Geologic Hazards Fact Sheet

Earthquake Hazard in the Heart of the Homeland

The U.S. Geological Survey shaking-hazard maps for the United States are based on current information about the rate at which earthquakes occur in different areas and on how far strong shaking extends from earthquake sources.
Colors on this particular map show the levels of horizontal shaking that have a 1-in-50 chance of being exceeded in a 50-year period.
Shaking is expressed as a percentage of g (g is the acceleration of a falling object due to gravity).