Working Group on California Earthquake Probabilities

California’s 35 million people live among some of the most active earthquake faults in the United States. Public safety demands credible assessments of the earthquake hazard to maintain appropriate building codes for safe construction and earthquake insurance for loss protection. Seismic hazard analysis begins with an earthquake rupture forecast—a model of probabilities that earthquakes of specified magnitudes, locations, and faulting types will occur during a specified time interval.

We combine geodetic, geologic, and seismic information to estimate frequencies of damaging earthquakes in three types of seismotectonic zones.

Because of increased public interest and concern about expected losses from future earthquakes in California, the National Earthquake Prediction Evaluation Council recommended that the probability of occurrence of large (magnitude 7 or greater) earthquakes in California be evaluated. In response to this recommendation, the U.S. Geological Survey formed the Working Group on California Earthquake Probabilities.

Comments from each of the six public hearings are available for viewing. Note that the public comment period is now closed.

Public Hearing Comments

Draft EIS

The draft EIS public comment period closed November 7, 2019. All 30,000+ comment submittals are now under review for consideration in the compilation of the final EIS.

Media & General Info

Point of Contact
John Scaggs
Tonto National Forest
john.scaggs@usda.gov

Apache Leap Special Management Area
Apache Leap SMA website