Английская Википедия:1957 Andreanof Islands earthquake

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Шаблон:Short description Шаблон:Infobox earthquake

The 1957 Andreanof Islands earthquake occurred at 04:22 local time on March 9 with a moment magnitude estimated between 8.6 and 9.1 and a maximum Modified Mercalli intensity of VIII (Severe). It occurred south of the Andreanof Islands group, which is part of the Aleutian Islands arc. The event occurred along the Aleutian Trench, the convergent plate boundary that separates the Pacific Plate and the North American plates near Alaska. A basin-wide tsunami followed, with effects felt in Alaska and Hawaii, and strong waves recorded across the Pacific rim. Total losses were around $5 million.

Tectonic setting

Файл:Alaska earthquakes.jpg
Map showing the tectonics and seismicity of Alaska

The Aleutians Islands lie between Kamchatka and mainland Alaska. They were formed as the result of the Шаблон:Convert long convergent boundary that accommodates the subduction of the oceanic Pacific Plate underneath the continental North American Plate.[1] This oceanic trench runs from the Kuril-Kamchatka Trench in the west to the Yakutat Collision Zone in the east. Most of the trench ruptured in a sequence of earthquakes from east to west.Шаблон:Sfn Earthquakes in 1938, 1946, 1948, and 1965 generally progressed westward with smaller earthquakes filling in any gaps.Шаблон:Sfn At each terminus of the subduction zone, convergence ends in favor of right-lateral transform faults.Шаблон:Sfn In the west, convergence becomes increasingly oblique until the Commander Islands where faulting is nearly completely strike-slip—a 2017 earthquake was associated with this tectonic setting.Шаблон:Sfn The plate boundary ends at the Kuril-Kamchatka Trench.Шаблон:Sfn In the east, the Pacific Plate continues to subduct underneath the North American plate until the Yakutat microplate.Шаблон:Sfn There, a transition from subduction to strike-slip faulting exists.Шаблон:Sfn When this transition ends, faulting is completely right-lateral transform and is largely accommodated along the Queen Charlotte Fault.Шаблон:Sfn

Earthquake

The seismic intensity peaked at VIII (Severe) on the Modified Mercalli intensity scale at Adak and Umnak.Шаблон:Sfn As the shock occurred before the World Wide Standardised Seismological Network was in operation, few instruments recorded 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 Шаблон:Convert aftershock zone was the largest that had ever been observed.Шаблон:SfnШаблон:Sfn The aftershock zone may slightly overlap other ruptures, however there is minimal overlap between the aftershocks of the 1946 Aleutian Islands earthquake to the east and the 1965 Rat Islands earthquake to the west.Шаблон:Sfn StudiesШаблон:Specify of the event differ on rupture characteristics. Some suggest a rupture zone greater than Шаблон:Convert, stretching from Amchitka Pass in the east to Unimak Pass in the west.Шаблон:Sfn Other studiesШаблон:Specify have the rupture area at a significantly longer Шаблон:Convert.Шаблон:Sfn Yet other studiesШаблон:Specify conclude that the entirety of the aftershock area ruptured in the earthquake, for a total rupture length of Шаблон:Convert.Шаблон:Sfn The western portion of the rupture stopped at Bowers Ridge.Шаблон:Sfn Studies also disagree on whether the easternmost area near Unalaska ruptured. Some of the early scientific papersШаблон:Specify conclude that this area remained unruptured during the event and remains a seismic gap.Шаблон:Sfn Others, especially ones written decades after the fact, conclude that slip did occur here,Шаблон:Sfn but signals from it were blocked by the coda of the main slip.Шаблон:Sfn However, the amount of slip is not agreed upon. Some studies support a low amount of slip,Шаблон:Sfn while others conclude that there was large amounts of slip in this area,Шаблон:Sfn up to Шаблон:Convert.Шаблон:Sfn A maximum slip of Шаблон:Convert was estimated in the eastern portion of the rupture.Шаблон:Sfn If the eastern portion of the megathrust did rupture, then a magnitude of Шаблон:M is more reflective of the event.Шаблон:Sfn The tsunami created by the earthquake suggests a (Шаблон:M) event.Шаблон:Sfn

Tsunami

Teletsunami observationsШаблон:Sfn[2]
Location Recorded height (m)
Hāʻena, Kauai County, Hawaii, Hawaii 16.1
Wainiha, Hawaii, Hawaii 11.6
Pololu Valley, Hawaii 9.8
Oahu, Hawaii 7.0
Fagasā, American Samoa 1.5
Crescent City, California 0.7
San Diego, California 0.2

Tsunami waves were reported in far way places such as in Chile.Шаблон:Sfn The tsunami's strength led to suspision that a landslide may have contributed to its severity, but there is no evidence of a landslide.Шаблон:Sfn A submarine landslide is considered inconsistent with the wave patterns recorded, and the high wave heights could be explained by large amounts of near trench slip.Шаблон:Sfn

Alaska

Wave heights were the highest in Alaska. On Unimak Island, waves reached as high as Шаблон:Convert.[2] Also on Unimak, near the Scotch Cap Lighthouse that was destroyed in the 1946 earthquake, run up heights of Шаблон:Convert were observed.Шаблон:Sfn Trappers Cove recorded wave heights of Шаблон:Convert.Шаблон:Sfn At Sand Bay, the tsunami reached Шаблон:Convert.Шаблон:Sfn Dutch Harbor in Unalaska recorded waves of Шаблон:Convert, Massacre Bay in Attu recorded waves up to Шаблон:Convert high and Sitka had waves reaching Шаблон:Convert.Шаблон:Sfn At Yakutat run-ups measured Шаблон:Convert, while Women's Bay, Kodiak, Seward, and Juneau had recorded tsunami heights of Шаблон:Convert.Шаблон:Sfn

Hawaii

On the island of Kauai, the wave height reached Шаблон:Convert at Haena.Шаблон:Sfn In northern Oahu, wave heights reached Шаблон:Convert.Шаблон:Sfn Various areas around Big Island recorded tsunami waves with heights ranging Шаблон:Convert,Шаблон:Sfn including a reading of Шаблон:Convert at Hilo.[3] In Kahului, Maui, tide gauges recorded waves up to Шаблон:Convert.Шаблон:Sfn Coconut Island was submerged by Шаблон:Convert.Шаблон:Sfn

California

Crescent City recorded a tsunami wave of Шаблон:Convert.Шаблон:Sfn Los Angeles recorded run-ups of Шаблон:Convert, Santa Monica experienced a Шаблон:Convert-high tsunami, while Anaheim Bay had Шаблон:Convert waves.Шаблон:Sfn San Francisco's tide gauge recorded run-ups of Шаблон:Convert.Шаблон:Sfn In San Diego, a Шаблон:Convert wave caused minor damage, however the tide gauge only recorded a wave Шаблон:Convert high.Шаблон:Sfn Other tide gauges across the state recorded run-up heights of Шаблон:Convert.Шаблон:Sfn

Elsewhere

At Fagasā, American Samoa, tsunami run-up heights reached Шаблон:Convert.Шаблон:Sfn Pago Pago recorded wave heights of Шаблон:Convert, however the amplitude of the wave was Шаблон:Convert.Шаблон:Sfn Midway recorded tsunami waves up to Шаблон:Convert high.Шаблон:Sfn Wake Island recorded amplitudes of Шаблон:Convert, Kwajalein and Enewetak recorded heights of Шаблон:Convert.Шаблон:Sfn Johnston Atoll experienced waves of Шаблон:Convert, while waves less than Шаблон:Convert were recorded at Guam and Chuuk Lagoon.Шаблон:Sfn In Mexico, the tidal gauge in Ensenada, Baja California recorded the strongest waves at Шаблон:Convert.Шаблон:Sfn Many countries in Central America also recorded tsunami run-ups including Шаблон:Convert at Puntarenas, Costa Rica, Шаблон:Convert at Puerto San José, Guatemala, and Шаблон:Convert waves at La Unión, El Salvador.Шаблон:Sfn Peru and Chile were favorably oriented for large waves from the tsunami, and as a result strong waves were recorded. In Peru, the strongest wave heights of Шаблон:Convert were recorded at Matarani, with other coastal areas recording wave heights of Шаблон:Convert.Шаблон:Sfn Valparaiso, Chile recorded wave heights of Шаблон:Convert, which were the highest across the country.Шаблон:Sfn Across the rest of the country, wave heights of Шаблон:Convert, Шаблон:Convert, Шаблон:Convert, and Шаблон:Convert were recorded at Arica, Antofagasta, Caldera, and Talcahuano, respectively.Шаблон:Sfn

Damage

Prompt warnings from the Seismic Sea Wave Warning System were credited with preventing major damage or loss of life.Шаблон:Sfn The earthquake caused severe damage to roads and buildings on Adak including a crack Шаблон:Convert in size,Шаблон:Sfn however there were no deaths.Шаблон:Sfn Two bridges and some oil and fuel-related structures at a dock were also destroyed there.Шаблон:Sfn On Umnak, a concrete mixer and some docks were lost.Шаблон:Sfn At Chernofski,[4] Trappers Cove, and Vsevidof, strong waves drowned sheep.Шаблон:Sfn Oil pipelines were damaged at Sand Bay.Шаблон:Sfn Many boats were damaged from strong waves.Шаблон:Sfn

The tsunami caused twice the damage the tsunami of the 1946 earthquake did.Шаблон:Sfn 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. About 50 homes were flooded on the north shore of Oahu and significant effects were seen in Waialua Bay. Buildings and bridges were also flooded in Haleiwa.Шаблон:Sfn In Hilo, the tsunami damaged buildings.[3] The total damage cost was over $5 million ($46 million in 2017).[2]

See also

Notes

Шаблон:Notelist

References

Шаблон:Reflist

Sources Шаблон:Refbegin Шаблон:Cite journal

Шаблон:Refend

External links

Шаблон:Earthquakes in 1957 Шаблон:Earthquakes in Alaska Шаблон:Earthquakes in the United States Шаблон:Alaska history footer

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  1. ↑ Ошибка цитирования Неверный тег <ref>; для сносок AleutianTrench не указан текст
  2. ↑ 2,0 2,1 2,2 Ошибка цитирования Неверный тег <ref>; для сносок Tsunami1957 не указан текст
  3. ↑ 3,0 3,1 Ошибка цитирования Неверный тег <ref>; для сносок UWTsunami не указан текст
  4. ↑ Ошибка цитирования Неверный тег <ref>; для сносок UNESCO1957 не указан текст
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