1957 Aleutian Tsunami

  During the early morning hours of March 9, 1957, a magnitude 8.3 earthquake struck along a section of the Aleutian Trench located south of the Andreanof Islands (the section of the Aleutian Islands shown above). The vertical seafloor displacement that accompanied this quake generated a major Pacific-wide tectonic tsunami, similar to the 1946 Aleutian event, but fortunately smaller. The 1957 event is not as well documented as that of 1946, which is probably do to the fact that it struck hardest at the sparsely populated Aleutian Islands, while more populated areas, such as Hawaii and California, received smaller waves.  

Effects at the Aleutian Islands

  Though the only reported casualties across the Aleutian Islands were sheep, the tsunami did generate some impressive wave heights, as shown on the map above (black triangles). Eight-foot waves struck at Adak Island. The tsunami destroyed houses and boats at the harbor of Atka Island. Wave heights reached 40 feet near the Scotch Cap Lighthouse at Unimak Island, and were reportedly up to 75 feet high on the Pacific side of Umnak Island. As was the case with tsunami of 1946, the Aleutian Islands shielded the Alaskan mainland from the effects of the tsunami.  

Effects at Hawaii

 

Unlike the situation during 1946, this time the Hawaiian Islands received advanced warning of the approaching tsunami, which provided Hawaiian authorities with sufficient time to spread the warning, and evacuate low lying areas. As a result, there were no fatalities directly associated with the 1957 tsunami. The damage caused by the tsunami to the Hawaiian Islands as a whole was also less than that of 1946, due to the fact that in general, the 1957 tsunami waves were smaller than those of 1946, especially at densely populated areas such as the city of Hilo.

At Hilo, on the Island of Hawaii, tsunami runup was 10 feet above sea level. Many buildings along unprotected section of the shore at Hilo were badly damaged by the waves, but the downtown area was mostly spared due to the presence of the coastal barrier and parkway, which buffered downtown Hilo against the tsunami. This time damages at Hilo totaled only 150,000 dollars.

Other Islands in the Hawaiian chain however, were not as lucky as Hawaii. Damage to the island of Kauai, where the tsunami runup reached 32 feet above sea level, was greater than that produced by the 1946 tsunami. The tsunami destroyed boats and homes at the Island of Maui, where tsunami runup reached 23 feet above sea level at Waimea Bay.

 

Effects at the United States West Coast

  The tsunami of 1957 was noticed in several locations along the Pacific coast of the United States, but caused little damage, and no fatalities. Crescent City, California, recorded an amplitude of 1.3 feet. Port Hueneme reported a 3.5-foot maximum wave height. Shelter Island in San Diego was struck by a three-foot surge, which damaged boats and docking facilities.  

Effects at Other Pacific Locations

  The 1957 Aleutian tsunami was recorded as a ten-foot surge at the Marquesas Islands of French Polynesia, and also struck Chile as a six-foot wave.  
 

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