‘The fault will have its revenge’: Bay Area quake reminder of East Bay fault dangers (Source latimes.com)
The earthquake that rattled the Bay Area on Thursday is another reminder of the power and danger of the Hayward Fault, which runs below the populous East Bay.
The Hayward fault, along with the San Andreas fault on the San Francisco peninsula, have long posed a twin seismic peril to the region. The San Andreas produced the devastating 1989 Loma Prieta quake and 1906 San Francisco quake. The Hayward fault could produce a magnitude 7 or greater earthquake and is directly underneath heavily populated areas. The Hayward fault courses underneath Berkeley, Oakland, Hayward and Fremont and produces a large earthquake, on average, every 160 years, with a margin of error of about 80 years. It has been 150 years since the Hayward fault last ruptured, unleashing a huge earthquake.
The Hayward fault is considered one of the nation’s most dangerous faults because it is directly under the urban centers of the East Bay, including Memorial Stadium at UC Berkeley and a now-shuttered building that formerly housed Hayward City Hall, which is slowly being torn up by fault movement. A U.S. Geological Survey scenario for a 7.0 earthquake on the Hayward fault envisions it rupturing for 52 miles from San Pablo Bay to Fremont. It would cause one side of the fault to move four feet from the other. Many buildings, including apartments, still sit directly on top of the fault line, and were built before a state law passed in 1972 prohibiting new construction or substantial renovation on top of earthquake faults. On its website, the USGS calls the Hayward fault the region’s “tectonic time bomb,” which could “cause hundreds of deaths, leave thousands homeless and devastate the region’s economy.”