Historical tsunamis · Sep 2, 1923, 2:46 AM UTC
1923 Ryukyu Islands tsunami
Japan
The tsunami of Sep 2, 1923, 2:46 AM UTC originated near Ryukyu Islands (Japan).
Key facts
- Date
- Sep 2, 1923, 2:46 AM UTC
- Cause
- Earthquake
- Magnitude
- M7.7
- Depth
- 20 km
- Maximum documented water height
- 0.30 m
- Observation records
- 6
- Countries affected
- 2
It was triggered by a magnitude 7.7 earthquake at a depth of 20 km.
The highest documented water height was 0.30 m (Sunosaki, Japan).
6 observation sites in 2 countries are recorded.
Outside the source country, the earliest documented arrival was at Tofino (Clayoquot),British Columbia (Canada) after 13:00 h.
Map of observation sites
6Each 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) · Sep 2, 1923, 2:46 AM UTC
- 13:00 hCanada · Tofino (Clayoquot),British Columbia · 0.05 m
1 places with a documented arrival time
Observations by country
| Country | Observation records | Maximum documented water height | Deaths | Earliest arrival |
|---|---|---|---|---|
| Japan | 5 | 0.30 m Sunosaki | — | — |
 Canada | 1 | 0.05 m Tofino (Clayoquot),British Columbia | — | 13:00 h |
Highest documented water heights
6 / 6Individual 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 |
|---|---|---|---|
| Sunosaki · Chiba | 0.30 m | 41 km | Japan |
| Tofino (Clayoquot),British Columbia · Bc | 0.05 m | 7,428 km | Canada |
| Atami · Shizuoka | — | 105 km | Japan |
| Ito (Itoshi) · Shizuoka | — | 101 km | Japan |
| Kamakura · Kanagawa | — | 75 km | Japan |
| Katsuura (Katsuurashi) · Chiba | — | 30 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.