High-Tech Quake May Shake More Than Silicon Valley

There is a major earthquake lurking in Silicon Valley's future, and when it hits, the aftershocks will be felt far beyond California.

The San Andreas Fault, which runs along the western edge of the Silicon Valley, is overdue for another major temblor. It's been quiet since the earthquake and fire that all but leveled San Francisco on April 18, 1906.

But the San Andreas is not Silicon Valley's only, or even most dangerous, earthquake hazard. The greater risk is the Hayward, which generated a magnitude 6.7 quake in 1868 directly beneath what is now the eastern edge of Silicon Valley. Back then, it leveled a few sparsely populated towns and startled the cattle.


But if the same quake happened today, the consequent destruction would dwarf the economic havoc wreaked by Hurricane Katrina.

In late 2007, the Bureau of Labor statistics estimated that a repeat of the 1868 quake would affect more than $9 billion in quarterly wages and nearly three quarters of a million jobs in the San Francisco Bay area, compared to Katrina's effect on $3 billion quarterly wages and just over 300,000 jobs.

In fact, these shocking numbers are merely conservative estimates. Risk Management Solutions, a hazard modeling consultancy based near the Hayward Fault in Newark, Calif., estimates that economic losses from an 1868 repeat would likely exceed $165 billion.

But even this is a "minimum number," according to Tom Brocher of the U.S. Geological Survey Earthquake Hazards Program and member of the 1868 Hayward Earthquake Alliance. Add in loss from fire, infrastructure damage and related business disruption, and the total could top $1.5 trillion, more than what has been spent on the Iraq War to date.

The Bay Area is aggressively mitigating its seismic risk by repairing bridges and reinforcing freeways and buildings, but there is a limit to what can be done. Most of the Bay Area's growth has occurred in a 100-year seismically quiet period following the 1906 quake, and planners have consistently underestimated the severity of the earthquake risk.

All of the Bay Area's airports and ports, and many of its highways and countless homes and businesses, are built on soft soils susceptible to shaking and subsidence, or downward shifting of structures. The Bay Area's primary water system, the Hetch-Hetchy Aqueduct, crosses several faults, including the Hayward, and terminates at a reservoir built directly atop the San Andreas Fault just south of San Francisco. In the East Bay, the Hayward Fault runs directly under fire stations, hospitals and schools, including the 30,000 student UC Berkeley campus, whose stadium is slowly being torn in two by the fault's inexorable creep.

A repeat of the 1906 or 1868 quakes will likely close most of the Bay Area's airports for days, possibly weeks. One or more of the Bay's seven major bridges will be shut down, roads and highways will be closed, water supplies disrupted, and of course thousands of homes and businesses will be damaged beyond habitability. California has the toughest seismic building codes in the country, but the codes are designed to save lives not structures. Like Katrina, the region will face a severe shortage of housing and business space that will be difficult to quickly replace.

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