A couple of weeks ago, ecib and I were driving in SF and discussing earthquakes. I asked him what he thought the chance of a major earthquake in the next 30 years was. He guessed 10%. I was surprised that an estimate is given by the USGS. For a 6.7 magnitude quake or greater in the Bay Area in the next 30 years, it is 63%. It's 99% for CA in general.