April 1, 1946 Tsunami: Unimak Island, AK, United States

Ref #414:

On April 1, 1946, at 01:29 local time [April 1, 12:29 UTC] a rather strong magnitude 7.4 earthquake occurred with source to the south of Unimak Island, causing one of the most destructive tsunamis in the Pacific Ocean. The rise of water was 30 m in the Aleutian Islands (Unimak Island), 17 m on the Hawaiian Islands (Island of Hawaii), 9-10 m (?) in the Marquesas Islands and the Juan Fernandez Islands, 3 m in the USA (Santa Cruz and Half Moon Bay), no more than 1 m in Japan (Ayukawa).

Ref #239:

[…] the earthquake rupture occupied a block about 100 miles long by about 50 miles wide between southeast of Scotch Cap and southeast of Sanak Islands. There is still a question how this relatively small earthquake produced such a large Pacific-wide wave. […] At about 1:30 A.M., April 1, local time, the log of the U.S. Coast Guard Direction Finding Station on Unimak Island noted, "Severe earthquake felt. Building rocked severely. Objects shaken from locker shelves. Duration approximately 30-40 seconds ..." […] The Coast Guard ship Cedar reported that the tidal wave had destroyed two houses and two sheds at Ikatan and destroyed the Pankof light at the southeast end of Unimak Island. […] [Tsunami] caused about $250,000 in damage in Alaska, mostly to the nearly new Scotch Cap Lighthouse (which cost $150,000 to build in 1940). It caused 5 fatalities at that facility. […] caused $10,000 and one fatality in California, and $26 million in damage and 159 fatalities in Hawaii [96 at Hilo, Ref #236]. This led to the development of tsunami travel time charts for the Pacific and the Pacific Tsunami Warning Service.

Ref #237:

Warnings were issued to many communities through the Coast Guard although a formal system for doing so was not yet in place. Some communities took precautions in evacuating lowlying areas. The warnings triggered another phenomena which has plagued mitigation efforts in all subsequent events. They triggered a reverse response in attracting crowds to the beach. This event happened on April 1, April Fools Day, and some mistook the warning and reports of a tsunami as a hoax.

Ref #150:

Hawaiian Islands great damage, 173 deaths, Hilo: 448 structures destroyed. 78 deaths.

Ref #7099:

... through interviews I conducted with survivors at Laupahoehoe, I discovered that a little girl killed there was counted twice because she was adopted and listed under two different names. So, the 1946 tsunami actually killed 158 people in Hawaii and not 159...

Ref #4289:

The source of the 1946 Aleutian tsunami may have involved a significant underwater landslides, a suggestion supported by recent identification of geologically fresh slides along the shelf edge to the west.

Ref #11012:

The emerging picture is that the event involved both a very slow earthquake, responsible for the far-field tsunami, and a major landslide explaining the near-field run-up, but with a negligible contribution in the far field.

Note: Deaths: 5 in Alaska, 158 in Hawaii, 3 in Marquesas, 1 in California and 1 in Peru