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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.
A debris flow recorded by a USGS Landslide Monitoring Station in the 2024 Elk Fire burn area near Dayton, Wyoming. The flow was triggered by intense rainfall during a thunderstorm on the evening of July 15, 2025.
A debris flow recorded by a USGS Landslide Monitoring Station in the 2024 Elk Fire burn area near Dayton, Wyoming. The flow was triggered by intense rainfall during a thunderstorm on the evening of July 15, 2025.
Timelapse photography of vegetation recovery following the 2020 CZU Lightning Complex in the Santa Cruz Mountains of northern California. This two-year image sequence begins four and a half months after the wildfire was contained. Time between photographs is approximately two weeks.
Timelapse photography of vegetation recovery following the 2020 CZU Lightning Complex in the Santa Cruz Mountains of northern California. This two-year image sequence begins four and a half months after the wildfire was contained. Time between photographs is approximately two weeks.
A landslide monitoring station within the footprint of the 2016 Fish Fire in the San Gabriel Mountains of southern California. The station collects surface and subsurface data to monitor and detect changes in local hillslope hydrologic conditions.
A landslide monitoring station within the footprint of the 2016 Fish Fire in the San Gabriel Mountains of southern California. The station collects surface and subsurface data to monitor and detect changes in local hillslope hydrologic conditions.
Steep, rugged terrain in the area burned by the 2009 Station Fire, Angeles National Forest, California. This photo was taken approximately 14 years after the wildfire, and the vegetation has fully recovered. Note the steep slopes in the background of the image.
Steep, rugged terrain in the area burned by the 2009 Station Fire, Angeles National Forest, California. This photo was taken approximately 14 years after the wildfire, and the vegetation has fully recovered. Note the steep slopes in the background of the image.
The granitic cliffs of Yosemite Valley produce frequent rockfalls, modifying the landscape but also posing risk to park visitors. Analyses of terrestrial lidar and historical structure-from-motion photogrammetry data provide relatively precise short-term (approximately 40 years) rates of rockfall and cliff retreat.
The granitic cliffs of Yosemite Valley produce frequent rockfalls, modifying the landscape but also posing risk to park visitors. Analyses of terrestrial lidar and historical structure-from-motion photogrammetry data provide relatively precise short-term (approximately 40 years) rates of rockfall and cliff retreat.
Understanding of rockfall frequency-magnitude relationships is important for managing rockfall hazards, but characterizing these relationships is a challenging problem due to limited data, limited access, and the difficulty of accurately dating historic rockfalls.
Understanding of rockfall frequency-magnitude relationships is important for managing rockfall hazards, but characterizing these relationships is a challenging problem due to limited data, limited access, and the difficulty of accurately dating historic rockfalls.
The 92-mile, dead-end Denali Park Road crosses an accelerating rock glacier. Until 2014, the rock glacier would only displace the road a few tens of centimeters per year, however during the summer of 2021 the rock glacier has moved the road almost 40 cm/day.
The 92-mile, dead-end Denali Park Road crosses an accelerating rock glacier. Until 2014, the rock glacier would only displace the road a few tens of centimeters per year, however during the summer of 2021 the rock glacier has moved the road almost 40 cm/day.
Three soil moisture sensors shown before their installation in a soil pit. The sensors will form a vertical subsurface array geared to track infiltration behavior.
Three soil moisture sensors shown before their installation in a soil pit. The sensors will form a vertical subsurface array geared to track infiltration behavior.
Soil pit shown with three soil moisture sensors installed in a subsurface vertical array. The wetting and drying of the soil will be tracked over multi-annual timescales.
Soil pit shown with three soil moisture sensors installed in a subsurface vertical array. The wetting and drying of the soil will be tracked over multi-annual timescales.
A soil moisture sensor shown prior to installation in a soil pit. This kind of sensor measures the dielectric constant of the soil using capacitance and frequency domain technology.
A soil moisture sensor shown prior to installation in a soil pit. This kind of sensor measures the dielectric constant of the soil using capacitance and frequency domain technology.
Hillslopes in the 2020 Calwood Fire burn area covered by burned and partially burned trees. This photo was taken approximately 6 months after the fire.
Hillslopes in the 2020 Calwood Fire burn area covered by burned and partially burned trees. This photo was taken approximately 6 months after the fire.
This photograph of a small watershed within the 2020 Calwood Fire burn area, Boulder County, Colorado was taken 6 months following the fire. The removal of vegetation and change in soil properties make steeply burned areas susceptible to postfire debris flows.
This photograph of a small watershed within the 2020 Calwood Fire burn area, Boulder County, Colorado was taken 6 months following the fire. The removal of vegetation and change in soil properties make steeply burned areas susceptible to postfire debris flows.
Scientists installed a hillslope monitoring station following the 2020 Calwood Fire, Boulder County, Colorado. These monitoring stations help to collect data, such rainfall and soil moisture, that is used to better understand postfire debris-flow processes.
Scientists installed a hillslope monitoring station following the 2020 Calwood Fire, Boulder County, Colorado. These monitoring stations help to collect data, such rainfall and soil moisture, that is used to better understand postfire debris-flow processes.
Postfire monitoring station within the 2020 CZU Lightning Complex burn area. This photograph was taken in February 2021 approximately 4.5 months after the fire was contained.
Postfire monitoring station within the 2020 CZU Lightning Complex burn area. This photograph was taken in February 2021 approximately 4.5 months after the fire was contained.
Postfire monitoring station within the 2020 CZU Lightning Complex burn area. This photograph was taken in February 2021 approximately 4.5 months after the fire was contained.
Postfire monitoring station within the 2020 CZU Lightning Complex burn area. This photograph was taken in February 2021 approximately 4.5 months after the fire was contained.
A debris flow recorded by a USGS Landslide Monitoring Station in the 2024 Elk Fire burn area near Dayton, Wyoming. The flow was triggered by intense rainfall during a thunderstorm on the evening of July 15, 2025.
A debris flow recorded by a USGS Landslide Monitoring Station in the 2024 Elk Fire burn area near Dayton, Wyoming. The flow was triggered by intense rainfall during a thunderstorm on the evening of July 15, 2025.
Timelapse photography of vegetation recovery following the 2020 CZU Lightning Complex in the Santa Cruz Mountains of northern California. This two-year image sequence begins four and a half months after the wildfire was contained. Time between photographs is approximately two weeks.
Timelapse photography of vegetation recovery following the 2020 CZU Lightning Complex in the Santa Cruz Mountains of northern California. This two-year image sequence begins four and a half months after the wildfire was contained. Time between photographs is approximately two weeks.
A landslide monitoring station within the footprint of the 2016 Fish Fire in the San Gabriel Mountains of southern California. The station collects surface and subsurface data to monitor and detect changes in local hillslope hydrologic conditions.
A landslide monitoring station within the footprint of the 2016 Fish Fire in the San Gabriel Mountains of southern California. The station collects surface and subsurface data to monitor and detect changes in local hillslope hydrologic conditions.
Steep, rugged terrain in the area burned by the 2009 Station Fire, Angeles National Forest, California. This photo was taken approximately 14 years after the wildfire, and the vegetation has fully recovered. Note the steep slopes in the background of the image.
Steep, rugged terrain in the area burned by the 2009 Station Fire, Angeles National Forest, California. This photo was taken approximately 14 years after the wildfire, and the vegetation has fully recovered. Note the steep slopes in the background of the image.
The granitic cliffs of Yosemite Valley produce frequent rockfalls, modifying the landscape but also posing risk to park visitors. Analyses of terrestrial lidar and historical structure-from-motion photogrammetry data provide relatively precise short-term (approximately 40 years) rates of rockfall and cliff retreat.
The granitic cliffs of Yosemite Valley produce frequent rockfalls, modifying the landscape but also posing risk to park visitors. Analyses of terrestrial lidar and historical structure-from-motion photogrammetry data provide relatively precise short-term (approximately 40 years) rates of rockfall and cliff retreat.
Understanding of rockfall frequency-magnitude relationships is important for managing rockfall hazards, but characterizing these relationships is a challenging problem due to limited data, limited access, and the difficulty of accurately dating historic rockfalls.
Understanding of rockfall frequency-magnitude relationships is important for managing rockfall hazards, but characterizing these relationships is a challenging problem due to limited data, limited access, and the difficulty of accurately dating historic rockfalls.
The 92-mile, dead-end Denali Park Road crosses an accelerating rock glacier. Until 2014, the rock glacier would only displace the road a few tens of centimeters per year, however during the summer of 2021 the rock glacier has moved the road almost 40 cm/day.
The 92-mile, dead-end Denali Park Road crosses an accelerating rock glacier. Until 2014, the rock glacier would only displace the road a few tens of centimeters per year, however during the summer of 2021 the rock glacier has moved the road almost 40 cm/day.
Three soil moisture sensors shown before their installation in a soil pit. The sensors will form a vertical subsurface array geared to track infiltration behavior.
Three soil moisture sensors shown before their installation in a soil pit. The sensors will form a vertical subsurface array geared to track infiltration behavior.
Soil pit shown with three soil moisture sensors installed in a subsurface vertical array. The wetting and drying of the soil will be tracked over multi-annual timescales.
Soil pit shown with three soil moisture sensors installed in a subsurface vertical array. The wetting and drying of the soil will be tracked over multi-annual timescales.
A soil moisture sensor shown prior to installation in a soil pit. This kind of sensor measures the dielectric constant of the soil using capacitance and frequency domain technology.
A soil moisture sensor shown prior to installation in a soil pit. This kind of sensor measures the dielectric constant of the soil using capacitance and frequency domain technology.
Hillslopes in the 2020 Calwood Fire burn area covered by burned and partially burned trees. This photo was taken approximately 6 months after the fire.
Hillslopes in the 2020 Calwood Fire burn area covered by burned and partially burned trees. This photo was taken approximately 6 months after the fire.
This photograph of a small watershed within the 2020 Calwood Fire burn area, Boulder County, Colorado was taken 6 months following the fire. The removal of vegetation and change in soil properties make steeply burned areas susceptible to postfire debris flows.
This photograph of a small watershed within the 2020 Calwood Fire burn area, Boulder County, Colorado was taken 6 months following the fire. The removal of vegetation and change in soil properties make steeply burned areas susceptible to postfire debris flows.
Scientists installed a hillslope monitoring station following the 2020 Calwood Fire, Boulder County, Colorado. These monitoring stations help to collect data, such rainfall and soil moisture, that is used to better understand postfire debris-flow processes.
Scientists installed a hillslope monitoring station following the 2020 Calwood Fire, Boulder County, Colorado. These monitoring stations help to collect data, such rainfall and soil moisture, that is used to better understand postfire debris-flow processes.
Postfire monitoring station within the 2020 CZU Lightning Complex burn area. This photograph was taken in February 2021 approximately 4.5 months after the fire was contained.
Postfire monitoring station within the 2020 CZU Lightning Complex burn area. This photograph was taken in February 2021 approximately 4.5 months after the fire was contained.
Postfire monitoring station within the 2020 CZU Lightning Complex burn area. This photograph was taken in February 2021 approximately 4.5 months after the fire was contained.
Postfire monitoring station within the 2020 CZU Lightning Complex burn area. This photograph was taken in February 2021 approximately 4.5 months after the fire was contained.