What natural disaster devastated San Francisco in 1906?

The natural disaster that devastated San Francisco in 1906 was an earthquake.

The earthquake struck at 5:12 a.m. on April 18, 1906, along California’s San Andreas Fault. Its estimated moment magnitude was 7.9, and intense shaking lasted roughly 42 seconds. The rupture extended for about 296 miles, affecting much of Northern California.

San Francisco’s destruction was made worse by fires that erupted soon afterward and burned for several days. More than 3,000 people died according to the city’s later official estimate, while roughly 227,000 to 300,000 people were left homeless. More than 80% of the city was destroyed by the combined earthquake and fires.

A common mix-up is to describe the disaster simply as a fire, because flames caused much of the visible damage. However, the earthquake triggered the fires and remains the defining event. The disaster also helped establish the San Andreas Fault as one of the world’s most famous earthquake hazards.