December 17, 1670 Tsunami: Boso, Japan
A tsunami caused by a magnitude 6.4 earthquake began at Boso, Japan on December 17, 1670. The water rose as high as 2 meters. 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
- December 17, 1670
- Source
- Boso, Japan
- Cause
- Earthquake
- Earthquake
- Magnitude 6.4
- 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
- 35.500° N, 141.000° 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.
December 17, 1670, 35.5 N, 141 E, magnitude 6.4. Tsunami damage at Unakami County, Chiba Pref. Earthquake and tsunami. (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 |
|---|---|---|---|---|---|---|---|
| Unakami | Japan | 2 | Eyewitness observation of water height |
More
Every tsunami in 1670The 1600sTsunamis 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 307.