2008 United States National Seismic Hazard Maps
May 2008 Update
The 2008 U.S. Geological Survey (USGS) National Seismic Hazard Maps were originally released in April of 2008. In early May 2008 they were modified slightly. As of May 13, 2008, the content available for download on our website is up-to-date and the following changes are reflected in the open file report (v1.1). Please take a moment to read an important note regarding appropriate usage of this release.
- Table 1, Item F magnitude bins updated.
- Figures 34-38. Figures now correspond to their respective figure caption.
- Figure H-1 updated to show traces of the South Whidbey Island fault and differentiation of reverse/thrust faults from oblique reverse faults used in the 2008 model.
- Table H-1 identifies oblique reverse faults in the 2008 model.
- Figure J-1 replaced.
The 2008 U.S. Geological Survey (USGS) National Seismic Hazard Maps display earthquake ground motions for various probability levels across the United States and are applied in seismic provisions of building codes, insurance rate structures, risk assessments, and other public policy. This update of the maps incorporates new findings on earthquake ground shaking, faults, seismicity, and geodesy. The resulting maps are derived from seismic hazard curves calculated on a grid of sites across the United States that describe the frequency of exceeding a set of ground motions.
The USGS National Seismic Hazard Mapping Project developed these maps by incorporating information on potential earthquakes and associated ground shaking obtained from interaction in science and engineering workshops involving hundreds of participants, review by several science organizations and State surveys, and advice from two expert panels.
The new probabilistic hazard maps represent an update of the 2002 seismic hazard maps developed by Frankel and others (2002), which used the methodology developed for the 1996 version of the maps (Frankel and others, 1996). Algermissen and Perkins (1976) published the first probabilistic seismic hazard map of the United States which was updated in Algermissen and others (1990). The national seismic maps represent our assessment of the “best available science” in earthquake hazards estimation for the United States.
