1906 San Francisco earthquake

Just after five in the morning on 18 April 1906, a great earthquake on the San Andreas Fault shook the coast of northern California, and the fires that followed burned for days through San Francisco, then the largest city on the American West Coast. More than 80 per cent of the city was destroyed and over 3,000 people are now thought to have died, making it the deadliest earthquake the United States has known. It was also one of the first great disasters recorded on photographs and film.

The shock struck at 5:12 a.m. Pacific time. A strong foreshock came some 20 to 25 seconds before the main tremor, whose violent shaking lasted around 42 seconds. The earthquake predated the Richter scale, but modern studies most often estimate its moment magnitude at 7.9, with proposals ranging from 7.7 to 8.3. The fault ruptured for hundreds of kilometres, shifting the ground by up to about six metres at the surface, and people felt the shaking from Oregon south to Los Angeles and inland into Nevada. The epicentre is now generally placed offshore, near San Francisco, though some uncertainty remains. The many small tremors of the preceding decades, once read as warnings, are now linked to seasonal loads of sediment washed into the bays by hydraulic mining during the California Gold Rush. Shaking was strongest on soft sediments and filled-in former bay land, where the ground liquefied. Santa Rosa, whose downtown was almost entirely wrecked, and San Jose also suffered heavily.

Far more destructive than the shaking were the fires. More than 30 blazes, many started by broken gas mains, burned for four days and nights. The fire chief, Dennis T. Sullivan, had been fatally injured in the earthquake. Untrained firefighters using dynamite to clear firebreaks sometimes started new fires. In all, about 25,000 buildings across 490 blocks were lost, and it has been estimated that 80 to 95 per cent of the total damage was caused by fire. Because insurers generally covered fire but not earthquakes, some owners set light to their own damaged buildings. Among the landmarks lost was the Palace Hotel, from which the visiting tenor Enrico Caruso fled clutching a signed photograph of President Theodore Roosevelt.

General Frederick Funston sent federal troops into the city on his own initiative, and over 4,000 eventually served. They patrolled against looting, guarded public buildings, helped with demolition and fed and sheltered the homeless. Mayor Eugene Schmitz authorised troops and police to shoot looters on sight, and there were also accusations of looting by soldiers. Between 227,000 and 300,000 of roughly 410,000 residents were left homeless; many crossed the bay to Oakland and Berkeley, and tent camps in Golden Gate Park and the Presidio remained in use for more than two years.

Early official counts gave 375 to over 500 deaths, but many victims, especially in Chinatown, went unrecorded, and later estimates range from 700 to more than 3,000. San Francisco's Board of Supervisors adopted the figure of over 3,000 in 2005. Property losses exceeded $400 million in the money of the time. Civic and business leaders played down the earthquake, fearing to scare off the investment the city needed, while scientists led by Andrew Lawson studied it closely; their 1908 report showed that the same fault passed close to Los Angeles.

San Francisco rebuilt rapidly on its old street plan, largely completing the work by 1915, when it hosted the Panama–Pacific International Exposition to celebrate its recovery. Plans by the planner Daniel Burnham for grand boulevards were largely set aside, though a new civic centre was built. City leaders tried to move Chinatown to the edge of the city, but its residents resisted and rebuilt it in place. The burning of City Hall and the city's records office let thousands of Chinese immigrants assert that they were residents or citizens despite the Chinese Exclusion Act. The disaster is also often said to have pushed trade, industry and population growth southward to Los Angeles.

Our 1900 and 1914 maps show the United States shortly before the earthquake and during the rebuilding of San Francisco.