Quake study: A grim scenario

Major temblor on Hayward fault would knock out cell service, power, water for weeks

A major earthquake in California is likely to knock out many communications services for days or weeks, including the vast majority of cellphones in the areas closest to the epicenter, according to a landmark new analysis by the U.S. Geological Survey.

The widespread disruption would imperil the public’s access to 911 operators and lead to delays in reporting fires and calls for medical help.

Cell towers are vulnerable to sustained power outages. The same goes for cellular equipment on power poles and buildings at risk of extreme shaking, liquefaction and fire, the USGS said. California’s cellphone networks have been notoriously unreliable during blackouts that occur during life-threatening emergencies, such as during wildfires in 2019, where wide swaths of the San Francisco Bay Area were cut off from cell service for significant periods.

In a grim estimate of the challenges, a magnitude 7 earthquake that struck on the Bay Area’s Hayward fault could leave Alameda County — its hardest hit area — able to provide only 7% of the demand for voice and data service after the quake. That is identical to the communications service failure in New York City after the 9/11 attacks in 2001, when 93% of cellphone calls failed.

The findings in the USGS study are one of many vulnerabilities uncovered by the government agency, which formally presented its findings at a news conference Thursday.

The report comprises about 780 pages, adding to nearly 600 pages of findings released since 2018 on the so-called HayWired scenario. The report is the third volume in a series of

reports researched over six years focused on a future earthquake on the Hayward fault; the final volume was written by 20 main authors and 80 contributors.

The Hayward fault has been called a “tectonic time bomb,” and a major quake on it represents a nightmare scenario because it runs through densely populated areas with old buildings, including directly beneath the East Bay cities of Oakland, Berkeley, Hayward and Fremont.

The Hayward fault is one of California’s fastest moving, and on average, it produces a major earthquake about once every 150 to 160 years, give or take seven or

eight decades.

It has been 153 years since the last major quake — a magnitude 6.8 — on the Hayward fault. The USGS estimates a magnitude 7 quake today on that fault could result in at least 800 deaths; hundreds more could die from fire following the quake, which would make this scenario California’s deadliest since the great 1906 earthquake destroyed much of San Francisco.

In this hypothetical seismic scenario, electricity services could be out for weeks, while gas and water service could be interrupted for months. The USGS estimates an East Bay resident could be without water from six weeks to six months, and water supply outages could hobble firefighting efforts.

Transportation systems could be disrupted for years.

The USGS report said the region’s backbone commuter rail system, BART, could see its Hayward train yard heavily damaged or collapse, while train stations in Oakland, Hayward and San Leandro could be so damaged that it could take one to three years to repair them. The USGS simulations for the kind of ground shaking that could occur are far worse than for what BART was designed, meaning even some seismically retrofitted facilities at the Hayward train yard could be destroyed, the report said.

While BART’s earthquake safety program was designed to keep commuters alive during an earthquake, some sections of the

system — including parts of the East Bay — are not equipped to keep the transit service operational after a severe quake, the report said.

The USGS also identified more than 50 bridges at high risk for damage and collapse, and noted it could take three to 10 months to repair them. Many are along Interstate 880, a key artery connecting Oakland to San Jose; other freeways at risk include Interstate 680 between Fremont and Pleasanton and Interstate 580 between Oakland and Pleasanton.

With so many freeways that could potentially be damaged, “emergency response, evacuation and debris removal would be hampered and recovery ... could take longer than anticipated,” the report said. Destruction

to East Bay freeways could be so bad it may be easier to flee by heading over the bay to the west, toward San Francisco and San Mateo County.

Neighborhoods across the East Bay, such as those in Oakland, Berkeley, Richmond, Alameda, San Leandro, Hayward, Castro Valley, Union City and Pleasanton, are at risk for having more than 20% of their buildings suffer extensive damage or be destroyed. That’s a potential tipping point in which people may decide en masse to leave their homes or workplaces — even if they’re still structurally intact — because their neighborhoods have ceased to function normally.

Old buildings are a major risk. In places like Oakland, Berkeley, Hayward and Alameda,

there are many socalled soft-story apartment buildings, with flimsy first floors housing carports that can collapse in an earthquake, as well as old, vulnerable brick and brittle concrete residential buildings.

While Oakland, Berkeley and San Francisco have passed mandatory retrofit laws for soft-story apartment buildings — as have cities such as Los Angeles, Santa Monica, West Hollywood, Beverly Hills and Pasadena in Southern California — many other cities have not.

California stands to suffer $74 billion in cumulative property damage, with 1 million residential buildings and 39,000 nonresidential buildings damaged, in a major Hayward fault quake.