Contra Costa County is subject to earthquakes from seven local faults – Greenville in the southeast, Hayward North and South in the west, Concord/Green Valley in the central north, Mount Diablo in the central south and the east, Greenville in the east, Great Valley in the northeast, San Andreas in the very northeast, and the Northern Calaveras to the central south.
The last major earthquake on any of these faults was the M 6.0 Livermore Earthquake on the Greenville fault, followed by the Great Hayward Earthquake in 1868, with an estimated magnitude of between 6.8 and 7.0. Neither of these earthquakes had epicenters within Contra Costa County. The Hayward fault has the greatest likelihood of rupturing in the next 30 years of all the faults in the Bay Area, at 31% of a magnitude 6.7 or higher. This earthquake will cause damage roads and utilities, and many homes will be uninhabitable. Contra Costa County will likely experience liquefaction from this or another major earthquake along the bay near Richmond as well as in East County along the delta.
Contra Costa County Hazard Map
Use this map to determine the most damaging earthquake scenario for your area, then click on the map to view the shaking scenario map.
Source: USGS, 2013.