San Francisco was rocked 100 years ago today by a 7.8 magnitude quake.  As if the quake alone wasn't destructive enough, the subsequent fires destroyed the city further.  The city rebuilt itself (obviously) and was hit again in 1989 by a 7.1, causing the Bay Bridge to famously collapse and interrupting the World Series between the San Francisco Giants and Oakland A's.  Meanwhile, some scientists from my alma mater predict there is a chance the next big one could hit within 20 years.