Historical tsunamis · Apr 1, 1946, 12:29 PM UTC

1946 Unimak Island, Ak tsunami

United States

The tsunami of Apr 1, 1946, 12:29 PM UTC originated near Unimak Island, Ak (United States).

Key facts

Date
Apr 1, 1946, 12:29 PM UTC
Cause
Earthquake and landslide
Magnitude
M8.6
Depth
15 km
Maximum documented water height
42.0 m
Deaths
168
Houses destroyed
many (about 101–1,000)
Damage
US$ 26 million
Observation records
618
Countries affected
13

It was triggered by a magnitude 8.6 earthquake at a depth of 15 km.

The highest documented water height was 42.0 m (Scotch Cap, Ak, United States).

618 observation sites in 13 countries are recorded.

Outside the source country, the earliest documented arrival was at Tofino (Clayoquot),British Columbia (Canada) after 4:18 h.

The database records 168 deaths.

Houses destroyed: many (about 101–1,000).

Damage is estimated at US$ 26 million.

All tsunamis in United StatesRecord at NOAA/NCEI ↗

Map of observation sites

618

Each 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.

  1. 0:00 hEarthquake (origin) · Apr 1, 1946, 12:29 PM UTC
  2. 0:10 hUnited States · Sanak Island, Ak · 6.10 m
  3. 4:18 hCanada · Tofino (Clayoquot),British Columbia · 0.30 m
  4. 5:18 hJapan · Ayukawa · 0.56 m
  5. 9:14 hSamoa · Apia, Upolu Island · 1.20 m
  6. 14:30 hPeru · Talara · 0.49 m
  7. 17:21 hChile · Antofagasta · 0.90 m

39 places with a documented arrival time

Observations by country

CountryObservation recordsMaximum documented water heightDeathsEarliest arrival
United States51342.2 m
Scotch Cap, Unimak Is, Ak		1640:10 h
French Polynesia5920.0 m
Haakuti, Ua Pou, Marquesas Is.		3—
Chile68.60 m
Hanga Roa, Rapa Nui, Easter I.		—17:21 h
UK Territory15.00 m
Bounty Bay, Pitcairn Island		——
New Zealand142.40 m
Matapouri		——
Samoa21.20 m
Apia, Upolu Island		—9:14 h
USA Territory30.80 m
Pago Pago, American Samoa		——
Peru50.76 m
Matarani		114:30 h
Japan100.56 m
Ayukawa		—5:18 h
Canada20.30 m
Tofino (Clayoquot),British Columbia		—4:18 h
Australia10.08 m
Fort Denison, Sydney Harbor		——
Colombia1———
Cook Islands1———

Highest documented water heights

15 / 618

Individual documented observations for this event. Heights come from different measurement types and sources; not every location has a measured height.

Location / stationObserved heightDistance from sourceCountry
Scotch Cap, Unimak Is, Ak · Ak42.20 m161 kmUnited States
Scotch Cap, Ak · Ak42.00 m161 kmUnited States
N Cape Lutke, Unimak Is, Ak · Ak41.60 m150 kmUnited States
Scotch Cap, Unimak Is, Ak · Ak39.80 m160 kmUnited States
Unimak Island, Ak · Ak35.05 m167 kmUnited States
Promontory Hill, Unimak Is, Ak · Ak34.80 m151 kmUnited States
Seal Cape, Unimak Is, Ak · Ak27.20 m156 kmUnited States
Long Is (Northwest) · Ak24.60 m103 kmUnited States
NE Arch Point, Unimak Is, Ak · Ak23.50 m152 kmUnited States
Haakuti, Ua Pou, Marquesas Is. · Marquesas Islands20.00 m7,290 kmFrench Polynesia
Hakahau, Ua Pou, Marquesas Is. · Marquesas Islands18.90 m7,290 kmFrench Polynesia
E Brown Peak, Unimak Is, Ak · Ak18.20 m140 kmUnited States
S Sennett Point, Unimak Is, Ak · Ak17.60 m174 kmUnited States
Promontory Cove, Unimak Is, Ak · Ak17.10 m152 kmUnited States
Northeast Coast Hawaii, Hi · Hi16.80 m3,744 kmUnited States

More tsunamis in United States

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.