In total , the Bay Area is traversed by seven major fault systems with hundreds of related faults , all of which are stressed by the relative motion between the Pacific Plate and the North American Plate or by compressive stresses between these plates . The fault systems include the Hayward Fault Zone , Concord-Green Valley Fault , Calaveras Fault , Clayton-Marsh Creek-Greenville Fault , Rodgers Creek Fault , and the San Gregorio Fault . Significant blind thrust faults ( faults with near vertical motion and no surface ruptures ) are associated with portions of the Santa Cruz Mountains and the northern reaches of the Diablo Range and Mount Diablo . These " hidden " faults , which are not as well known , pose a significant earthquake hazard . Among the more well-understood faults , scientists estimate a 63 % probability of a magnitude 6.7 earthquake occurring along either the Hayward , Rogers Creek , or San Andreas fault , with an earthquake more likely to occur in the East Bay . Two of the largest earthquakes in recent history were the 1906 San Francisco earthquake and the 1989 Loma Prieta earthquake
1906 San Francisco earthquake
1906 San Francisco earthquake
San Francisco Bay Area