December 20, 1711 Tsunami: Seionaikai, Japan
A tsunami caused by a magnitude 6.7 earthquake began at Seionaikai, Japan on December 20, 1711. The water rose as high as 2 meters. Its effects were recorded at 1 place. It killed 1,000 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
Travel times
How long the first wave took to reach each part of the ocean, one line for each hour up to 24, estimated from the source and the depth of the sea.
The travel times are computed in your browser, which needs JavaScript.
- 1 to 4 hours
- 5 to 6 hours
- 7 to 14 hours
- 15 hours and more
Computed in your browser the way NOAA’s own travel time maps are: the wave travels at the square root of gravity times the depth, over NOAA’s ETOPO1 depths averaged to a 10 arc-minute grid. Checked against NOAA NCEI’s maps for 21 tsunamis over the first 24 hours, these lines fall within 10 minutes of NCEI’s at half the points compared and within 52 minutes at 9 in 10. They give when the first wave could arrive, not how high it is; bays, harbors and island chains finer than the grid can see it later. Not for use in a warning: see tsunami.gov.
The tsunami
- Date
- December 20, 1711
- Source
- Seionaikai, Japan
- Cause
- Earthquake
- Earthquake
- Magnitude 6.7
- Maximum water height
- 2 m (6.6 ft)
- Runups recorded
- 1
- Tsunami intensity (Soloviev-Imamura)
- 1
- Tsunami magnitude (Iida)
- 1
- Waters
- Ocean
- How certain
- Definite tsunami
- Source location
- 34.300° N, 134.000° E
The toll
- Deaths
- 1,000 with the earthquake or eruption that caused it
- Damage
- Severe (about $5 to $25 million) with the earthquake or eruption that caused it
- Houses destroyed
- 1,713 with the earthquake or eruption that caused it
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.
An earthquake occurred at Takamatsu, Kagawa Prefecture; 1,713 homes were destroyed; about 1,000 people died. About 30 recurrent shocks were recorded in the following 24 hours. Ten tsunami waves were observed during the day. (reference #414)
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 |
|---|---|---|---|---|---|---|---|
| Takamatsu | Japan | 6 | 2 | Eyewitness observation of water height |
More
Every tsunami in 1711The 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 384.