Like John says, probably depends on your situation. We had an apartment in noe valley that shook every time the wind blew hard. I was never sure if it was an earthquake or the weather! We never saw any damage so renting was fine, but I don't think I would have bought it!
If you're concerned, you can always get a structural engineer to inspect. We did that before buying in the Bay Area. An expensive inspection, but the peace of mind was SO worth it!!