It's definitely possible to make nuclear plants earthquake-proof, so long as you choose a site that isn't located directly on top of a major fault like or something. The French EPR, for example, comes this way standard. Or if you want to look at really radical solutions, consider floating reactors like the ones Russia is working on:
Why on earth would we ever try to build a nuclear plant anywhere near any general area that's prone to earthquakes? There's plenty of other real estate available for any we decide to build.
You might live on an earthquake-prone island nation like Japan. Or the easiest access to cooling water may be in someplace with an earthquake risk.
Personally, I think that probably the thing to do is work on power lines that can efficiently carry vast amounts of power long distances, and build nuke plants in places that are less crazy politically than California. Reduced earthquake likelihood would be a very nice side-benefit.
(I know this thread is dead, but I figured you should get an answer anyway.)
http://finger-tree.blogspot.com/2009/11/floating-nuclear-pla...
Earthquakes are just another engineering challenge, and one that nuclear engineers have been dealing with successfully for decades now.