Sign In
Skip Navigation LinksHome > CGS > Regional Geologic Hazards and Mapping Program > PSHA > California Geological Survey - Probablistic Seismic Hazards Assessment - Peak Ground Acceleration

Seismic Shaking Hazard Maps of California

Seismic shaking maps are prepared using consensus information on historical earthquakes, faults, and geologic materials. Historic earthquakes, areas damaged, the slip rates of major faults, and geologic materials were combined to calculate the shaking hazard at peak ground acceleration, spectral acceleration for 0.3-second period, and spectral acceleration for 1.0-second period. The shaking hazard maps show the level of ground motion that has 1 chance in 475 of being exceeded each year, which is equal to a 10% probability of being exceeded in 50 years.

These levels of ground shaking are used primarily for formulating building codes and for designing buildings. The maps can also be used for estimating potential economic losses and preparing for emergency response. The shaking hazard maps do not include hazards from ground deformation such as liquefaction, landslides, or surface fault ruptures. These maps are not intended for site-specific hazard analysis, but only provide a regional perspective of earthquake hazard in California. Information used in preparing the maps was developed in cooperation with the U. S. Geological Survey.

CGS has published a poster depicting the various seismic hazard maps and input information that are shown below. This poster was published as California Dept. of Conservation - California Geological Survey Map Sheet 48 (1999). The cost of the map sheet is $12.00 folded and $15.00 flat, plus $4.00 shipping and handling. You can order a copy by contacting our publications group at: (916) 445-5716 or clicking here.

Peak Ground Acceleration

Click on the image below to obtain a more detailed version of the map.

Peak Ground Acceleration

Spectral Acceleration for 0.3-second period

Spectral Acceleration for 0.1-second period