Earth Science seminars

Rain falling on existing snow can produce ice layers that persist until spring, threatening transport, wildlife and power infrastructure in Alaska. Sparse observations and mountainous terrain make these events difficult to characterize. Tricia Hutton presents an analysis using high-resolution reanalysis for winters from 1950 through 2022 to determine their distribution and timing. Most events occur in November and December, with coastal areas experiencing more frequent events and larger rainfall accumulations than the interior. The analysis identifies a seasonal shift toward more December events, increasing the formation of persistent thick ice. These findings inform planning for community safety, infrastructure and ecosystems under a changing climate.

Christopher R. German examines how hydrothermal circulation affects basin-scale ocean biogeochemical cycles. Early global surveys preceded the discovery of seafloor vents, and hydrothermal inputs were long considered minor and local. GEOTRACES sections and subsequent process studies have transformed that view; the presentation traces how those observations changed understanding of trace-element and isotope cycling. Laura Moore discusses the biogeochemical consequences of widespread low-temperature hydrothermal flow, highlighting advances in detection and the distinctive effects of these systems on the water column. Lise Artigue moderates this sixth seminar of the 2026 GEOTRACES online series. Attend online via the GEOTRACES recurring public Zoom meeting. The seminar begins at 15:00 CET.

Frank Paul presents early findings from the Karakoram Anomaly Cross-ECV project. The research combines satellite Earth observations with climate data to improve glacier mass-balance modelling in a region where measurements are sparse and glaciers are changing rapidly. The talk examines how these complementary records can help monitor Karakoram glacier dynamics.

Atmospheric gravity waves arise from processes including flow over mountains, moist convection and geostrophic imbalance. They connect atmospheric layers, influence tropospheric jet streams and play a major dynamical role in the stratosphere and mesosphere. Yet much of their spectrum is unresolved by typical climate models, and observations provide limited constraints. Aditi Sheshadri presents research combining observations, high-resolution simulations and data-informed methods to understand their effects on climate variability and improve their representation in global models. Attend online via Zoom. The colloquium runs from 11:30 to 13:00 India Standard Time.

Satellite sea-ice concentration retrievals are commonly assimilated using a constant observational uncertainty of 0.10–0.15. This research instead estimates uncertainty within the assimilation system through an iterated Desroziers diagnostic constrained to the physical 0–1 concentration range. Two passive-microwave products and one optical product in both hemispheres show strongly state-dependent errors: roughly 0.02–0.10 near open water or complete cover, and 0.20–0.35 around half cover. Complete cover during melt remains difficult to constrain because the model rarely reproduces it. Comparisons among three collocated satellite products and published retrieval uncertainties support the pattern. The results suggest constant uncertainty overweights intermediate retrievals and underweights values near zero and one, with thin and ponded ice contributing errors beyond instrument noise.

Extreme heat affects rural communities, coastal regions and marine environments in different ways. This webinar presents NOAA-supported research that helps decision-makers target resilience measures to local conditions. Case studies address rural Vermont, Charleston and the Northeast Pacific. The speakers examine rural heat risk in relation to exposure and transportation infrastructure; resilience strategies that connect heat with flooding, water management and sea-level rise; and the drivers and subsurface characteristics of marine heatwaves in ecologically and economically important regions. The discussion connects research with practical decisions about location-specific resilience. The event forms part of NOAA’s Climate Program Office Heat Research Webinar Series, supported by NIHHIS and the Climate Variability and Predictability programme. Online via Vimeo with advance attendee registration. Live captions are available and the webinar will be recorded.

Satellite observations and models make it possible to monitor drought as it develops, but many tools describe weather conditions rather than the damage drought causes. They also miss related hazards that occur concurrently or in sequence, including heatwaves, fires, flooding and mudslides. Amir AghaKouchak presents impact-based drought monitoring that connects the hazard to physical and societal consequences such as crop losses, food availability, energy production and employment. The talk examines barriers to implementation, including incomplete impact data, limited local water-use information and weak links between impact assessment and existing monitoring systems. It argues for incorporating human dimensions alongside climate observations. Online via Webex; advance registration is required, with a joining invitation sent after registration approval. Live captions are available.

This project tests whether nearby National Weather Service METAR observations can fill missing pressure and temperature records at California's Sky Oaks Field Station, where measurements support carbon-cycle research. Linear mixed-effects models and inverse-distance interpolation combine archived observations from the Iowa Environmental Mesonet with USGS elevation data. The pressure model is statistically significant but its 1.21-millibar mean absolute error exceeds the one-millibar target. The temperature model finds no significant correlation and has a 2.60°F mean absolute error. An eddy-covariance tower was also restored to collect meteorological and gas-flux data. The work was completed through a NOAA NERTO internship mentored by Ivory Small and demonstrates both the potential and limitations of reconstructing local environmental observations.

Reducing greenhouse-gas emissions alone does not remove the excess carbon dioxide already present in the atmosphere. This talk surveys marine carbon dioxide removal approaches that use the ocean’s capacity to absorb CO₂ and explains instrumentation for evaluating their effectiveness. David Snyder describes DeepGreen Solutions’ Carbon Ocean-Based Atmospheric Linked Telemetry (COBALT) measurement system, which combines sensors on Sofar Ocean Spotter buoys and Spotter Scout autonomous surface vessels to investigate carbon-cycle processes and the atmospheric removal achieved by marine projects. The session includes questions and discussion.

The 10 New Insights in Climate Science report synthesizes influential and emerging research into ten findings relevant to decision-makers ahead of international climate negotiations. This launch examines changes in the climate system, the increasing costs and consequences of warming, and the political and economic influences on climate action. Leading scientists will explain the evidence behind the 2026/27 report and its implications for policy and research ahead of COP31. The programme introduces how the synthesis is produced, presents the ten insights, develops three perspectives on translating science into action, and concludes with audience questions.

Abyssal marine turbidites provide some of the longest and most spatially extensive records of subduction zone earthquake recurrence globally; however, correlation of these deposits over long distances and interpretation of synchronous emplacement requires both an understanding of the turbidite generating systems and precise dating. Here, we present an integrated suite of high-resolution bathymetry, subbottom profiles, and sediment cores from combined autonomous underwater vehicle, remotely operated vehicle, and ship-based studies at a key paleoseismic site in the southern Cascadia subduction zone. We demonstrate how widespread, earthquake-triggered landslides on the lower slope deposit discrete, proximal mass transport deposits (MTDs) that grade offshore into complex, interfingered abyssal turbidites, which correspond to records of megathrust earthquake history. We propose accretion and oversteepening of thrust folds on the lower slope both preconditions the slope to fail and provides a perpetual source of unstable material to fail during every earthquake cycle. Furthermore, we suggest the periodic and pervasive landsliding indicates coseismic deformation of the outer accretionary wedge during megathrust rupture.

This presentation introduces the first range-scale Deep-Seated Gravitational Slope Deformation (DSGSD) inventory in North America, focusing on the Sawatch Range of central Colorado. Through geomorphic mapping, field campaigns, and InSAR displacement analysis, we identified and characterized 39 previously unreported DSGSD. We analyzed this inventory to reveal the governing mechanisms that condition slopes for DSGSD development and to compare it with the global DSGSD inventory. Site-specific surveys of the South Mt. Massive and Mt. Jones DSGSDs result in interpretive cross sections that relate surface morphology to subsurface geological parameters and highlight how Sawatch DSGSDs form and evolve in unique ways. Furthermore, we discuss the implications of this work to the broader context of Rocky Mountain DSGSD. Widespread Deep-Seated Gravitational Slope Deformations Across the Sawatch Range, CO, Evans (2026), USGS Landslide Hazard Seminar, 09 September 2026.

The leaky barrel hillside hydrology metaphor—a straightforward “water in – water out” linear reservoir idealization originally applied to landslide studies more than 30 years ago by USGS scientists Ray Wilson and Gerry Wieczorek—remains useful despite (or maybe because of) its age and simplicity, especially for regional hazard forecasting applications potentially covering exceptionally large areas. The presentation will include a contextual overview of hindcasting (i.e., back-calculating) vs forecasting and the value of simple models for decision support, offer a new analytical solution for finite-duration rainfall pulses applied to examples from the Santa Cruz Mountains and Ohio River Valley, propose a rational expression for the originally empirical leaky barrel drainage coefficient, show how a leaky barrel model can be integrated into a factor of safety equation in a computationally efficient probabilistic approach amenable to spatially distributed (e.g., GIS-ish) applications, and finally show how the solutions used as input debris flow runout models.

Precipitation-triggered geohazards, including landslides, debris flows, flooding, erosion, and scour, present growing challenges as hydroclimatic extremes intensify. This presentation describes an integrated framework that combines physics-based probabilistic hazard modeling with holistic, multimodal monitoring to support detection, forecasting, prioritization, and management of geohazard risk. The framework incorporates InSAR, optical imagery, lidar, and field observations within a structured escalation pathway that links regional-scale screening with targeted investigation and decision support. Particular emphasis is placed on integrating monitoring and modeling into a self-improving system in which observations inform model refinement and models guide monitoring priorities. Current applications, implementation lessons, and future directions are discussed, including climate-informed forecasting and the development of scalable approaches that can be transferred across a wide range of geohazards and infrastructure settings. Towards an Integrated and Holistic Framework for Precipitation-Triggered Geohazard Risk Management, Kozacı (2026), 12 August 2026.

Hillslope mass wasting can have an outsized impact on both long-term landscape evolution and short-term hazards. Inputs of coarse sediment can shield river beds, alter local flow hydraulics, and impede fish passage. This talk focuses on the Fraser Canyon in British Columbia, a 375 km reach of the Fraser River where the 2018 Big Bar Landslide temporarily blocked the river and created a hydraulic barrier to salmon migration. I will examine the history of landsliding in the Fraser Canyon, evaluate hillslope morphology and valley connectivity to identify areas susceptible to future river-impacting landslides, and explore how mass wasting influences local river hydraulics within the canyon. These case studies indicate that boundary conditions at the upstream end of river networks affect downstream hillslopes, prompting questions of how drainage divide migration, incision into underlying bedrock, and valley widening impact landslide activity.

Landslides remain a major global hazard, with thousands of events each year posing significant impacts to human life, infrastructure, and ecosystems. While advanced constitutive models enable detailed slope-stability analyses at the single-hillslope scale, a critical gap persists in assessing landslide hazards at the community scale. Existing regional-scale models often struggle to balance physical rigor, predictive accuracy, and computational efficiency. They rely either on empirical approaches with limited physical basis or on mechanistic formulations that rely on major simplifying assumptions. This study presents CRISIS (Coupled Regional Rainfall-Induced and Seismic Slope Instability Simulations), a physics-based regional landslide prediction framework. It couples a pseudo-3D slope-stability formulation with a transient three-dimensional groundwater flow model. CRISIS operates in back-analysis and forward-prediction modes, integrating multi-scale topographic, geotechnical, hydraulic, and hydrological data. Back-analysis of both failed and stable slopes from prior events generates high-resolution spatial estimates of shear strength. These estimates are iteratively refined and used for forward prediction of landslide location, size, depth, and timing under future triggering events. Results reveal a strong geospatial connection between hillslope location and dominant failure mechanisms, emphasizing that landslide initiation is inherently geospatial and governed by coupled surface–subsurface processes. Application of the framework to Hurricane Maria in Puerto Rico, where over 70,000 landslides were triggered, demonstrates close agreement between predicted and observed landslide locations, sizes, and timing. The broader vision of this work is to advance regional characterization, assessment, and mitigation of cascading hazards through data-model integration.

A currently quiescent stratovolcano, Mount Shasta, California, still poses a significant hazard to nearby communities thanks to impactful non-eruptive debris flows that can occur throughout the year. In this work, we have built a more complete record of debris flow occurrence using monitoring campaigns and research into historical newspaper records; analyze debris flow frequency and triggering in the context of regional weather and climate patterns; and forecast the future of debris flow hazards at Mount Shasta. This topic is timely because of its relevance to the ongoing efforts to create up-to-date, usable, and relevant hazards assessments at United States Volcanoes, as well as a need expressed by local land managers for debris flow data. Ultimately, this work will not only enhance our understanding of debris flow occurrence at Mount Shasta, but will also aid stakeholders in land planning, hazard mitigation, and preparedness.

Rivers grow by moving their drainage divides. Drainage divide migration can be (1) gradual, and widely distributed, such that each stream grows headward by similar amounts, or (2) rapid, and narrowly focused, such that a single stream grows at the expense of its neighbors and carves a gorge. Do rivers share the wealth? Or is most of the water and attention grabbed by just a few? This talk describes patterns of drainage divide migration, downstream river incision, and bedrock landslide occurrence in two landscapes developed in gently-dipping sedimentary rock. First, we quantify drainage divide migration rates across a retreating escarpment within cuesta landscapes of southwestern Germany. Rates indicate that river growth is localized along mainstem rivers, which have reversed their flow direction and extended headward at rates ~10-1000 fold faster than long-term rock uplift and river incision rates. Growing mainstem rivers carve gorges into underlying stratigraphy, which includes erosionally-susceptible evaporites, marls, and swelling claystones, leading to a variety of slope failures and interesting geomorphic phenomena. Halfway across the globe, a similar story is taking shape. Rivers of northwestern Arizona are growing and connecting across a series of sedimentary basins that were previously isolated by basin and range tectonism. Rivers integrate across these basins by a combination of filling, spilling, and headward erosion. As rivers grapple across water-stressed landscapes, the winners incise deeper into diverse packages of syntectonic basin stratigraphy. Landslide inventory mapping aided by newly available aerial lidar data and 1:24000 scale geologic mapping reveals associations between landslides and incision through swelling claystones deposited in these Neogene basins. Intersections between both factors and existing infrastructure are shown. These case studies indicate that boundary conditions at the upstream end of river networks affect downstream hillslopes, prompting questions of how drainage divide migration, incision into underlying bedrock, and valley widening impact landslide activity.

Graham Ryan examines how the Soufrière Hills volcano has shaped Montserrat since the eruption began in 1995. Fatalities, displacement and economic damage were followed by continuing volcanic unrest, leaving uncertainty even after eruptive activity stopped. The same geology also offers potential resources. The lecture considers indigenous geothermal electricity that could supply the island and research with the Oxford Martin School into extracting critical metals from magma-derived fluids. It connects ongoing volcanic risk with opportunities for energy independence and a more sustainable economic base.

We investigated meteorological controls on seasonal deep-seated motion of the Barry Arm landslide, a ~500 Mm³ slope instability with tsunamigenic potential in Prince William Sound, Alaska. Using ground-based synthetic aperture radar, we identified periods of deep-seated displacement, and combined airborne ice-penetrating radar with a glacier melt model driven by local meteorological data to evaluate the role of Cascade Glacier, which covers much of the area contributing groundwater to the landslide. We show that an over-deepened section of Cascade Glacier adjacent to the most active part of the landslide likely acts as a transient reservoir that routes meltwater to the landslide and that deep-seated landslide motion initiated only when modeled glacier discharge exceeded a distinct threshold.