Overview of Hazards and Risk Assessments

Science Center Objects

Landslide hazard and risk assessments help people understand the dangers from landslides to their towns and cities, homes, facilities, and businesses.  Landslide hazard assessments are estimates of the probability that landslides will affect a particular area or location, typically within a given timeframe.  

Landslide risk assessments go a step further and estimate of the chance of loss resulting from landslides.  Landslide hazard and risk assessments are commonly presented in the form of maps using a color scheme to indicate the relative amount of hazard or risk. 


Post-fire debris flow hazard assessments are the most visible landslide hazard assessment performed by the USGS. These assessments are prepared at the request of land and emergency management agencies responsible for managing wildfires impacts in the conterminous states.  The assessments are presented as a series of maps and geospatial data showing the probability of debris flows and their expected volume for burned drainage basins.  Other landslide hazard assessments produced by the USGS are performed at the request of government agencies or sometimes as demonstration products from research to improve methods of hazard and risk assessment.  A recent example combined the probability of rock fall and expected travel distance to inform land-use decisions in Yosemite National Park.