Historical tsunamis · Aug 1, 1940, 3:08 PM UTC
1940 W. Hokkaido Island tsunami
Japan
The tsunami of Aug 1, 1940, 3:08 PM UTC originated near W. Hokkaido Island (Japan).
Key facts
- Date
- Aug 1, 1940, 3:08 PM UTC
- Cause
- Earthquake
- Magnitude
- M7.5
- Depth
- 10 km
- Maximum documented water height
- 5.00 m
- Deaths
- 10
- Injuries
- 24
- Houses destroyed
- 20
- Damage
- moderate (about US$ 1–5 million)
- Observation records
- 58
- Countries affected
- 3
It was triggered by a magnitude 7.5 earthquake at a depth of 10 km.
The highest documented water height was 5.00 m (Kamenka, Russia).
58 observation sites in 3 countries are recorded.
Outside the source country, the earliest documented arrival was at Tetyukhe (Russia) after 0:34 h.
The database records 10 deaths.
Houses destroyed: 20.
Damage is estimated at moderate (about US$ 1–5 million).
Map of observation sites
58Each dot is a documented observation site; colour and size show the observed water height. The triangle marks the source.
Tsunami arrival times
Documented arrival times from the NOAA/NCEI database, showing the earliest recorded location per country. Coverage is incomplete: a country without an entry was not necessarily spared.
- 0:00 hEarthquake (origin) · Aug 1, 1940, 3:08 PM UTC
- 0:12 hJapan · Iwanaiko · 0.83 m
- 0:34 hRussia · Tetyukhe · 3.50 m
- 1:32 hNorth Korea · Najin (Rashin) · 0.13 m
11 places with a documented arrival time
Observations by country
| Country | Observation records | Maximum documented water height | Deaths | Earliest arrival |
|---|---|---|---|---|
 Russia | 6 | 5.00 m Kamenka | — | 0:34 h |
| Japan | 50 | 3.00 m Kutsugata, Rishiri Island | 10 | 0:12 h |
 North Korea | 2 | 1.00 m Najin (Rashin) | — | 1:32 h |
Highest documented water heights
15 / 58Individual documented observations for this event. Heights come from different measurement types and sources; not every location has a measured height.
| Location / station | Observed height | Distance from source | Country |
|---|---|---|---|
| Kamenka · Primorsky | 5.00 m | 279 km | Russia |
| Tetyukhe · Primorsky | 3.50 m | 294 km | Russia |
| Kutsugata, Rishiri Island · Hokkaido | 3.00 m | 170 km | Japan |
| Oshidomari · Hokkaido | 3.00 m | 179 km | Japan |
| Rishiri Island · Hokkaido | 3.00 m | 175 km | Japan |
| Tomamae · Hokkaido | 3.00 m | 172 km | Japan |
| Beutankeushi River, Rishiri Island · Hokkaido | 2.80 m | 172 km | Japan |
| Bikuni · Hokkaido | 2.70 m | 134 km | Japan |
| Irika · Hokkaido | 2.70 m | 122 km | Japan |
| Masandomari Port, Rishiri Island · Hokkaido | 2.50 m | 172 km | Japan |
| Oniwaki, Rishiri Island · Hokkaido | 2.50 m | 176 km | Japan |
| Ratadomari, Rishiri Island · Hokkaido | 2.50 m | 172 km | Japan |
| Yobetsu · Hokkaido | 2.30 m | 120 km | Japan |
| Haboroko · Hokkaido | 2.00 m | 177 km | Japan |
| Kutsukata, Rishiri Island · Hokkaido | 2.00 m | 170 km | Japan |
More tsunamis
Source: NOAA National Centers for Environmental Information (NCEI), Global Historical Tsunami Database. Confirmed events only. Deaths and damage are database estimates; older records are incomplete. Water heights come from different types of observation.