On this day in 1906 San Francisco was hit by a massive earthquake measuring 8.25 on the Richter scale.
Several books to read if you are interested in learning more about this are:
A Crack in the Edge of the World by Simon Winchester
The Great Earthquake and Firestorms of 1906 by Philip L. Fradkin
San Francisco is Burning by Dennis Smith
I am sure that there are a lot more books on the subject but these just happen to be the ones that I have read.