1923 Great Kantō earthquake
| 関東大地震, Kantō daijishin 関東大震災, Kantō daishinsai | |
| UTC time | 1923-09-01 02:58:32 |
|---|---|
| ISC event | 911526 |
| USGS-ANSS | ComCat |
| Local date | 1 September 1923 |
| Local time | 11:58:32 JST (UTC+09:00) |
| Duration | 4 min 48 sec |
| Magnitude | 7.9–8.2 Mw |
| Depth | 23 km (14 mi) |
| Epicenter | 35°19.6′N 139°8.3′E / 35.3267°N 139.1383°E |
| Fault | Sagami Trough |
| Type | Megathrust |
| Areas affected | Japan |
| Max. intensity | MMI XI (Extreme) JMA 7 (estimated) |
| Peak acceleration | ~ 0.41 g (est) ~ 400 gal (est) |
| Tsunami | Up to 12 m (39 ft) in Atami, Shizuoka, Tōkai |
| Landslides | Yes |
| Aftershocks | 6 of 7.0 M or higher |
| Casualties | 105,385–142,800 deaths |
The 1923 Great Kantō earthquake (関東大地震, Kantō daijishin; or 関東大震災, Kantō daishinsai) was a major earthquake that struck the Kantō Plain on the main Japanese island of Honshu at 11:58:32 JST (02:58:32 UTC) on Saturday, 1 September 1923. It had an approximate magnitude of 8.0 on the moment magnitude scale (Mw), with its epicenter located 60 km (37 mi) southwest of the capital Tokyo. The earthquake devastated Tokyo, the port city of Yokohama, and surrounding prefectures of Kanagawa, Chiba, and Shizuoka, and caused widespread damage throughout the Kantō region.
Fires, exacerbated by strong winds from a nearby typhoon, spread rapidly through the densely populated urban areas, accounting for the majority of the devastation and casualties. The death toll is estimated to have been between 105,000 and 142,000 people, including tens of thousands who went missing and were presumed dead. Over half of Tokyo and nearly all of Yokohama were destroyed, leaving approximately 2.5 million people homeless. The disaster triggered widespread social unrest, including the Kantō Massacre, in which ethnic Koreans and others mistaken for them were murdered by vigilante groups based on false rumors.
In the aftermath, the Japanese government declared martial law and undertook extensive relief and restoration efforts. The earthquake prompted ambitious plans for the reconstruction of Tokyo, aiming to create a modern, resilient imperial capital. However, these plans were often met with political contestation, financial constraints, and local resistance, leading to a reconstruction that, while significantly improving infrastructure, fell short of the grandest visions. The disaster also fueled debates about national identity, modernity, and societal values, with many commentators interpreting the event as a divine punishment for perceived moral decline and advocating for spiritual and social regeneration.
The Great Kantō earthquake remains a pivotal event in modern Japanese history, profoundly impacting urban planning, disaster preparedness, and social consciousness. 1 September is commemorated annually in Japan as Disaster Prevention Day.