The 1923 Great Kantō Earthquake killed up to 140,000 people, destroyed Tokyo and Yokohama, and reshaped Japanese urban planning and social history.
Key Facts
- Magnitude
- 8.0 Mw
- Date & Time
- 1 September 1923, 11:58:32 JST
- Estimated death toll
- 105,000–140,000 people
- People left homeless
- approximately 2.5 million people
- Epicenter distance from Tokyo
- ~100 km southwest of Tokyo
- Disaster Prevention Day
- 1 September, commemorated annually in Japan
By the Numbers
Location
Cause → Event → Consequence
A megathrust fault rupture beneath Sagami Bay triggered the initial earthquake in Kanagawa Prefecture. Strong winds from a nearby typhoon rapidly spread fires through densely populated urban areas. The event was compounded by two successive major shocks—magnitude 7.2 beneath Tokyo Bay and magnitude 7.3 in Yamanashi—occurring within minutes of the first.
At 11:58 JST on 1 September 1923, an earthquake of approximately magnitude 8.0 struck the Kantō Plain, devastating Tokyo, Yokohama, and surrounding prefectures. Fires, fueled by typhoon winds, caused the majority of casualties and destruction. Over half of Tokyo and nearly all of Yokohama were destroyed, leaving roughly 2.5 million people homeless.
Between 105,000 and 140,000 people died, and the disaster sparked widespread social unrest, including the Kantō Massacre of ethnic Koreans. The Japanese government declared martial law and launched large-scale reconstruction under Home Minister Gotō Shinpei, significantly improving urban infrastructure. The disaster prompted lasting changes in disaster preparedness and is commemorated annually as Disaster Prevention Day.
Human Cost
Each dot represents approximately 10,000 deaths. Total estimated: 105,000 (earthquake)
Range: 105,000 – 140,000