San Francisco Earthquake and Fire

Setting the scene

San Francisco in 1906 was America's western metropolis, rebuilt after the Gold Rush with 400,000 residents in wooden Victorian houses and brick buildings. The city straddled the San Andreas Fault, though the science of plate tectonics was decades away. Most buildings were unreinforced masonry, and the city relied on gas lighting and wooden water mains. The previous major quake in 1868 had been largely forgotten, and building codes were nonexistent. At 5:12 a.m. on April 18, the northern 296 miles of the San Andreas Fault ruptured in a magnitude 7.9 earthquake that lasted 45-60 seconds.

What happened

The shaking toppled buildings, buckled streets, and broke all water mains. But the earthquake itself killed only a few hundred. The catastrophe came from fires—broken gas lines ignited, and with no water, the fire department was helpless. The fire burned for three days, creating a firestorm that destroyed 28,000 buildings across 4.7 square miles, 80% of the city. The Army, under General Funston, dynamited buildings to create firebreaks, often spreading the flames. Refugees camped in Golden Gate Park and the Presidio. When it ended, 3,000 were dead and 250,000 homeless in a city that had been the jewel of the West.

Why it still matters

The 1906 earthquake revolutionized seismology—scientists mapped the San Andreas Fault for the first time and understood that earthquakes resulted from fault movement, not volcanic action. It led to the first earthquake-resistant building codes and the development of seismographs. The disaster also exposed corruption—insurance companies refused to pay fire claims, claiming damage was from the earthquake (not covered) rather than fire (covered). San Francisco rebuilt in three years, hosting the 1915 Panama-Pacific Exposition to prove its recovery. The quake remains California's deadliest natural disaster and established the template for modern disaster response, while reminding Americans that their cities were built on geological time bombs.

Background

Reconstruction reshaped San Francisco's urban core.