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.
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.
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.
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.
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.
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.