Today marks the 100th anniversary of the 1906 San Francisco earthquake which hit the city at 5.12 a.m. on that day. In an earlier post, I commented on the significance of the 1906 earthquake, and recommended a book by Simon Winchester, A Crack in the Edge of the World: America and the Great California Earthquake of 1906. Winchester’s book tells the story of the “new geology” and helps us understand the cause of the earthquake (and all earthquakes), and provides a deeper understanding of the earth.

The city of San Francisco set up a web site marking the earthquake, and also held a huge gathering in the financial district.

The 7.8 magnitude earthquake literally destroyed the city, and the great fire that followed reeked devastating damage of the city for days after. The earthquake is considered one of the worst disasters to hit the U.S. with more than 3,000 people killed, more than 20,000 buildings destroyed (see image of city hall below), and it took until 1915 to re-build the city. This seems like very timely information for the rebuilding of New Orleans.

The quake was caused by a rupture (of more than 300 miles) along the San Andreas fault, the fault that separates two huge crustal plates: the North American Plate and the Pacific Plate.

These two masses of rocks rub up against each other along the San Andreas Fault, and at times, the build up of stress is released when the plates move, causing an earthquake.