July 31, 1640 Earthquake: Uchiura Bay, Japan
A magnitude 6.5 earthquake struck Uchiura Bay, Japan on July 31, 1640. It killed 700 people, counting the tsunami it caused.
Map
Where it struck, with the other significant earthquakes within 200 km. Circles are sized and colored by magnitude; select one for its page.
The earthquake
- Date
- July 31, 1640
- Place
- Uchiura Bay, Japan
- Magnitude
- 6.5 (Ms)
- Tsunami
- Yes: the tsunami it caused
- Volcano
- The eruption it came with
- Epicenter
- 42.070° N, 140.680° E
- Country
- Japan
The toll
- Deaths
- 700 with its tsunami and other effects
- Damage
- Limited (under about $1 million)
- Houses destroyed
- Few (about 1 to 50); 20 with its tsunami and other effects
Where the literature gives no number, NCEI records a description on a scale of 1 to 4, printed here in its words. Damage is in millions of US dollars of the year of the event, not adjusted for inflation.
What the record says
NCEI’s account, from the sources it cites.
1640, July 31. There was a strong eruption of the Komagatake
volcano on Hokkaido Island... A tsunami was observed; the waves reached the coast of Tsugaru Strait in the regions of Hidaka and Tokachi (Hokkaido Island)... It is assumed that the tsunami was due to the falling of the ejecta into the sea, or to an earthquake which was felt simultaneously with the eruption. Imamura surmises that the epicenter of the earthquake was situated to the east of the volcano, while Musya considers that it was situated at sea near Cape Shiriya (northern tip of Honshu Island). (reference #414)
1640, July 31, 42.1 N, 140.7 E, magnitude 6.5. Volcanic eruption of Mt. Komagatake. 700 persons drowned. About 100 vessels and many houses washed
away. (reference #150)
Other significant earthquakes nearby
Within 200 km, the deadliest first.
- October 31, 1341, Jusanko, Japan
- March 8, 1766, Hirosaki, Japan
- July 12, 1993, Southeast, South Korea, Hokkaido, Russia, Japan
- March 21, 1982, Hokkaido, Urakawa, Hiroo, Japan
- May 27, 1704, N of Nosiro, Japan
- September 5, 2018, Hokkaido, Japan
- February 8, 1793, Aomori, Japan
- August 7, 1993, Japan
- May 21, 1962, Off Coast of Honshu Island, Japan
- February 9, 1834, W. Hokkaido Island, Japan
- June 21, 1983, N. Honshu Island, Japan
- March 9, 1952, Hokkaido, Japan
- June 13, 1792, W. Hokkaido Island, Japan
- December 8, 2025, Misawa, Honshu, Japan
- February 10, 1945, Sanriku, Japan
More
Significant earthquakes of 1640The 1600sRecent earthquakes near hereThis day in weather history
Sources
Significant earthquakes from NOAA’s National Centers for Environmental Information, Global Historical Hazard Database, cited as NCEI/WDS, doi:10.7289/V5PN93H7. Public domain. Read 2026-09-24. NCEI earthquake 942.