When did the 1906 San Francisco earthquake happen?

The great San Francisco earthquake occurred on 18 April 1906 and is commonly estimated at magnitude 7.8. The shaking and subsequent fires destroyed much of the city, killing an estimated 3,000 people. It became a landmark event in seismology and urban disaster planning because the damage was studied in extraordinary detail. The disaster also led to major changes in building codes and earthquake preparedness in the United States.