How bad was it? How did it affect you?
Twice.
The first is more of a technicality as I was two-years-old.
It was the Loma Prieta earthquake of '89:
www.vibrationdata.com/earthquakes/lomaprieta.htm
It's the second one that I remember, the 5.6 on October 30, 2007. The strongest we've had since the Loma Prieta.
http://www.mercurynews.com/2007/10/30/update-5-6-quake-hits-near-alum-rock-strongest-since-loma-prieta/
I was in college, just saving my progress of a graphic design project I'd been working on and watching my first season of American Idol.
Admittedly, I kinda freaked.