Report sees big San Francisco Bay Area earthquake impacts

OAKLAND, Calif. (AP) — A hypothetical magnitude 7 earthquake on the San Francisco Bay region’s notorious Hayward fault could kill hundreds, injure thousands and cause $82 billion in property damage and business losses, according to a scenario created by a coalition of experts to help residents and policymakers prepare for and reduce disaster impacts.

The “HayWired” scenario was released Wednesday, the 112th anniversary of the Great Quake of 1906 that ravaged San Francisco.

“A scientifically realistic scenario is one way to learn about a large earthquake without the people of the bay region actually living through a disaster,” said a summary of the report, which was created by the U.S. Geological Survey and numerous partners as part of a campaign by the state Seismic Safety Commission and the California Business, Consumer Services and Housing Agency.

While the magnitude 7.8 earthquake of 1906 ruptured almost 300 miles (483 kilometers) of the mighty San Andreas fault, the HayWired scenario envisions a rupture of the Hayward fault, which lurks beneath cities on the east side of San Francisco Bay and has long been considered to potentially be the greatest seismic threat to the region of 7 million people.

The scenario’s epicenter is under Oakland and the rupture extends 52 miles (84 kilometers) along the fault, north to Richmond and south to Fremont. The movement is so huge that the offset of one side of the fault to the other is as much as 6 feet (1.8 meters) and shaking could cause landslides in hills and mountains, and liquefaction of water-saturated soils around the edges of the bay.

Such a quake would be a threat to about 2 million buildings around San Francisco Bay, including 300 with foundations directly atop the fault, according to the report. Older steel-frame high-rise office buildings and newer reinforced-concrete residential buildings could be unusable for nearly a year.

All of the region’s water supply systems could be affected, especially in the East Bay, where outages could last six weeks to six months.

Just as in 1906, when thousands of buildings burned after the quake, gas and electrical fires could add to the destruction. With more fires than available firefighting equipment, and compounding problems of water shortages and traffic jams, residential and commercial space equal to 52,000 single-family homes could burn.

The scenario estimates 800 deaths, 18,000 injuries, rescue of 2,500 people from collapsed buildings and 22,000 from stalled elevators.

With damage from shaking and fire combined, an estimated 152,000 households — about 411,000 people — could be displaced.

The report contends that for a small increase in cost, construction of buildings to more stringent standards could allow 95 percent of the region’s population to remain in their homes after the envisioned earthquake.

The latest grim outlook is the second in the HayWired series and follows many studies of potential damage from the Hayward fault, which has averaged one major quake every 100 to 220 years over the past 1,900 years. Its last major quake, magnitude 6.8, occurred 150 years ago in 1868, according to the report.

“The HayWired scenario is just that — a scenario — but it’s also realistic: It could happen today,” said Glenn Pomeroy, CEO of the California Earthquake Authority, a not-for-profit provider of residential earthquake insurance. “This scenario really underscores the need to prepare, so you can recover physically and financially after the ground stops shaking.”