Disaster

At 5:12 a.m. on April 18, 1906, the first tremors were felt on the San Andreas Fault. Just two minutes later, the quake with its epicenter in the bay 2 miles (3 kilometers) from the center of San Francisco, had shaken the city violently. A survivor described the quake as like the waves of the ocean, but swift and choppy, with a grinding noise like an enormous train. Wooden buildings crashed down, cable car tracks collapsed, and streets caved in. The gas mains burst and fires broke out and raged for four days, destroying 500 city blocks and killing more people than the quake itself, perhaps as many as 20,000 (certainly more than the 567 reported at the time by a government with keen antennae for a potential public relations disaster). Most buildings were insured against fire but not earthquakes, ay of those damaged by the quake suffered arson attacks. The city authorities took firm control, with the fire department dynamiting buildings in an attempt to keep the fire from spreading. Hundreds of looters were shot. In the end, between half and two thirds of the 400,000 population were left homeless and took to the city parks. But rebuilding took months rather than years.

New science of seismology

For the first time after such an event, pictures were seen around the world (although many were retouched to hide the scale of the destruction), and the new science of seismology had a welter of data on which to build, discovering the fault had ruptured for almost 300 miles (483 kilometers), and measuring the quake as around 7.8 on the Richter scale.