April 21, 1969 Tsunami: Ryukyu Islands, Japan
A tsunami caused by a magnitude 6.5 earthquake began at Ryukyu Islands, Japan on April 21, 1969 at 07:19 UTC. The water rose as high as 0.1 meters. Its effects were recorded at 6 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
- April 21, 1969, 07:19 UTC
- Source
- Ryukyu Islands, Japan
- Cause
- Earthquake
- Earthquake
- Magnitude 6.5, 41 km deep
- Maximum water height
- 0.1 m (0.3 ft)
- Runups recorded
- 6
- Tsunami intensity (Soloviev-Imamura)
- -3
- Tsunami magnitude (Iida)
- -2.3
- Waters
- Ocean
- How certain
- Definite tsunami
- Source location
- 32.200° N, 132.100° E
The toll
The record gives no deaths, injuries or damage for this tsunami.
What the record says
NCEI’s account, from the sources it cites.
April 21, 1969. 16 hr 19 min. An earthquake occurred in the Huga-Nada region of Japan and was accompanied by a tsunami.
Tsunami onsets are indecipherable in the records of the Tosashimizu and Hososlliina stations wlde tsunami-like oscillations are observable in the records of the Muroto and Kamae stations. The tsunami onset is clearly identifiable, beginning with the drop in tide ,level as recorded by the Muroto station, 42 minutes after the earthquake. (reference #417)
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 |
|---|---|---|---|---|---|---|---|
| Kamaegyoko | Japan | 68 | 0.08 | Tide gauge (half the maximum wave height) | |||
| Aburatsu | Japan | 94 | 0.05 | Tide gauge (half the maximum wave height) | |||
| Tosa-Shimizu | Japan | 103 | 0.05 | Tide gauge (half the maximum wave height) | |||
| Yawatahama | Japan | 142 | 0.05 | Tide gauge (half the maximum wave height) | |||
| Odomari | Japan | 188 | 0.06 | Tide gauge (half the maximum wave height) | |||
| Murotomisaki | Japan | 227 | 0.1 | Tide gauge (half the maximum wave height) |
More
Every tsunami in 1969The 1900sTsunamis 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 2013.