Historical tsunamis · Apr 1, 1968, 12:42 AM UTC
1968 Seikaido tsunami
Japan
The tsunami of Apr 1, 1968, 12:42 AM UTC originated near Seikaido (Japan).
Key facts
- Date
- Apr 1, 1968, 12:42 AM UTC
- Cause
- Earthquake
- Magnitude
- M7.5
- Depth
- 30 km
- Maximum documented water height
- 3.07 m
- Deaths
- 1
- Injuries
- 22
- Houses destroyed
- 4
- Damage
- moderate (about US$ 1–5 million)
- Observation records
- 61
- Countries affected
- 3
It was triggered by a magnitude 7.5 earthquake at a depth of 30 km.
The highest documented water height was 3.07 m (Urajiri, Japan).
61 observation sites in 3 countries are recorded.
The database records 1 deaths.
Houses destroyed: 4.
Damage is estimated at moderate (about US$ 1–5 million).
Map of observation sites
61Each 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) · Apr 1, 1968, 12:42 AM UTC
- 0:17 hJapan · Hososhima · 0.70 m
24 places with a documented arrival time
Observations by country
| Country | Observation records | Maximum documented water height | Deaths | Earliest arrival |
|---|---|---|---|---|
| Japan | 59 | 3.07 m Urajiri | — | 0:17 h |
 United States | 1 | 0.10 m Attu, Massacre Bay, Ak | — | — |
| USA Territory | 1 | — | — | — |
Highest documented water heights
15 / 61Individual 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 |
|---|---|---|---|
| Urajiri · Kochi | 3.07 m | 56 km | Japan |
| Komame · Kochi | 3.06 m | 57 km | Japan |
| Urashiri, Shikoku Island · Kochi | 3.00 m | 84 km | Japan |
| Fukaura · Ehime | 1.72 m | 73 km | Japan |
| Iwamizu · Ehime | 1.66 m | 73 km | Japan |
| Takenoura · Oita | 1.26 m | 84 km | Japan |
| Hososhima (Hyuga City) · Miyazaki | 1.20 m | 81 km | Japan |
| Tosa-Shimizu · Kochi | 1.16 m | 68 km | Japan |
| Sukumo · Kochi | 1.12 m | 74 km | Japan |
| Totoroko · Miyazaki | 1.01 m | 80 km | Japan |
| Hososhima (Ken) · Miyazaki | 0.99 m | 80 km | Japan |
| Kamae · Oita | 0.96 m | 77 km | Japan |
| Kitaurako · Akita | 0.75 m | 1,073 km | Japan |
| Miyanoura · Miyazaki | 0.75 m | 76 km | Japan |
| Hososhima · Miyazaki | 0.70 m | 80 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.