2017 Komandorski Islands earthquake

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2017 Komandorski Islands earthquake
Relief Map of Kamchatka Krai.png
Bullseye1.png
UTC  time2017-07-17 23:34:13
ISC  event 610785483
USGS-ANSS ComCat
Local dateJuly 18, 2017
Local time11:34:13
Duration> 80 seconds
Magnitude7.8 Mw [1]
Depth8.4 km [1]
Epicenter 54°26′35″N168°51′25″E / 54.443°N 168.857°E / 54.443; 168.857
FaultBering Fracture Zone
Type Strike-slip (Dextral)
Areas affectedRussia
Total damageNone
Max. intensity MMI VII (Very strong)
Tsunami0.3 ft
ForeshocksYes
AftershocksYes

On July 18, 2017, an earthquake struck near the Komandorski Islands, east of the Kamchatka Peninsula in the Bering Sea at 11:34 local time (23:34 UTC on July 17). Although there were no casualties from this earthquake, it was notable for a rare characteristic known as supershear, and is one of the few times a large supershear earthquake has been observed. It was preceded by a few foreshocks months earlier, and aftershocks that continued for nearly six months. [2]

Contents

Tectonic setting

The Mw  7.8 earthquake nucleated along the Bering fracture zone, parallel to the Aleutian Islands arc and Aleutian Subduction Zone. This is a transform fault between the Pacific and North American plates, and in between, the Komandorski Sliver. Formed from the highly oblique movement of the Pacific plate, the direction of convergence is nearly parallel to the trench at 7.8 mm/yr. [3] The Bearing Fracture Zone acts as a back-arc fault to accommodate the lateral motion at a rate of 5.1 mm/yr. The same fracture zone may have produced a similar sized earthquake in 1929 close to the Near Islands of Alaska. [4] Energy released from this earthquake was sufficient to accommodate strain built-up since the last earthquake on that section of fault in 1858. [3]

Earthquake

Initially registering a magnitude 7.4, the earthquake was quickly revised to a 7.7 by the US Geological Survey. [5] No loss of life or property damage was reported following the earthquake due to the remoteness of the event, although it could be felt by people. Shaking intensities V to VI was felt at Bering Island, and in Petropavlovsk-Kamchatsky, was felt as II. [6] Tsunami warning was issued but cancelled a few less than two hours later. [7] A non-destructive tsunami of 0.3 feet was observed. [8] The small tsunami was attributed to the lack of vertical displacement during the event.

The earthquake focal mechanism was almost pure strike-slip, and the entire rupture process took more than 80 seconds. [2] Displacements of 4 to 8.5 meters along the upper 15 km of the crust, with evidence of extension at 20 to 30 km depth. [3] Evidence of supershear was discovered when researchers realized that rupture velocity of this event increased from 2.1 km/s to 5.0 km/s after the rupture jumped onto another segment at a step-over. [9] The rupture speed far exceeded the shear wave velocity. Its rupture length of 400 km is also one of the longest in the world for a strike-slip fault, comparable to the 1906 San Francisco and 2001 Kokoxili earthquake. [2]

Foreshocks and aftershocks

A magnitude 6.7 earthquake occurred close to Attu Station, Alaska on 2 June, and a 6.3 thirteen hours before that. [10] [11] The 2 June 6.3 event had a foreshock of its own on 27 March. [12] [6]

Nearly all of the aftershocks from this earthquake were relatively small, mostly in the M4.0s range, which meant that the initial quake had released most of the strain that had been building-up. The largest aftershock was an M 6.2 on January 25, 2018. [13] On December 12, a 7.3 struck near the Kamchatka Peninsula with strike-slip mechanism was not part of the aftershock sequence, but was likely triggered by stress transfer from the July 17 quake. [14] [6]

See also

Related Research Articles

Megathrust earthquakes occur at convergent plate boundaries, where one tectonic plate is forced underneath another. The earthquakes are caused by slip along the thrust fault that forms the contact between the two plates. These interplate earthquakes are the planet's most powerful, with moment magnitudes (Mw) that can exceed 9.0. Since 1900, all earthquakes of magnitude 9.0 or greater have been megathrust earthquakes.

<span class="mw-page-title-main">1946 Aleutian Islands earthquake</span> Earthquake near the Aleutian Islands, Alaska

The 1946 Aleutian Islands earthquake occurred near the Aleutian Islands, Alaska on April 1, 1946. The shock measured 8.6, Mt 9.3 or 7.4. It had a maximum Mercalli intensity of VI (Strong). It resulted in 165–173 casualties and over US$26 million in damage. The seafloor along the fault was elevated, triggering a Pacific-wide tsunami with multiple destructive waves at heights ranging from 45–138 ft (14–42 m). The tsunami obliterated the Scotch Cap Lighthouse on Unimak Island, Alaska among others, and killed all five lighthouse keepers. Despite the destruction to the Aleutian Island Unimak, the tsunami had almost an imperceptible effect on the Alaskan mainland.

<span class="mw-page-title-main">Kamchatka earthquakes</span> Earthquakes in the Kamchatka Peninsula, far eastern Russia

Many major earthquakes have occurred in the region of the Kamchatka Peninsula in far eastern Russia. Events in 1737, 1923 and 1952, were megathrust earthquakes and caused tsunamis. There are many more earthquakes and tsunamis originating from the region.

<span class="mw-page-title-main">Aleutian Trench</span> An oceanic trench along the southern coastline of Alaska and the Aleutian islands

The Aleutian Trench 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 3,400 kilometres (2,100 mi) from a triple junction in the west with the Ulakhan Fault and the northern end of the Kuril–Kamchatka Trench, to a junction with the northern end of the Queen Charlotte Fault system in the east. It is classified as a "marginal trench" in the east as it runs along the margin of the continent. The subduction along the trench gives rise to the Aleutian Arc, a volcanic island arc, where it runs through the open sea west of the Alaska Peninsula. As a convergent plate boundary, the trench forms part of the boundary between two tectonic plates. Here, the Pacific plate is being subducted under the North American plate at a dip angle of nearly 45°. The rate of closure is 7.5 centimetres (3 in) per year.

The 1957 Andreanof Islands earthquake occurred at 04:22 local time on March 9 with a moment magnitude estimated at 8.6 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.

The 2006 Kamchatka earthquake occurred on April 21, 2006 at 12:25 PM local time. This shock had a moment magnitude of 7.6 and a maximum Mercalli intensity of X (Extreme). The hypocenter was located near the coast of Koryak Autonomous Okrug at an estimated depth of 22 km, as reported by the International Seismological Centre. This event caused damage in three villages and was followed by a number of large aftershocks. Two M6.6 earthquakes struck on April 29 at 16:58 UTC and again on May 22 at 11:12 UTC. These earthquakes caused no deaths; however, 40 people were reported injured.

<span class="mw-page-title-main">Queen Charlotte Fault</span> Active transform fault in Canada and Alaska

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 Charlotte Fault forms a triple junction south with the Cascadia subduction zone and the Explorer Ridge. The Queen Charlotte Fault (QCF) forms a transpressional plate boundary, and is as active as other major transform fault systems in terms of slip rates and seismogenic potential. It sustains the highest known deformation rates among continental or continent-ocean transform systems globally, accommodating greater than 50mm/yr dextral offset. The entire approximately 900 km offshore length has ruptured in seven greater than magnitude 7 events during the last century, making the cumulative historical seismic moment release higher than any other modern transform plate boundary system.

In seismology, a supershear earthquake is when the propagation of the rupture along the fault surface occurs at speeds in excess of the seismic shear wave velocity. This causes an effect analogous to a sonic boom.

<span class="mw-page-title-main">2002 Denali earthquake</span> 7.9 magnitude; November 3, 2002

The 2002 Denali earthquake occurred at 22:12:41 UTC November 3 with an epicenter 66 km ESE of Denali National Park, Alaska, United States. This 7.9 Mw earthquake was the largest recorded in the United States in 37 years. The shock was the strongest ever recorded in the interior of Alaska. Due to the remote location, there were no fatalities and only one injury.

<span class="mw-page-title-main">1952 Severo-Kurilsk earthquake</span> Sixth most powerful on record; in Russia

The 1952 Severo-Kurilsk earthquake struck off the coast of the Kamchatka Peninsula. The 9.0 Mw earthquake triggered a major tsunami that hit Severo-Kurilsk, Kuril Islands, Sakhalin Oblast, Russian SFSR, USSR, on 5 November 1952 at 04:58 local time. This led to the destruction of many settlements in Sakhalin Oblast and Kamchatka Oblast, while the main impact struck the town of Severo-Kurilsk. It was the most powerful earthquake ever recorded in Russia, and the fifth most powerful earthquake ever recorded in the world since modern seismography began in 1900.

<span class="mw-page-title-main">Aleutian Arc</span> Volcanic arc in Alaska, United States

The Aleutian Arc is a large volcanic arc of islands extending from the Southwest tip of the U.S. state of Alaska to the Kamchatka Peninsula of the Russian Federation.

The 1965 Rat Islands earthquake occurred at 05:01 UTC, on 4 February. It had a magnitude of 8.7 and triggered a tsunami of over 10 m on Shemya Island, but caused very little damage.

The 2014 Aleutian Islands earthquake occurred on 23 June at 11:53 HDT (UTC-9) with a moment magnitude of 7.9 and a maximum Mercalli intensity of VIII (Severe). The shock occurred in the Aleutian Islands – part of the US state of Alaska – 19 miles (31 km) southeast of Little Sitkin Island.

<span class="mw-page-title-main">2013 Craig, Alaska earthquake</span> Earthquake in Alaska and British Columbia

The 2013 Craig, Alaska earthquake struck on January 5, at 12:58 am (UTC–7) near the city of Craig and Hydaburg, on Prince of Wales Island. The Mw 7.5 earthquake came nearly three months after an Mw  7.8 quake struck Haida Gwaii on October 28, in 2012. The quake prompted a regional tsunami warning to British Columbia and Alaska, but it was later cancelled. Due to the remote location of the quake, there were no reports of casualties or damage.

On April 13, 1923, at 15:31 UTC, an earthquake occurred off the northern coast of the Kamchatka Peninsula in the USSR, present-day Russia. The earthquake had a surface-wave magnitude (Ms ) of 6.8–7.3 and an estimated moment magnitude (Mw ) of 7.0–8.2. This event came just two months after a slightly larger earthquake with an epicenter struck south of the April event. Both earthquakes were tsunamigenic although the latter generated wave heights far exceeding that of the one in February. After two foreshocks of "moderate force", the main event caused considerable damage. Most of the 36 casualties were the result of the tsunami inundation rather than the earthquake.

<span class="mw-page-title-main">2021 Chignik earthquake</span> 7th largest earthquake in the US

An earthquake occurred off the coast of the Alaska Peninsula on July 28, 2021, at 10:15 p.m. local time. The large megathrust earthquake had a moment magnitude of 8.2 according to the United States Geological Survey (USGS). A tsunami warning was issued by the National Oceanic and Atmospheric Administration (NOAA) but later cancelled. The mainshock was followed by a number of aftershocks, including three that were of magnitude 5.9, 6.1 and 6.9 respectively.

The 2021 South Sandwich Islands earthquakes were a pair of powerful earthquakes, followed by many strong aftershocks which struck along the South Sandwich Trench in August 2021. The quakes measured 7.5 and 8.1 on the moment magnitude scale, according to the United States Geological Survey. The mainshock is tied with another event in 1929 as the largest earthquake ever recorded in the South Atlantic region, and is tied with the 2021 Kermadec Islands earthquake as the second largest earthquake of 2021.

In the early morning hours of Friday 24 December 2004, a moment magnitude 8.1 earthquake struck a remote area of the southern Tasman Sea. Its epicentre was located roughly 360 km (224 mi) northwest of the Auckland Islands of New Zealand, and roughly 600 km (373 mi) north of Macquarie Island of Australia. Shaking was reportedly felt as far as Tasmania and the South Island. The event was a complex intraplate earthquake within the Australian plate, which generated a small tsunami.

The 1979 Saint Elias earthquake affected Alaska at 12:27 AKST on 28 February. The thrust-faulting Mw 7.5 earthquake had an epicenter in the Granite Mountains. Though the maximum recorded Modified Mercalli intensity was VII, damage was minimal and there were no casualties due to the remoteness of the faulting. Damage also extended across the border in parts of Yukon, Canada.

The 1958 Kuril Islands earthquake or Etorofu earthquake was a Mw 8.3–8.4 earthquake that struck near the Kuril island of Iturup on November 6, 1958, at 22:58 UTC, or 09:58 on the 7th local time. The earthquake occurred as the result of shallow reverse faulting along the Kuril-Kamchatka Trench, and caused Modified Mercalli Intensity (MMI) X (Extreme) shaking, as well as a tsunami 5 m (16 ft) high. Iturup sustained significant damage as a result of the shaking and tsunami, with other locations along the Kuril Islands also reporting strong damage.

References

  1. 1 2 International Seismological Centre. Event Bibliography. Thatcham, United Kingdom.[Event  610785483 ].
  2. 1 2 3 Chebrov, D. V.; Kugaenko, Yu.A.; Lander, A. V.; Abubakirova, I. R.; Gusev, A. A.; Droznina, S.Ya.; Mityushkina, S.V.; Ototyuk, D.A.; Pavlov, V.M.; Titkov, N.N. (26 April 2019). "Near Islands Aleutian Earthquake with MW = 7.8 on July 17, 2017: I. Extended Rupture along the Commander Block of the Aleutian Island Arc from Observations in Kamchatka" (PDF). Izvestiya, Physics of the Solid Earth. 55 (4): 576–599. Bibcode:2019IzPSE..55..576C. doi:10.1134/S1069351319040037. S2CID   198413138.
  3. 1 2 3 Lay, Thorne; Ye, Lingling; Bai, Yefei; Cheung, Kwok Fai; Kanamori, Hiroo; Freymueller, Jeffrey; Steblov, Grigory M.; Kogan, Mikhail G. (2017). "Rupture Along 400 km of the Bering Fracture Zone in the Komandorsky Islands Earthquake (Mw 7.8) of 17 July 2017". Geophysical Research Letters. 44 (24): 12, 161. Bibcode:2017GeoRL..4412161L. doi: 10.1002/2017GL076148 . S2CID   55917937.
  4. ↑ "M 7.8 – Near Islands, Aleutian Islands, Alaska". United States Geological Survey. Retrieved 5 Dec 2020.
  5. ↑ Donegan, Brian (17 July 2017). "Massive 7.7 Magnitude Earthquake Strikes Between Russia and Alaska". The Weather Channel. Retrieved 5 Dec 2020.
  6. 1 2 3 Rogozhin, E. A.; Lutikov, A. I.; Dontsova, G. Yu.; Zhukovets, V. N. (2019). "The MW = 7.8 Earthquake of July 17, 2017 near the Commander Islands: Tectonic Position and Geodynamic Setting". Izvestiya, Physics of the Solid Earth. 55 (4). Pleiades Publishing Ltd: 600–615. Bibcode:2019IzPSE..55..600R. doi:10.1134/s1069351319040086. ISSN   1069-3513. S2CID   198415645.
  7. ↑ Shedlock, Jerzy (17 July 2017). "No tsunami expected after large earthquake off Russia". Anchorage Daily News. Retrieved 5 Dec 2020.
  8. ↑ "Public Tsunami Message Number 2 NWS National Tsunami Warning Center Palmer AK 607 PM PDT Mon Jul 17 2017". NOAA / National Weather Service. 17 July 2017. Retrieved 5 Dec 2020.
  9. ↑ Kehoe, Kiser; L., H.; D., E. (9 April 2020). "Evidence of a Supershear Transition Across a Fault Stepover". Geophysical Research Letters. 47 (10). Bibcode:2020GeoRL..4787400K. doi:10.1029/2020GL087400. S2CID   216535778 – via AGU.
  10. ↑ "M 6.8 – 200 km NW of Attu Station, Alaska". United States Geological Survey. Retrieved 5 Dec 2020.
  11. ↑ "M 6.3 – 183 km ESE of Nikol'skoye, Russia". United States Geological Survey. Retrieved 5 Dec 2020.
  12. ↑ "M 6.2 – 63 km W of Attu Station, Alaska". United States Geological Survey. Retrieved 5 Dec 2020.
  13. ↑ "M 6.2 – 48 km NE of Nikol'skoye, Russia". United States Geological Survey.
  14. ↑ "M 7.3 – 83 km W of Nikol'skoye, Russia". United States Geological Survey.
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