October 20, 1861 Tsunami: Off Miyagi, Japan
A tsunami caused by a magnitude 7.4 earthquake began at Off Miyagi, Japan on October 20, 1861 at 17:30 UTC. The water rose as high as 3.9 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
- October 20, 1861, 17:30 UTC
- Source
- Off Miyagi, Japan
- Cause
- Earthquake
- Earthquake
- Magnitude 7.4
- Maximum water height
- 3.9 m (12.8 ft)
- Runups recorded
- 4
- Tsunami intensity (Soloviev-Imamura)
- 2
- Tsunami magnitude (Iida)
- 2
- Waters
- Ocean
- How certain
- Definite tsunami
- Source location
- 38.500° N, 142.000° E
The toll
- Damage
- Limited (under about $1 million); Moderate (about $1 to $5 million) with the earthquake or eruption that caused it
- Houses destroyed
- 70 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.
Reference #414:
On October 21, 1861, at 2:30 [local time] there was an earthquake at Hakodate, which lasted 3 1/2 minutes. A tsunami was observed on the southern part of the Sanriku coast (prefectures of Miyagi and Iwate). It caused slight
destruction. The height of the wave was 4 m at Ryori.
Reference #150:
1861, Oct, 20. 38.5 N., 142 E., magnitude 7.4. Tsunami 3.9m high at Ryori. 2 3m at Nobiru. About 70 houses destroyed by shock in area of Kitakami River. Sendai castle damage.
Reference #79:
Epicenter 37.7 N., 141.6 E
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 |
|---|---|---|---|---|---|---|---|
| Ryori | Japan | 60 | 3.9 | Eyewitness observation of water height | |||
| Nobiru | Japan | 74 | 3 | Eyewitness observation of water height | |||
| Miyagi Coast | Japan | Eyewitness observation of water height | |||||
| Iwate Coast | Japan | Eyewitness observation of water height |
More
Every tsunami in 1861The 1800sTsunamis 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 915.