The most likely fault to give in NorCal soon is the Hayward fault, I live about 13 miles from it, and it registered quakes in the 4.x range recently. The thing about the Hayward fault is this: it is very similar to the fault in Japan's Kobe earthquake (6.9), which killed 5,000, and Japan had very well engineered buildings.
Kobe shook for over 1 minute long, and the Hayward fault has done the same in the past. A repeat of the 1868 Hayward quake would devastate this area. I would really suggest that if you live in the South or Earth Bay, you get straps to hold down heavy furniture, and safety cables for stuff that's hanging, and don't put heavy shit on high up shelves.
The last time the Hayward fault burped a few months ago, it really hit home how vulnerable I am, and with two small kids, and I went out and reinforced some dangerous stuff in my house, like my hugely heavy steelcase bookshelves, and hanging 120" projection screen (75lbs). Could easily kill not only me, but my kids if it came down.