October 7, 1731 Tsunami: Sanriku, Japan
A tsunami caused by a magnitude 6.6 earthquake began at Sanriku, Japan on October 7, 1731. Its effects were recorded at 1 place.
Where the waves reached
The source (white) and every runup with a place, colored by the water height recorded there. A ring is a runup NCEI marks doubtful.
- Under 1 m
- 1 to 3 m
- 3 to 10 m
- 10 to 30 m
- 30 m and more
- Height not recorded
The tsunami
- Date
- October 7, 1731
- Source
- Sanriku, Japan
- Cause
- Earthquake
- Earthquake
- Magnitude 6.6
- Runups recorded
- 1
- Waters
- Ocean
- How certain
- Erroneous entry
The toll
The record gives no deaths, injuries or damage for this tsunami.
What the record says
NCEI’s account, from the sources it cites.
Reference #79:
Oct 7, 1731, 37.9 N, 140.6 E, magnitude 6.6. Observation: Japan, Iwashiro (Iwahi). Inland quake. Tsunami listing by Iida based on description of damage at river mouth by Musya, 1943, but these may have been caused by quake. Probalby no tsunami.
Reference #414:
October 7, 1731. There was a strong earthquake at Koori (Fukushima Prefecture) which caused destruction of roads, bridges and homes. The epicenter of the shock was apparently on land; its hypothetical coordinates were 37o 52' N., 140o 30' E. Imamura, Musya and others report a tsunami on the coast of Fukushima Prefecture. The assertion is based on an account of the destruction at the mouth of the river, but this destruction might also have been caused by an earthquake. There was probably no tsunami. Iida et al. (1967): 7.X; 37.9o N., 140.6o E.; M=6.6
Reference #1055:
October 7, 1731. Japan (Matsu).
Every runup
Nearest the source first. Heights are above sea level at the time; a tide gauge reads half the wave’s full height.
| Where | Country | Km from source | Water height, m | Inland, m | Measured by | First wave, UTC | Deaths |
|---|---|---|---|---|---|---|---|
| Fukushima doubtful | Japan | Eyewitness observation of water height |
More
Every tsunami in 1731The 1700sTsunamis of JapanThe earthquakeThis day in weather historyAlerts in force
Sources
Tsunami events and runups 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 tsunami event 401.