Alameda County Earthquake Hazard

Alameda County is subject to earthquakes from seven faults: the San Andreas fault in the southwest corner, Hayward-Rogers Creek North and South faults in the western part of the county, the Central Calaveras and the Northern Calaveras in the central county, the Mount Diablo Thrust in north central county and the northeast corner, and the Greenville fault in east county.

The last major earthquake on any of these faults was The Great Hayward Quake of October 21, 1868, with an epicenter near Hayward, was estimated to be between 6.8 and 7.0. 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. Widespread liquefaction is likely in the flatlands of the county near the Bay, while landslides are likely on hillsides.

Alameda County Hazard Map

Alameda Hayward NS Hayward S San Andreas San Andreas Calaveras SCN Greenville Mt Diablo Thrust Mt Diablo Thrust Central Calaveras
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Source: USGS, 2013.

Liquefaction Hazard Map

Source: USGS Open-File Reports 02-296 and 2008-1270
Northwestern Alameda County

The map predicts the approximate percentage of each designated area that will liquefy and show surface manifestations of liquefaction such as sand boils and ground cracking.

Last updated: 01.18.2017