According to http://earthquake.usgs.gov,a strong 6.0 earthquake hit the San Francisco Bay Area early Sunday morning. Damage occurred to buildings in Napa, injuries have been reported, and thousands are without power. At least four aftershocks were reported and are expected to continue. An earthquake of this magnitude has not blasted the Northern California region since the 6.8 1868 Hayward Fault earthquake, the 7.8 1906 San Andreas Fault earthquake, and particularly during the 6.3 1898 Mare Island earthquake.
Even larger nearby events than the 1898 earthquake can be expected in the future. In addition, the epicentral region of this earthquake is depicted on the USGS National Seismic Hazard Maps to have a high probability of strong shaking in the future.
The earthquake is located between two major, largely strike-slip fault systems. The Hayward-Rodgers Creek Fault system, which is approximately 7 km (4 miles) west of the site, generated damaging earthquakes in 1868 and probably in 1898. Although there are several faults in the region of the earthquake, only the West Napa Fault is known to have displaced Holocene-age sediment — which is positive evidence of surface fault rupture in the last 11,000 years.
