Matthew A Thomas

The USGS Postfire Landslide Monitoring Station “Pasadena Glen” is located within the Angeles National Forest in the San Gabriel Mountains of southern California. The site consists of surface and subsurface instrumentation that is monitoring the hillslope (Photo Credit: Matthew A. Thomas, U.S. Geological survey; Public domain).

The USGS Postfire Landslide Monitoring Station “Castro Peak” is located within the Santa Monica Mountains National Recreation Area in the Santa Monica Mountains of southern California. The site consists of surface and subsurface instrumentation that is monitoring the hillslope (Photo Credit: Matthew A. Thomas, U.S. Geological survey; Public domain).

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.  

The USGS Postfire Landslide Monitoring Station “Dunsmore” is located within the Angeles National Forest in the San Gabriel Mountains of southern California. The site consists of surface and subsurface instrumentation that is monitoring the hillslope (Photo Credit: Matthew A. Thomas, U.S. Geological survey).

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 USGS Postfire Landslide Monitoring Station “Arroyo Seco” is located within the Angeles National Forest in the San Gabriel Mountains of southern California. The site consists of surface and subsurface instrumentation that is monitoring the hillslope (Photo Credit: Matthew A. Thomas, U.S. Geological survey).

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. 

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.  

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.

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.  

The effects of debris floods following the 2020 River Fire in Monterey County, California. 

Photo credit: Matthew A. Thomas, U.S. Geological Survey