The 1957 Andreanof Islands earthquake took place on March 9 with a

moment magnitude The moment magnitude scale (MMS; denoted explicitly with or Mw, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. It was defined in a 1979 pape ...

of 8.6 and a maximum Mercalli intensity of VIII (''Severe''). It occurred south of the

Andreanof Islands The Andreanof Islands ( ale, Niiĝuĝim tanangis, russian: Андреяновские острова) are a group of islands in the Aleutian Islands in southwestern Alaska. They are located at about 52° North and 172°57' to 179°09' West. Geogr ...

group, which is part of the

Aleutian Islands The Aleutian Islands (; ; ale, Unangam Tanangin,”Land of the Aleuts", possibly from Chukchi language, Chukchi ''aliat'', "island"), also called the Aleut Islands or Aleutic Islands and known before 1867 as the Catherine Archipelago, are a cha ...

arc. The event occurred along the

Aleutian Trench The Aleutian Trench (or Aleutian Trough) is an oceanic trench along a convergent plate boundary which runs along the southern coastline of Alaska and the Aleutian islands. The trench extends for from a triple junction in the west with the Ulakh ...

, the convergent plate boundary that separates the Pacific Plate and the North American Plates near

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...

. A basin wide

tsunami A tsunami ( ; from ja, 津波, lit=harbour wave, ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explo ...

followed, with effects felt in Alaska and Hawaii. Total losses were around $5 million.

Tectonic setting

The Aleutian Subduction Zone is the convergent boundary of the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

and

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacific ...

s. This

oceanic trench Oceanic trenches are prominent long, narrow topographic depressions of the ocean floor. They are typically wide and below the level of the surrounding oceanic floor, but can be thousands of kilometers in length. There are about of oceanic tren ...

runs from the Kuril Subduction Zone in the west to the Yakutat Collision Zone in the east. At each end of the subduction zone are right-lateral transform faults, including the

Queen Charlotte Fault The Queen Charlotte Fault is an active transform fault that marks the boundary of the North American plate and the Pacific plate. It is Canada's right-lateral strike-slip equivalent to the San Andreas Fault to the south in California. The Queen Ch ...

in the east, and a similar structure at the far west end of the arc near

Attu Island Attu ( ale, Atan, russian: Атту, link=no) is an island in the Near Islands (part of the Aleutian Islands chain). It is the westernmost point of the U.S. state of Alaska. The island became uninhabited in 2010, making it the largest uninhabite ...

Earthquake

Because the shock occurred before the World Wide Standardised Seismological Network was in operation, few instruments captured the event, and its mechanism is not understood well as a result. Some effort was made with the limited data to gain an understanding of the rupture area and the distribution of slip. One aspect of the event that was certain was that the aftershock zone was the largest that had ever been observed.

Damage

In Alaska, the

earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...

caused severe damage to roads and buildings on

Adak Island Adak Island ( ale, Adaax, russian: Адак) or Father Island is an island near the western extent of the Andreanof Islands group of the Aleutian Islands in Alaska. Alaska's southernmost town, Adak, Alaska, Adak, is located on the island. The isl ...

, but there were no deaths. Two bridges and some oil and fuel-related structures at the dock were also destroyed there. On

Umnak Island Umnak ( ale, Unmax, Umnax; russian: Умнак) is one of the Fox Islands of the Aleutian Islands. With of land area, it is the third largest island in the Aleutian archipelago and the 19th largest island in the United States. The island is home ...

, a concrete mixer and some docks were lost. Prompt warnings from the Seismic Sea Wave Warning System were credited with preventing greater damage or loss of life. In Hawaii, damage was much more extensive, including two indirect fatalities that occurred when a pilot and photographer were killed while attempting to document the tsunami's arrival from an airplane. On the island of

Kauai Kauai, () anglicized as Kauai ( ), is geologically the second-oldest of the main Hawaiian Islands (after Niʻihau). With an area of 562.3 square miles (1,456.4 km2), it is the fourth-largest of these islands and the 21st largest island ...

, the wave height reached . By comparison, the effects were considered about twice as strong as that of the 1946 Aleutian Islands earthquake and resulting tsunami. About 50 homes were flooded on the north shore of

Oahu Oahu () (Hawaiian language, Hawaiian: ''Oʻahu'' ()), also known as "The Gathering place#Island of Oʻahu as The Gathering Place, Gathering Place", is the third-largest of the Hawaiian Islands. It is home to roughly one million people—over t ...

and significant effects were seen in Waialua Bay. Buildings and bridges were also affected in Haleiwa. The total damage cost over $5 million ($46 million in 2017).

References

External links

USGS Earthquake Hazards Program – Andreanof Islands, Alaska, Magnitude 8.6

– George Pararas-Carayannis * {{DEFAULTSORT:Andreanof Islands Earthquake 1957 earthquakes 1957 in Alaska

1957 1957 ( MCMLVII) was a common year starting on Tuesday of the Gregorian calendar, the 1957th year of the Common Era (CE) and ''Anno Domini'' (AD) designations, the 957th year of the 2nd millennium, the 57th year of the 20th century, and the 8th y ...

Andreanof March 1957 events in the United States March 1957 events in Oceania

Tectonic setting

Earthquake

Damage

See also

References

External links