Are California's Nuclear Power Plants Built to Withstand Earthquakes? - Manhattan Beach, CA Patch

Looking at the failure of three cooling systems at nuclear power reactors in Japan, and a second containment building explosion, I can’t help but wonder about the shortsightedness of building nuclear plants near an earthquake fault. The question arises, are we at risk here in Southern California?
The San Onofre Nuclear Power Plant was built to withstand a 7-magnitude earthquake, whose epicenter would be within five miles of the plant, according to Southern California Edison officials.
More problematic is the aptly named El Diablo Canyon Power Plant, about 200 miles up the coast from Manhattana Beach in Avila Beach. It’s a good place to build a power plant, except for four earthquake faults in the vicinity.
The design was considered safe enough to resist shaking from the nearby San Andreas Fault when construction began in 1968. But then a new fault was discovered in 1973 three miles off shore, the Hosgri fault.
And a few miles farther out, it had produced a 7.1-magnitude quake in 1927. Yet construction at El Diablo continued.
Tens of thousands of protestors gathered to block the plant's construction in 1979, according to reports in The Journal of American History. The plant was ultimately finished with a design intended to withstand a 7.5-magnitude earthquake. It went online in the mid-1980s.
The nuclear power plant on the coast to the north of Manhattan Beach, and the one to the south, are designed to resist a 7.5 and 7.0 quake respectively—to put this in perspective, the plants would be safe in an earthquake the size of the one that hit Haiti last year.
They would not be safe in an earthquake as big as the one that leveled San Francisco in 1906, which was a 7.8-magnitude.
Because the Richter Scale is logarithmic, each whole number represents a change in earthquake amplitude by a factor of 10, but that only tells part of the story. As an estimate of energy expended by a quake, each whole number represents about 31 times more energy than the amount released by the previous number, according to the U.S. Geological Survey.
Experts are predicting that the next earthquake on the San Andreas Fault could reach 8.1-magnitude.

Via http://manhattanbeach.patch.com/articles/are-californias-nuclear-power-plants-built-to-withstand-earthquakes-2