Historical tsunamis · Jul 21, 1788
1788 Alaska Peninsula, Ak tsunami
United States
The tsunami of Jul 21, 1788 originated near Alaska Peninsula, Ak (United States).
Key facts
- Date
- Jul 21, 1788
- Cause
- Earthquake
- Magnitude
- M8.0
- Maximum documented water height
- 30.0 m
- Deaths
- many (about 101–1,000)
- Houses destroyed
- few (up to about 50)
- Damage
- limited (under US$ 1 million)
- Observation records
- 4
- Countries affected
- 1
It was triggered by a magnitude 8.0 earthquake.
The highest documented water height was 30.0 m (Sanak Island, Ak, United States).
4 observation sites in 1 countries are recorded.
The database records many (about 101–1,000) deaths.
Houses destroyed: few (up to about 50).
Damage is estimated at limited (under US$ 1 million).
Map of observation sites
4Each dot is a documented observation site; colour and size show the observed water height. The triangle marks the source.
Observations by country
| Country | Observation records | Maximum documented water height | Deaths | Earliest arrival |
|---|---|---|---|---|
| United States | 4 | 30.0 m Sanak Island, Ak | — | — |
Highest documented water heights
4 / 4Individual 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 |
|---|---|---|---|
| Sanak Island, Ak · Ak | 30.00 m | 673 km | United States |
| Unga Island, Ak · Ak | 30.00 m | 515 km | United States |
| Three Saints Bay, Kodiak, Ak · Ak | 10.00 m | 32 km | United States |
| Pavlof Village Alaska Peninsula, Ak · Ak | 5.00 m | 550 km | United States |
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.