Many seismologists believe that the 1906 San Francisco earthquake , which occurred on the San Andreas fault , reduced the stress on many faults in the Bay Area including the Hayward fault , creating an " earthquake shadow " : a quiescent period following a major earthquake . Since the 1906 San Andreas event there have been no moderately strong earthquakes on the Hayward fault as were seen before that earthquake . It also appears likely that this quiet period in the earthquake shadow is ending , as projected by the rate of plate motion and the stress state of other faults in the region
1906 San Francisco earthquake
1906 San Francisco earthquake
Hayward Fault Zone