Hayward Fault Zone - Notable Earthquakes

Notable Earthquakes

The largest quake on the Hayward Fault in recorded history occurred in 1868, with an estimated magnitude of 7.0. It occurred on the southern segment of the fault, receiving its name (some decades later) from the nascent town of Hayward where it was determined the quake's epicenter was located. However, the 1868 quake caused much damage throughout the then sparsely-settled Bay Area, including the city of San Francisco. In fact, the 1868 quake became known as the "Great San Francisco Earthquake" until the larger tremor in 1906.

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.

The following table chronologically lists all of the historic earthquakes on the Hayward Fault Zone which have exceeded magnitude 5.5.

The 1868 earthquake occurred well before the East Bay region was extensively urbanized. The following year, in 1869, the William Meek Estate became one of the first developments in the area, built on 3,000 acres (12 km²) in what became known as the Cherryland district of Eden Township. Recent renovations of the Meek Mansion have revealed that with the 1868 earthquake still fresh in minds of residents of the time, some unusual diagonal bracing was built into the original construction. Although its magnitude was less than the 1906 San Francisco Earthquake, the intensity of shaking experienced in the Hayward area may have been greater than in 1906 due to the proximity of the Hayward Fault.