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Matthew A Thomas

Matt Thomas is a research hydrologist in the Landslide Hazards Program.

I am a quantitative geoscientist excited to work on societally relevant earth science and engineering problems. My research at the USGS contributes to rainfall-induced landslide and post-fire debris-flow hazard warning products designed to reduce loss of life and property.

Professional Experience

  • 2022 –             Research Hydrologist, U.S. Geological Survey, Golden, CO

  • 2017 – 2021     Mendenhall Postdoctoral Fellow, U.S. Geological Survey, Golden, CO

  • 2015 – 2017     R&D Geosciences Engineer, Sandia National Laboratories, Carlsbad, NM

  • 2014 – 2015     Postdoctoral Scholar, Stanford University, Stanford, CA   

  • 2009 – 2014    Graduate Student Researcher, Stanford University, Stanford, CA

  • 2008 – 2009    Staff Geologist, Cornerstone Earth Group, Sunnyvale, CA

Education and Certifications

  • 2014     PhD in Hydrogeology, Stanford University

  • 2014     MS in Civil and Environmental Engineering, Stanford University

  • 2008     BS in Geology, University of California Los Angeles

Science and Products

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burned mountain slope with charred trees, and two people near a landslide monitoring instrument

Calwood Fire "Heil Ranch" Landslide Monitoring Site near Boulder, CO

Wildfire can radically change a mountainous landscape such that even a modest rainstorm is capable of producing deadly and destructive flash flooding and debris flows.
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Natural Hazards Mission Area, Landslide Hazards Program
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Calwood Fire "Heil Ranch" Landslide Monitoring Site near Boulder, CO

Wildfire can radically change a mountainous landscape such that even a modest rainstorm is capable of producing deadly and destructive flash flooding and debris flows.
Learn More
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A group of people look at a projection on the wall while a man talks about what is on the image.

Landslide Hazards Seminar

The USGS Landslide Hazards Seminar is hosted by the Landslide Hazards Program on Wednesdays at 3:00 PM (MTN) via Microsoft Teams. We meet every week, except for the first and last Wed of the month. Anyone is welcome to attend. Please contact us if you would like to be notified about future meetings. You can also access recordings of past presentations by selecting the linked titles below, or...

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Landslide Hazards Seminar

The USGS Landslide Hazards Seminar is hosted by the Landslide Hazards Program on Wednesdays at 3:00 PM (MTN) via Microsoft Teams. We meet every week, except for the first and last Wed of the month. Anyone is welcome to attend. Please contact us if you would like to be notified about future meetings. You can also access recordings of past presentations by selecting the linked titles below, or...

Learn More
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mountain tops with burn scars, and landslide instrument in foreground

2021 Dixie Fire, Chips Site near Belden, CA

Wildfire can radically change a mountainous landscape such that even a modest rainstorm is capable of producing deadly and destructive flash flooding and debris flows.
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Natural Hazards Mission Area, Landslide Hazards Program
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2021 Dixie Fire, Chips Site near Belden, CA

Wildfire can radically change a mountainous landscape such that even a modest rainstorm is capable of producing deadly and destructive flash flooding and debris flows.
Learn More
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mountainous valley with burn scar in foreground and person near an instrument with a solar panel

2021 Dixie Fire, Chambers Site near Belden, CA

Wildfire can radically change a mountainous landscape such that even a modest rainstorm is capable of producing deadly and destructive flash flooding and debris flows.
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Natural Hazards Mission Area, Landslide Hazards Program
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2021 Dixie Fire, Chambers Site near Belden, CA

Wildfire can radically change a mountainous landscape such that even a modest rainstorm is capable of producing deadly and destructive flash flooding and debris flows.
Learn More

Field-verified inventory of postfire hydrologic response for the 2020 CZU Lightning Complex, River, Camel, and Dolan Fires following a 26-29 January 2021 atmospheric river storm sequence

This data release is a field-verified inventory of postfire hydrologic response for the 2020 CZU (San Mateo–Santa Cruz Unit) Lightning Complex, River Fire, Camel Fire, and Dolan Fire following a 26-29 January 2021 atmospheric river storm sequence. Postfire hydrologic response types include a) no response, b) minor response, and c) major response. A “minor” response was deemed capable of impairing
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Natural Hazards Mission Area, Landslide Hazards Program, Geologic Hazards Science Center

Field-verified inventory of postfire debris flows for the 2021 Dixie Fire following a 23-25 October 2021 atmospheric river storm and 12 June 2022 thunderstorm

Summary This data release is a field-verified inventory of postfire debris flows for the 2021 Dixie Fire following a 23-25 October 2021 atmospheric river storm and 12 June 2022 thunderstorm. The “README.txt” file describes the fields for the “Inventory.csv” file. The “Chambers” and “Chips” rain gage data referenced in the inventory are included as: “Chambers-Oct2021-Storm.csv”, “Chambers-Jun2022-S
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Geologic Hazards Science Center

Results of Hydrologic Monitoring following Hurricane Maria at sites near Toro Negro State Park and Utuado, Puerto Rico

This data release includes time-series, qualitative descriptions, and laboratory testing data from two monitoring stations installed in Puerto Rico following Hurricane Maria in 2017, which led to tens of thousands of landslides across the island (Bessette-Kirton et al., 2017). The stations were installed in July of 2018 to investigate subsurface hydrologic response to rainfall and develop a quanti
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Natural Hazards Mission Area, Landslide Hazards Program, Geologic Hazards Science Center

Infiltration data collected post-Hurricane Maria across landslide source area materials, Puerto Rico, USA

This Data Release includes information to support the characterization of surface/near-surface infiltration rates of selected landslide source area materials following Hurricane Maria across Puerto Rico, USA. The dataset includes comma-delimited measurements of field-saturated hydraulic conductivity (Kfs) collected over two field campaigns (Fall 2018 and Spring 2019) as well as laboratory-derived
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Landslide Hazards Program, Geologic Hazards Science Center
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highway and access roads in narrow canyon with river at the bottom link
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The spatial distribution of debris flows in relation to observed rainfall anomalies: Insights from the Dolan Fire, California

A range of hydrologic responses can be observed in steep, recently burned terrain, which makes predicting the spatial distribution of large debris flows challenging. Studies from rainfall-induced landslides in unburned areas show evidence of hydroclimatic tuning of landslide triggering, such that the spatial distribution of events is best predicted by the observed rainfall anomaly relative to clim
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David B. Cavagnaro, Scott W. McCoy, Matthew A. Thomas, Jaime Kostelnik, Donald N. Lindsay

Postfire hydrologic response along the central California (USA) coast: Insights for the emergency assessment of postfire debris-flow hazards

The steep, tectonically active terrain along the Central California (USA) coast is well known to produce deadly and destructive debris flows. However, the extent to which fire affects debris-flow susceptibility in this region is an open question. We documented the occurrence of postfire debris floods and flows following the landfall of a storm that delivered intense rainfall across multiple burn a
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Matthew A. Thomas, Jason W. Kean, Scott W. McCoy, Donald N. Lindsay, Jaime Kostelnik, David B. Cavagnaro, Francis K. Rengers, Amy E. East, Jonathan Schwartz, Douglas P. Smith, Brian D. Collins
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Natural Hazards Mission Area, Geologic Hazards Science Center, Geology, Minerals, Energy, and Geophysics Science Center, Pacific Coastal and Marine Science Center

The rainfall intensity-duration control of debris flows after wildfire

Increased wildfire activity in the western United States has exposed regional gaps in our understanding of postfire debris-flow generation. To address this problem, we characterized flows in an unstudied area to test the rainfall intensity-duration control of the hazard. Our rainfall measurements and field observations from the northern Sierra Nevada (California, USA) show that debris flows result
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Matthew A. Thomas, Donald N. Lindsay, David B. Cavagnaro, Jason W. Kean, Scott W. McCoy, Andrew Paul Graber
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Natural Hazards Mission Area, Landslide Hazards Program, Geologic Hazards Science Center

Postwildfire soil‐hydraulic recovery and the persistence of debris flow hazards

Deadly and destructive debris flows often follow wildfire, but understanding of changes in the hazard potential with time since fire is poor. We develop a simulation‐based framework to quantify changes in the hydrologic triggering conditions for debris flows as postwildfire infiltration properties evolve through time. Our approach produces time‐varying rainfall intensity‐duration thresholds for ru
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Matthew A. Thomas, Francis K. Rengers, Jason W. Kean, Luke A. McGuire, Dennis M. Staley, Katherine R. Barnhart, Brian A. Ebel
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Natural Hazards Mission Area, Geologic Hazards Science Center, Supplemental Appropriations for Disaster Recovery Activities, Wildland Fire Science

Hillslopes in humid-tropical climates aren’t always wet: Implications for hydrologic response and landslide initiation in Puerto Rico, USA

The devastating impacts of the widespread flooding and landsliding in Puerto Rico following the September 2017 landfall of Hurricane Maria highlight the increasingly extreme atmospheric disturbances and enhanced hazard potential in mountainous humid‐tropical climate zones. Long‐standing conceptual models for hydrologically driven hazards in Puerto Rico posit that hillslope soils remain wet through

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Matthew A. Thomas, Benjamin B. Mirus, Joel B. Smith
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Natural Hazards Mission Area, Landslide Hazards Program, Geologic Hazards Science Center, Supplemental Appropriations for Disaster Recovery Activities

Deep Learning as a tool to forecast hydrologic response for landslide-prone hillslopes

Empirical thresholds for landslide warning systems have benefitted from the incorporation of soil‐hydrologic monitoring data, but the mechanistic basis for their predictive capabilities is limited. Although physically based hydrologic models can accurately simulate changes in soil moisture and pore pressure that promote landslides, their utility is restricted by high computational costs and nonuni
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Elijah Orland, Joshua J. Roering, Matthew A. Thomas, Benjamin B. Mirus
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Natural Hazards Mission Area, National Cooperative Geologic Mapping Program, Geologic Hazards Science Center

Geometric and material variability influences stress states relevant to coastal permafrost bluff failure

Scientific knowledge and engineering tools for predicting coastal erosion are largely confined to temperate climate zones that are dominated by non-cohesive sediments. The pattern of erosion exhibited by the ice-bonded permafrost bluffs in Arctic Alaska, however, is not well explained by these tools. Investigation of the oceanographic, thermal, and mechanical processes that are relevant to permafr
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Matthew A. Thomas, Alejandro Mota, Benjamin M. Jones, R. Charles Choens, Jennifer M. Frederick, Diana L. Bull
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Natural Hazards Mission Area, Geologic Hazards Science Center

Assessing the feasibility of satellite-based thresholds for hydrologically driven landsliding

Elevated soil moisture and heavy precipitation contribute to landslides worldwide. These environmental variables are now being resolved with satellites at spatiotemporal scales that could offer new perspectives on the development of landslide warning systems. However, the application of these data to hydro-meteorological thresholds (which account for antecedent soil moisture and rainfall) first ne
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Matthew A. Thomas, Brian D. Collins, Benjamin B. Mirus
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Natural Hazards Mission Area, Geologic Hazards Science Center

Landslides triggered by Hurricane Maria: Assessment of an extreme event in Puerto Rico

Hurricane Maria hit the island of Puerto Rico on 20 September 2017 and triggered more than 40,000 landslides in at least three-fourths of Puerto Rico’s 78 municipalities. The number of landslides that occurred during this event was two orders of magnitude greater than those reported from previous hurricanes. Landslide source areas were commonly limited to surficial soils but also extended into und

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Erin Bessette-Kirton, Corina Cerovski-Darriau, William Schulz, Jeffrey A. Coe, Jason W. Kean, Jonathan W. Godt, Matthew A. Thomas, K. Stephen Hughes
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Natural Hazards Mission Area, Landslide Hazards Program, National Cooperative Geologic Mapping Program, Geologic Hazards Science Center, Geosciences and Environmental Change Science Center, Supplemental Appropriations for Disaster Recovery Activities, Hurricane Maria, Hurricanes

A decade of remotely sensed observations highlight complex processes linked to coastal permafrost bluff erosion in the Arctic

Eroding permafrost coasts are indicators and integrators of changes in the Arctic System as they are susceptible to the combined effects of declining sea ice extent, increases in open water duration, more frequent and impactful storms, sea-level rise, and warming permafrost. However, few observation sites in the Arctic have yet to link decadal-scale erosion rates with changing environmental condit
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Benjamin M. Jones, Louise M. Farquharson, Carson Baughman, Richard M. Buzard, Christopher D. Arp, Guido Grosse, Diana L. Bull, Frank Günther, Ingmar Nitze, Frank Urban, Jeremy L. Kasper, Jennifer M. Frederick, Matthew A. Thomas, Craig Jones, Alejandro Mota, Scott Dallimore, Craig E. Tweedie, Christopher V. Maio, Daniel H. Mann, Bruce M. Richmond, Ann E. Gibbs, Ming Xiao, Torsten Sachs, Go Iwahana, Mikhail Z. Kanevskiy, Vladimir E. Romanovsky
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Alaska Science Center, Geosciences and Environmental Change Science Center

Identifying physics‐based thresholds for rainfall‐induced landsliding

Most regional landslide warning systems utilize empirically derived rainfall thresholds that are difficult to improve without recalibration to additional landslide events. To address this limitation, we explored the use of synthetic rainfall to generate thousands of possible storm patterns and coupled them with a physics‐based hydrology and slope stability model for various antecedent soil saturat
Authors
Matthew A. Thomas, Benjamin B. Mirus, Brian D. Collins
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Natural Hazards Mission Area, Landslide Hazards Program, Geologic Hazards Science Center

Variability in soil-water retention properties and implications for physics-based simulation of landslide early warning criteria

Rainfall-induced shallow landsliding is a persistent hazard to human life and property. Despite the observed connection between infiltration through the unsaturated zone and shallow landslide initiation, there is considerable uncertainty in how estimates of unsaturated soil-water retention properties affect slope stability assessment. This source of uncertainty is critical to evaluating the utilit
Authors
Matthew A. Thomas, Benjamin B. Mirus, Brian D. Collins, Ning Lu, Jonathan W. Godt
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Natural Hazards Mission Area, Landslide Hazards Program, Geologic Hazards Science Center

Non-USGS Publications**

Thomas MA, Kuhlman KL, & Ward AL (2017) Anthropogenic influences on groundwater in the vicinity of a long-lived radioactive waste repository. Hydrological Processes. https://doi.org/10.1002/hyp.11214
Frederick JM, Thomas MA, Bull D, Jones CA, & Roberts JD (2016) The Arctic coastal erosion problem. SAND Technical Report Series. https://doi.org/10.2172/1431492
Thomas MA & Loague K (2016) Landscape change as recorded by the Ocean Shore Railroad. Environmental and Engineering Geoscience. https://doi.org/10.2113/gseegeosci.22.3.209
Thomas MA & Kennard P (2015) Topographic and hydrologic insight for the Westside Road problem. Natural Resource Technical Report Series. https://irma.nps.gov/DataStore/Reference/Profile/2224800
Thomas MA, Loague K, & Voss CI (2015) Fluid pressure responses for a Devil's Slide-like system: problem formulation and simulation. Hydrological Processes. https://doi.org/10.1002/hyp.10267
Thomas MA & Loague K (2014) Hydrogeologic insights for a Devil's Slide-like system. Water Resources Research. https://doi.org/10.1002/2014WR015649
Pettit MM, Thomas MA, & Loague K (2014) Retreat of a coastal bluff in Pacifica, California. Environmental and Engineering Geoscience. https://doi.org/10.2113/gseegeosci.20.2.153
Thomas MA & Loague K (2014) Devil’s Slide: An evolving feature of California’s coastal landscape. Environmental and Engineering Geoscience. https://doi.org/10.2113/gseegeosci.20.1.45

**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.

Dixie Fire Post-Fire Debris Flows: A Tale of Two Storms

The Dixie fire burned steep hillslopes in the northern Sierra Nevada California during the summer of 2021. The burn area was impacted by two significant storms in October 2021 and June 2022. These storm events resulted in very different types of rainfall and very different postfire flow events. This story map uses maps, photos, and rainfall data to highlight the storms and their impacts.  

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Natural Hazards Mission Area, Landslide Hazards Program, Geologic Hazards Science Center
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Post-fire Hydrologic Response Along the Central California Coast

The Central California coast, a region characterized by active tectonics and steep terrain, is well known for producing destructive and hazardous...

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Science and Products