What happened
At 11:58 on September 1, 1923, a magnitude-7.9 earthquake originating in Sagami Bay struck the Kanto plain. Tokyo and Yokohama were devastated mainly by fire; at the site of a former army clothing depot in Honjo, a firestorm killed tens of thousands of people in a single place. The dead and missing totaled about 105,000.
Amid false rumors, mobs — and in some cases authorities — killed thousands of Koreans, as well as Chinese and Japanese who were mistaken for Koreans.
Background
The earthquake struck at lunchtime, when cooking flames were burning across the cities, and winds at the edge of a typhoon drove the fires.
Consequences
Martial law was declared, and Goto Shinpei led an ambitious reconstruction that reshaped Tokyo. The disaster became a foundation of modern disaster planning in Japan — September 1 is now Disaster Prevention Day — and an enduring reminder of how disaster can unleash violence against minorities.