Why do landslides occur?
Woody material deposited by a debris-flow near the area burned by the 2020 Cameron Peak fire
Scar of Hurricane Maria landslide in volcaniclastic rocks
Yauco, Puerto Rico Landslide Monitoring Station
Landslides occur when forces that form them overcome forces resisting their formation. This can happen quickly, such as during an earthquake or rainstorm, or slowly, as happens from stream or shoreline erosion, melting of permafrost in a warming climate, or gradual weakening of hillslope materials.
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Heavy or prolonged rainfall can saturate and weaken soils and rock forming slopes, increasing the potential for a landslide.
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Earthquake shaking can weaken slope materials and cause landslides.
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Slopes that have been modified for construction can be more susceptible to landslides. Modifications that can impact slope stability includes grading for road or house building, vegetation removal, excavation or piling earth of debris, irrigation, or rerouting surface water.
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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.
Puerto Rico Landslide Monitoring Network
The USGS and the University of Puerto Rico-Mayagüez installed instruments to monitor hillslope hydrological conditions in fifteen municipalities in mountainous regions across Puerto Rico.
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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.
Puerto Rico Landslide Monitoring Network
The USGS and the University of Puerto Rico-Mayagüez installed instruments to monitor hillslope hydrological conditions in fifteen municipalities in mountainous regions across Puerto Rico.