San Francisco earthquake of 1906 was one of the worst disasters in United States history. On April 18, 1906, an earthquake shook San Francisco, California, and caused fires that raged for three days. At least 3,000 people died in the disaster. More than half of the city’s population—about 250,000 people out of a total of 400,000—lost their homes. Most of the city, including more than 28,000 buildings, lay in ruins.
The earthquake began at 5:12 a.m. local time on April 18, 1906. Its epicenter—the point on Earth’s surface above where the earthquake originated—was on the San Andreas fault near San Francisco (see San Andreas Fault ). The earthquake lasted about 45 to 60 seconds. Scientists estimate the earthquake had a moment magnitude of 7.9. The moment magnitude scale measures the ground movements produced by an earthquake and is used especially for large earthquakes. People felt the San Francisco earthquake in southern California, as far north as Oregon, and as far east as central Nevada. That same day, many aftershocks (smaller quakes that follow a main, larger earthquake) caused further damage. One major aftershock at 8:14 a.m. destroyed many buildings that had survived the initial earthquake.
After the earthquake, fires broke out in various sections of San Francisco. These fires were caused by stoves and gas lamps that overturned, electric wires that broke, and gas mains that exploded. Firefighters could not battle the flames effectively because the city’s water mains had also been damaged. As a result, fires burned out of control for three days. The firefighters dynamited entire blocks of buildings in an attempt to stop the spreading flames. The disaster destroyed more than 4 1/2 square miles (11.7 square kilometers) of San Francisco.
After the disaster, people from across the United States raised millions of dollars and sent railroad cars loaded with goods to help the people of San Francisco. Other countries also donated money. Thousands of tradespeople poured into the city to help in the rebuilding efforts, and San Francisco quickly rose again.
Before the San Francisco earthquake, U.S. scientists knew relatively little about earthquakes and their dangers. The 1906 earthquake led to the beginning of scientific research into earthquakes in the United States.
