May 13, 1791 Tsunami: Ryukyu Islands, Japan
A tsunami of unknown cause began at Ryukyu Islands, Japan on May 13, 1791. The water rose as high as 11 meters. Its effects were recorded at 4 places.
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
- May 13, 1791
- Source
- Ryukyu Islands, Japan
- Cause
- Unknown
- Maximum water height
- 11 m (36.1 ft)
- Runups recorded
- 4
- Tsunami intensity (Soloviev-Imamura)
- 2.5
- Tsunami magnitude (Iida)
- 2
- Waters
- Ocean
- How certain
- Questionable tsunami
- Source location
- 32.800° N, 130.300° E
The toll
- Damage
- Limited (under about $1 million)
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.
Reference #150:
Tsunami damage. No earthquake description. 1.5-11m high tide.
Reference #79:
4 harbors damaged. No quake recorded. Imamura considers distant tsunami. 11 m wave height at Naha and Osato, Ryukyu Is.
Reference #414:
1791, May 13. Validity 3. A tsunami was observed on the coast of Okinawa Island, although there are no reports of an earthquake. The water level rose 1.5 m on the average, and at Yonabaru Port, on the southeast of the island, it rose up to 11 m due to the funnel shape of the bay. Four harbors were destroyed. According to Imamura, this was a tsunami from a remote earthquake.
Iida et al. (1967): m=1.
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 |
|---|---|---|---|---|---|---|---|
| Ryukyu Island, Naha | Japan | 770 | 11 | Eyewitness observation of water height | |||
| Yonabaru Port | Japan | 772 | 11 | Eyewitness observation of water height | |||
| Okinawa | Japan | 773 | 1.5 | Eyewitness observation of water height | |||
| Ryukyu Island, Osato | Japan | 861 | 11 | Eyewitness observation of water height |
More
Every tsunami in 1791The 1700sTsunamis of JapanThis 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 557.