There is a nice RAND report about the impact of a container nuke in SF (which has about the same probability of occurrence as an earthquake). Insurance turned out to be the big bugbear - which is interesting given AIG.

I'm sure such a thing would be considered a bigger shock, whereas everyone that lives there expects the quake.

We've built a system and a society that has little resilience at its heart. People aren't expecting large scale disasters, whereas simple stats should say they should prepare to cope with one every few years.

While an earthquake in San Francisco would be catastrophic, its effects on the nation would be comparatively limited relative to one in Los Angeles. Because the Port of Los Angeles is our major Pacific import/export port, 65% of all interstate truck traffic originates from the Los Angeles area. While diversion is possible, the disruption of the flow of trade would be immensely problematic. On November 13, there is going to be the largest earthquake drill in U.S. history in southern California.

Learn more here:

The Great Southern California Shakeout

Yes. The FEMA report took into account what was most likely. Apparently, they think the Big One is more likely to hit SF than LA.

The BIG one will be the Cascadia subduction zone quake centred just NW of Washington state. Forecast to be 9.75 on the richter scale, affecting Vancouver, Seattle and Portland, and it is supposed to be the most expensive natural disaster in history. Last I heard, they figured there would be a 10% chance of it happening this century.