August 22, 1782 Tsunami: Odawara, Sagami Bay, Japan
A tsunami caused by a magnitude 7.3 earthquake and a landslide began at Odawara, Sagami Bay, Japan on August 22, 1782. Its effects were recorded at 3 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
- August 22, 1782
- Source
- Odawara, Sagami Bay, Japan
- Cause
- Earthquake and landslide
- Earthquake
- Magnitude 7.3
- Runups recorded
- 3
- Tsunami intensity (Soloviev-Imamura)
- 1
- Tsunami magnitude (Iida)
- 1
- Waters
- Ocean
- How certain
- Definite tsunami
- Source location
- 35.100° N, 139.700° E
The toll
- Deaths
- Many (about 101 to 1,000)
- Damage
- Severe (about $5 to $25 million) with the earthquake or eruption that caused it
- Houses destroyed
- 1,000 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.
August 22, 1782, 1-3 Japanese local time, 75.2 N (error?), 139.2 E, magnitude 7.3, event validity 4, tsunami magnitude 1. Hakone landslide. More than 1,000 houses destroyed. Odawara castle damaged. Awa (Boso), Rikuchu tsunami. Many people drowned. (reference #150)
August 23 (or 22), 1782, about 2:00 [local time], 35.1 N, 139.7 E, magnitude 7.3. There was a strong earthquake in the region of Tokyo and Kanagawa Prefectures. There was a landslide on Hakone Mountain. There were many aftershocks. Odawara, where there was much destruction, suffered especially heavily. Homes were damaged at Tokyo. A tsunami was observed on the coast of Kanagawa, Chiba, and Iwate Prefectures. The data on these events are contradictory. (reference #414)
August 22, 1782, 35.1 139.7 E, magnitude 7.3, Source: Sagami; Observation: Sagami, Boso, Rikuchu. (reference #79)
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 |
|---|---|---|---|---|---|---|---|
| Kanagawa Prefecture | Japan | 37 | Eyewitness observation of water height | ||||
| Boso Peninsula | Japan | 67 | Eyewitness observation of water height | ||||
| Rikuchu | Japan | 523 | Eyewitness observation of water height |
More
Every tsunami in 1782The 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 534.