What happens if a Japan-sized earthquake hits California?

Sunday, March 20th, 2011

What happens if a Japan-sized earthquake hits California?

“The question is not if but when Southern California will be hit by a major earthquake — one so damaging that it will permanently change lives and livelihoods in the region,” warns the United States Geological Survey in a 2008 study. A magnitude 7.8 quake in California — Japan’s quake was 30 times more powerful — would kill at least 2,000 people and cause $200 billion in damage, the USGS estimated. Because of how the state’s many faults are structured, a quake of more than 8.0 is unlikely in much of California, geologists say.

The good news for California is that, according to the USGS forecast, there’s only a 4 percent chance of that 8.0 quake hitting in the next 30 years. The bad news is that a 6.7 quake or stronger is 99 percent likely to hit, and a 7.5+ temblor has a 46 percent shot. In far Northern California and the Pacific Northwest, the forecasts are even more dire: A one-in-ten chance of a major earthquake, 8.0 or greater, along the dangerous Cascadia subduction zone in the next 30 years. “Some day we will be having this same type of earthquake [as Japan] near our shores,” says UC San Diego geophysicist Frank Vernon.

Many of California’s newer skyscrapers conform to the state’s now-rigorous building codes — but many older structures would likely collapse into a “carpet of rubble.” Reuters also reports that California’s “hot desert winds could fan fires that quakes inevitably cause, overwhelming fire departments, even as ancient water pipelines burst, engineers and architects say.”

San Onofre and Diablo Canyon both have gravity-based backup cooling systems — in addition to emergency diesel generators — so that shouldn’t be a problem.


  1. Aretae says:

    That’s good. Diablo Canyon is effectively next door to my house.

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