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.
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.
Science and Products
Landslide Hazards Seminar
The USGS Landslide Hazards Seminar is a speaker series that brings together landslide researchers, academics, students, applied scientists, and others to share their work in a long format. Topics range from deep dives into numerical models to broad overviews of landslide hazards of a state. The 50-minute presentations are presented live on regular Wednesdays at 3:00 PM Mountain Time.
Postfire Landslide Monitoring Station: “Las Lomas” (2016 Fish Fire) near Duarte, California
Wildfire can increase landslide susceptibility in mountainous terrain. The USGS maintains postfire landslide monitoring stations to track hillslope hydrologic conditions in the years following fire.
Postfire Landslide Monitoring Station: “Maria Ygnacio” (2019 Cave Fire) near Santa Barbara, California
Wildfire can increase landslide susceptibility in mountainous terrain. The USGS maintains postfire landslide monitoring stations to track hillslope hydrologic conditions in the years following fire.
Dixie Fire Post-Fire Debris Flows: A Tale of Two Storms
This new geonarrative (Esri story map) highlights two storm events and their postfire impacts in the Dixie burn area.
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.
Postfire Landslide Monitoring Station: "Chips" (2021 Dixie Fire) near Belden, CA
Wildfire can increase landslide susceptibility in mountainous terrain. The USGS maintains postfire landslide monitoring stations to track hillslope hydrologic conditions in the years following fire.
Postfire Landslide Monitoring Station: "Chambers" (2021 Dixie Fire) near Belden, CA
Wildfire can increase landslide susceptibility in mountainous terrain. The USGS maintains postfire landslide monitoring stations to track hillslope hydrologic conditions in the years following fire.
Recovery in the 2020 CZU Lightning Complex burn area
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.
Rockfall, Cliff Retreat in Yosemite Valley since Last Glacial Maximum
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.
Evaluating rockfall frequency from natural slopes (multiple methods)
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.
Infrastructure on ice – when road rides on accelerating rock glacier
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.
Hillslope monitoring in the 2020 Calwood Fire burn area, Boulder County, Colorado
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 in the 2020 Calwood Fire burn area, Boulder County, Colorado
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.
Soil moisture sensor prior to installation in the 2020 Calwood Fire burn area, Boulder County, Colorado
linkA 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.
Soil moisture sensor prior to installation in the 2020 Calwood Fire burn area, Boulder County, Colorado
linkA 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.
2020 Calwood Fire burn area, Boulder County, Colorado
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.
Burned hillslopes following the 2020 Calwood 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.
Monitoring station in the 2020 Calwood Fire burn area
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.
Science and Products
Landslide Hazards Seminar
The USGS Landslide Hazards Seminar is a speaker series that brings together landslide researchers, academics, students, applied scientists, and others to share their work in a long format. Topics range from deep dives into numerical models to broad overviews of landslide hazards of a state. The 50-minute presentations are presented live on regular Wednesdays at 3:00 PM Mountain Time.
Postfire Landslide Monitoring Station: “Las Lomas” (2016 Fish Fire) near Duarte, California
Wildfire can increase landslide susceptibility in mountainous terrain. The USGS maintains postfire landslide monitoring stations to track hillslope hydrologic conditions in the years following fire.
Postfire Landslide Monitoring Station: “Maria Ygnacio” (2019 Cave Fire) near Santa Barbara, California
Wildfire can increase landslide susceptibility in mountainous terrain. The USGS maintains postfire landslide monitoring stations to track hillslope hydrologic conditions in the years following fire.
Dixie Fire Post-Fire Debris Flows: A Tale of Two Storms
This new geonarrative (Esri story map) highlights two storm events and their postfire impacts in the Dixie burn area.
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.
Postfire Landslide Monitoring Station: "Chips" (2021 Dixie Fire) near Belden, CA
Wildfire can increase landslide susceptibility in mountainous terrain. The USGS maintains postfire landslide monitoring stations to track hillslope hydrologic conditions in the years following fire.
Postfire Landslide Monitoring Station: "Chambers" (2021 Dixie Fire) near Belden, CA
Wildfire can increase landslide susceptibility in mountainous terrain. The USGS maintains postfire landslide monitoring stations to track hillslope hydrologic conditions in the years following fire.
Recovery in the 2020 CZU Lightning Complex burn area
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.
Rockfall, Cliff Retreat in Yosemite Valley since Last Glacial Maximum
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.
Evaluating rockfall frequency from natural slopes (multiple methods)
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.
Infrastructure on ice – when road rides on accelerating rock glacier
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.
Hillslope monitoring in the 2020 Calwood Fire burn area, Boulder County, Colorado
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 in the 2020 Calwood Fire burn area, Boulder County, Colorado
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.
Soil moisture sensor prior to installation in the 2020 Calwood Fire burn area, Boulder County, Colorado
linkA 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.
Soil moisture sensor prior to installation in the 2020 Calwood Fire burn area, Boulder County, Colorado
linkA 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.
2020 Calwood Fire burn area, Boulder County, Colorado
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.
Burned hillslopes following the 2020 Calwood 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.
Monitoring station in the 2020 Calwood Fire burn area
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.