March 8, 1766 Tsunami: Sanriku, Japan
A tsunami caused by a magnitude 6.9 earthquake began at Sanriku, Japan on March 8, 1766. Its effects were recorded at 3 places. It killed 1,700 people, counting the earthquake or eruption that caused it.
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
- March 8, 1766
- Source
- Sanriku, Japan
- Cause
- Earthquake
- Earthquake
- Magnitude 6.9
- Runups recorded
- 3
- Tsunami intensity (Soloviev-Imamura)
- 1
- Tsunami magnitude (Iida)
- -0.1
- Waters
- Ocean
- How certain
- Definite tsunami
- Source location
- 40.900° N, 140.700° E
The toll
- Deaths
- 1,700
- Damage
- Extreme (about $25 million or more); Severe (about $5 to $25 million) with the earthquake or eruption that caused it
- Houses destroyed
- 8,200
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.
Tsugaru, Amoroi, Chosi tsunami, 8,200 houses destroyed, 1,700 deaths. Hirosaki castle destroyed. (reference #150)
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 |
|---|---|---|---|---|---|---|---|
| Aomori | Japan | 8 | Eyewitness observation of water height | ||||
| Tsugaru | Japan | 9 | Eyewitness observation of water height | ||||
| Choshi | Japan | 572 | Eyewitness observation of water height |
More
Every tsunami in 1766The 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 487.