That's going to be rather awkward for California's coastal nuclear plants, which IIRC are about 80 feet above sea level. While I'm generally pro-nuclear, I've always doubted the wisdom of siting plants in earthquake-prone areas. Although the San Andreas fault in southern California is not thought to be capable of generating such a large quake, the Cascadia fault (off the coast of Washington state) probably is.<p>Plus, the fact that they're operated by PG&E fails to fill me with confidence - the company has a mediocre public safety record, and both plants were beset with construction problems: in Diablo Canyon the seismic supports for one reactor were built backwards, while one of the reactors at the San Onofre plant was also installed backwards. both plants are said to be safe for anything up to a magnitude 7 quake right next to the reactor, but hearings that were due next month to extend operating lifetime have just been postponed pending resolution of the situation in Japan.<p>The historically unusual size of the quakes at other locations around the 'ring of fire' (Chile, NZ, and now Japan) is naturally worrying to disaster planners in California, and the problems at Fukushima demonstrate the potential severity of a cascading failure. The 50 mile safety radius recommended by USG would include ~7.5 million people if applied to the San Onofre plant, which is midway between Los Angeles and San Diego, and right next to southern California's major freeway. Diablo Canyon is about 60 miles north of LA, albeit in a hilly area that is unlikely to be affected by a tsunami.