cenozoic | [
"diamond-anvil-cell synchrotron X-ray diffraction, Brillouin scattering, and EBSD fabric analyses",
"pseudosection phase-equilibria thermobarometry and trace-element-in-mineral thermometers"
] | [
"mineral elastic moduli, seismic wave-velocity anisotropy, and dehydration embrittlement kinetics"
] | [
"Birch-Murnaghan 3rd-order equation of state $P(V) = \\frac{3}{2} K_0 [(V_0/V)^{7/3} - (V_0/V)^{5/3}] \\{1 + \\frac{3}{4}(K_0' - 4)[(V_0/V)^{2/3} - 1]\\}$",
"tectonic overpressure deviation $\\Delta P_{\\mathrm{tect}} = P_{\\mathrm{mean}} - \\rho g z$ bounded by deviatoric shear strength $\\tau_{\\mathrm{yield}}$... | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q3m); corroborated across Rusiecka et al. (2026) and Dutta et al. (2026). Remains open due to coupled tectonic burial/exhumation, deviatoric stress, and metamorphic fluid infiltration and bulk rock composition, grain-size evolution, and w... | Co-located observations of diamond-anvil-cell synchrotron X-ray diffraction, Brillouin scattering, and EBSD fabric analyses and pseudosection phase-equilibria thermobarometry and trace-element-in-mineral thermometers across High-Pressure Metamorphic Terranes and Deep Lithosphere coupled with process-resolving models of... | open | multiple_viable_hypotheses | OPEN-VERIFIED | true | medium | 3 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-000097",
"UEARTH-000100",
"UEARTH-000120"
] | [
"10.17226/25761",
"10.1007/s00410-026-02332-x",
"10.1016/j.gexplo.2026.108180",
"10.6075/J0W66J9H"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Geochemistry (EiT-Q3m), DOI:10.17226/25761",
"Rusiecka et al. (2026), Contributions to mineralogy and petrology. Beitrage zur Mineralogie und Petrologie, DOI:10.1007/s00410-026-02332-x",
"Dutta et al. (2026), Journal of Geochemical Exploration, D... |
UEARTH-000100 | 100 | Tectonic Overpressure versus Lithostatic Depth Interpretation in Ultra-High-Pressure (UHP) Metamorphism | What physical, chemical, and dynamical mechanisms determine whether coesite- and microdiamond-bearing continental eclogites record true subduction burial to $90\text{--}150\,\mathrm{km}$ lithostatic depth followed by rapid channel exhumation, or localized tectonic overpressure ($P \ge P_{\mathrm{litho}}$) in confined ... | What natural processes determine whether ultra-high-pressure rocks were truly dragged 120 km down into the mantle and popped back up, or squeezed at shallower depths? | How can quartz-in-garnet and zircon-in-garnet elastic Raman barometry compared against thermodynamic phase-equilibrium pseudosections constrain mean stress $P = -\sigma_{ii}/3 = \rho g z + \Delta P_{\mathrm{tect}}$ bounded by rock yield strength $\tau_{\mathrm{yield}}$ and inclusion elastic host-inclusion barometry to ... | geochemistry_mineralogy_petrology_earth_materials | 3 | Geochemistry, Mineralogy, Petrology, and Earth Materials | high_pressure_mineral_physics_metamorphism | 1 | [
"mechanism"
] | [
"lithosphere",
"upper_mantle"
] | [
"crystalline_rock",
"mantle_silicate"
] | [
"metamorphic_transformation",
"crustal_deformation"
] | core_to_outcrop | High-Pressure Metamorphic Terranes and Deep Lithosphere | multi_million_year_tectonic | Cenozoic | [
"laser-ablation ICP-MS/SIMS zircon U-Pb geochronology and Lu-Hf isotope ratios",
"diamond-anvil-cell synchrotron X-ray diffraction, Brillouin scattering, and EBSD fabric analyses"
] | [
"pressure-temperature-time-deformation (P-T-t-d) paths and dislocation vs. diffusion creep laws"
] | [
"Birch-Murnaghan 3rd-order equation of state $P(V) = \\frac{3}{2} K_0 [(V_0/V)^{7/3} - (V_0/V)^{5/3}] \\{1 + \\frac{3}{4}(K_0' - 4)[(V_0/V)^{2/3} - 1]\\}$",
"tectonic overpressure deviation $\\Delta P_{\\mathrm{tect}} = P_{\\mathrm{mean}} - \\rho g z$ bounded by deviatoric shear strength $\\tau_{\\mathrm{yield}}$... | Formulated in A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020, EiT-Q3n); corroborated across Jin et al. (2023) and Shah (2025). Remains open due to coupled tectonic burial/exhumation, deviatoric stress, and metamorphic fluid infiltration and bulk rock composition, grain-size evolution, and water activity... | Co-located observations of laser-ablation ICP-MS/SIMS zircon U-Pb geochronology and Lu-Hf isotope ratios and diamond-anvil-cell synchrotron X-ray diffraction, Brillouin scattering, and EBSD fabric analyses across High-Pressure Metamorphic Terranes and Deep Lithosphere coupled with process-resolving models of metamorphi... | open | active_debate | OPEN-VERIFIED | true | hard | 4 | 2,020 | National Academies Committee on Catalyzing Opportunities for Research in the Earth Sciences (CORES) | 2026-10-16T00:00:00 | [
"UEARTH-003076",
"UEARTH-003109",
"UEARTH-000108"
] | [
"10.17226/25761",
"10.1073/pnas.2219083120",
"10.1016/j.actbio.2025.01.055",
"10.6075/J0W66J9H"
] | [
"A Vision for NSF Earth Sciences 2020-2030: Earth in Time (2020), Metamorphic Petrology (EiT-Q3n), DOI:10.17226/25761",
"Jin et al. (2023), Proceedings of the National Academy of Sciences of the United States of America, DOI:10.1073/pnas.2219083120",
"Shah (2025), Acta biomaterialia, DOI:10.1016/j.actbio.2025.0... |
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