This study highlights the impacts of both high hazard and high exposure on losses caused by earthquakes in the United States. The study is based on loss estimates generated by Hazus, a geographic information system (GIS)-based earthquake loss estimation tool developed by the Federal Emergency Management Agency (FEMA). The Hazus 3.0 tool provides a method for quantifying future earthquake losses. It is national in scope, uniform in application, and comprehensive in its coverage of the built environment.
This study estimates seismic risk in select regions of the United States by using two interrelated risk indicators:
- The annualized earthquake loss (AEL), which is the estimated long-term value of earthquake losses to the general building stock in any single year in a specified geographic area (e.g., state, county, metropolitan area)
- The annualized earthquake loss ratio (AELR), which expresses estimated annualized loss as a fraction of the building inventory replacement value.
In Hazus 3.0, the total estimated economic exposure (building stock as well as content) for the nation is approximately 59 trillion USD, of which over 30% comes from California, Texas, New York, and Florida. Observations made within this report support the need for strategies to reduce the current seismic risk. Strategies to reduce future losses throughout the U.S. need to be closely integrated with policies and programs that guide urban planning and development.