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1995 Neftegorsk earthquake

The 1995 Neftegorsk earthquake occurred on 28 May at 1:04 local time in northern Sakhalin Island in the Russian Far East. It was the most destructive earthquake known within the modern borders of Russia, with a magnitude of Mw7.1 and maximum Mercalli intensity of IX (Violent) that devastated the town of Neftegorsk. Many buildings collapsed, and 1,989 of its 3,977 citizens were killed, with another 750 injured. Infrastructure was catastrophically damaged, leading to Neftegorsk becoming a ghost town. Surface effects from the earthquake were widespread, with many geological features changing or developing. Due to its location along an uncertain plate boundary, the earthquake received considerable attention from scientists, and dozens of research papers have been written about it.

1995 Neftegorsk earthquake
Destruction in Neftegorsk following the earthquake
1995 Neftegorsk earthquake is located in Far Eastern Federal District
1995 Neftegorsk earthquake
UTC time1995-05-27 13:03:52
ISC event106336
USGS-ANSSComCat
Local date28 May 1995 (1995-05-28)
Local time1:04 a.m.
MagnitudeMwb (USGS) 7.1[1][a]
Depth11.0 km (7 mi)[1]
Epicenter52°38′N 142°50′E / 52.63°N 142.83°E / 52.63; 142.83
FaultUpper Piltun fault
TypeStrike-slip[6]
Areas affectedSakhalin, Russian Far East
Total damage$64.1–300 million[6]
Max. intensityMMI IX (Violent)[7]
Casualties1,989 dead[6]
750 injured[6]

Tectonic setting

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Sakhalin lies along the destructive plate boundary zone between the Amur microplate (part of the Eurasian plate system) and the Okhotsk microplate (part of the North American plate) system. The Sakhalin-Hokkaido fault is the main plate boundary in Sakhalin with a slip rate of 4 mm (0.16 in)/yr, and runs along the island.[8][9][10] In North Sakhalin, however, faulting is predominantly strike-slip and not reverse. In the area near the earthquake, three faults take up the brunt of the slip: the Gyrgylanye-Dagy, Piltun-Goromai, and Upper Piltun (also known as the Verkhnii Pil’tun or Gyrgylan’i–Ossoy) faults. The Piltun-Goromai fault runs along the eastern coast of Sakhalin for 40–90 km (25–56 mi) in a roughly north-south alignment with a slip rate of 3–5 mm (0.12–0.20 in)/yr.[11] Along the Piltun-Goromai fault, strong earthquakes recur every every 2,300 - 5,000 years.[12] The Upper Piltun fault—which ruptured in this earthquake—branches west of the Piltun-Goromai fault and runs south-south-west until it reaches the Gyrgylanye-Dagy fault.[13] 3 large events in the past 1,800 years have been identified along the Upper Piltun fault.[12] A magnitude 7.8 earthquake occurred on the fault 2,600 years ago, and another large event occurred 4,000 years ago.[12][14] Recurrence interval of large earthquakes on the Upper Piltun fault is estimated to be 400 years.[11] The fault was locked and accummulated stress before the earthquake between 1941-1970.[15] The Gyrgylanye-Dagy fault is the westernmost of the three, running parallel to the Piltun-Goromai fault. The slip rate is estimated to be at least 1 mm (0.039 in)/yr.[16] Prior to this earthquake, North Sakhalin had been relatively aseismic, with the largest earthquake in the area being the Mw 5.8 Nogliki earthquake of 1964.[17]

Earthquake

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The earthquake struck on May 28 at 1:04 local time[18] in northern Sakhalin in the Russian Far East near the town of Neftegorsk. This Mw 7.1 earthquake had a maximum Mercalli intensity of IX (Violent), with ESI intensity reaching XI.[7][19] The earthquake was also recorded as Ms 7.2-7.6 and Muk 7.8.[3][4][5] The right-lateral strike-slip rupture along the Upper Piltun fault was 35–46 km (22–29 mi) long, with an average slip of 3.6–3.9 m (12–13 ft). Horizontal slip peaked at 8.1 m (27 ft), with the minor vertical component peaking at 1.5–1.7 m (4 ft 11 in – 5 ft 7 in).[20][21] The stress drop as a result of this quake was 4-11 MPa.[22] The earthquake was felt widely across the island, and nearby portions of mainland Asia experienced shaking as well.[3] Sabo and Tungor experienced MSK VII (Very strong), Okha and Nogliki felt MSK VI (Strong), and Lazarev on the mainland felt MSK IV (Largely observed) shaking. There were over 1,000 small aftershocks recorded in the first month and a half, with none exceeding Ms 5.[23][24] The aftershocks spanned a length of 60–80 km (37–50 mi).[3][22]

Impact

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Aerial view of Neftegorsk after disaster

Due to the previous lack of strong earthquakes in the area, Neftegorsk was hit hard as it was unprepared. During the earthquake, 17 five-story residential buildings collapsed, leading to the deaths of 1,989 and 750 more injured. These buildings housed a majority of the town, and 90% of the fatalities were from the collapses. These buildings were only designed to withstand MSK VI (Strong) rather than the IX (Destructive) - X (Devastating) experienced in reality.[18][21][25] The 650 residents who lived in the shorter brick buildings—which didn't collapse—survived the earthquake.[26] In nearby Okha, balconies fell off of buildings and furniture broke.[27] This earthquake was the most destructive earthquake ever recorded within modern day Russian borders.[28]

The shock instantly cut off power, water, and telephone lines.[29] The quake severely damaged infrastructure, with "destruction of buildings, bridges, railways and roads, breakage of oil and gas pipelines, electric and communication lines".[3] The administration building, a building to generate heat, and some shops were also destroyed.[30] The destroyed railway had deformation up to 300 m (980 ft) long, with locations close to the rupture even experiencing wave-like bends. Two oil pipelines were badly damaged in the area, and they resultantly began leaking oil which seeped into small lakes. Telegraph poles, railways beds, and even a locomotive at the railway station all shifted to the east-southeast.[31] The Belgian Centre for Research on the Epidemiology of Disasters' EM-DAT database places the total damage at $64.1 million, while the United States' National Geophysical Data Center assesses the damage at $300 million.[6]

Geological effects

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The earthquake caused significant surface changes, including landslides, new islands, surface fractures, liquefaction, and mud volcanoes. Landslides damaged roads, and were observed on almost every coastal slope near the rupture area. The largest landslide was 50 km3 (12 cu mi) and blocked the Cadylanye River for a bit. Mud volcanoes cropped up both near the fault and dozens of kilometers away, with the best example occurring 25 km (16 mi) from the source. The mud volcanoes were varied, with almost every single type of volcano structure represented on the mud volcanoes formed after the earthquake. Surface ruptures were widespread.[32] In the Piltun Bay, several new small, sandy islands formed.[33] Liquefaction was observed outside the epicentral region along the seashore.[19]

Response

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Immediately after the earthquake struck, Russian rescue teams from the surrounding areas prepared to deliver aid. 18 planes and helicopters were prepared; however, some were unable to deliver their aid due to heavy fog preventing landings. Since the temperatures in Sakhalin were bitterly cold, the cargo included blankets along with food. The Russian government released 30 billion rubles to use on rescue and aid.[26] Authorities were able to secure basic necessities for survivors, with food, water, and shelter being taken care of.[34] The largest transport planes faced challenges in delivering their cargo to Neftegorsk as they could not land at the nearby airport as the planes were too big.[29] Field hospitals were set up and hundreds of injured victims were medevaced to larger nearby cities like Khabarovsk.[35]

Aftermath

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After the rescue operations had been carried out and things had settled down, Moscow decided not to rebuild Neftegorsk. Residents longed to get away from the horror they experienced during the earthquake, so few had interest in remaining. When offered the chance to move elsewhere on Sakhalin island by government officials, the former residents only wanted compensation rather than to remain on the island.[36] After the earthquake, the town completely emptied out and became a ghost town. Due to the unprecedented and unpredicted seismicity in the area, the building code and seismic risk maps were soon updated to reflect the earthquake and its impacts.[13]

Scientific interest

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This event occurred on the poorly defined plate boundary between the Amur microplate and the Okhotsk microplate in an area where no large earthquakes were previously known.[37] Due to this, many scientific studies were conducted to help understand the earthquake and the tectonic background of the area it struck in. A total of 26 research papers have been published on the earthquake itself.[7] Despite many seismic sensors being removed from the island just before the earthquake due to a lack of funding, the earthquake still provided valuable insight into understanding and resolving the poorly understood plate boundary.[3][38]

See also

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Notes

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  1. ^ ISC reports it as Mw(ISC) 7.1[2], a research paper reports it as Ms 7.2.[3], other research papers put it at Ms 7.6[4], while yet another paper reports it as a magnitude 7.8, scale unknown[5]

References

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  1. ^ a b "M 7.1 - 85 km S of Tungor, Russia". United States Geological Survey. Retrieved 10 December 2024.
  2. ^ International Seismological Centre. Event Bibliography. Thatcham, United Kingdom. [Event 106336].
  3. ^ a b c d e f Ivaschenko et al. 1997, p. 288.
  4. ^ a b Arafiev et al. 2006, p. 595.
  5. ^ a b Nicholson, VanLaningham & MacDonald 2013, p. 590.
  6. ^ a b c d e "PAGER-CAT Earthquake Catalog". Version 2008_06.1. United States Geological Survey. September 4, 2009.
  7. ^ a b c International Seismological Centre. ISC-EHB Bulletin. Thatcham, United Kingdom. [Event 106336].
  8. ^ Arefiev et al. 2000.
  9. ^ Arafiev et al. 2006.
  10. ^ Aref'ev & Dorbath 2001.
  11. ^ a b Kozhurin 2004, p. 277.
  12. ^ a b c Chapter 8 Geological Hazards in the Project Area (PDF) (Report). 2005-11-23. Retrieved 2024-12-23.
  13. ^ a b Ivaschenko et al. 1997, p. 300.
  14. ^ Zhigulev & Patrikeev 2007, p. 18.
  15. ^ Vasilenko, Prytkov & Saprygin 2011, p. 234.
  16. ^ Nicholson, VanLaningham & MacDonald 2013, p. 598.
  17. ^ Arefiev et al. 2000, p. 597.
  18. ^ a b Klyachko 2001, p. 1.
  19. ^ a b Tatevossian et al. 2009, p. 85.
  20. ^ Arefiev et al. 2000, p. 599.
  21. ^ a b Ivaschenko et al. 1997, p. 294.
  22. ^ a b Katsumata et al. 2004, p. 120.
  23. ^ Arefiev et al. 2000, p. 606.
  24. ^ Arafiev et al. 2006, p. 858.
  25. ^ Melentyev 1999, p. 229-230.
  26. ^ a b Efron, Sonni (May 29, 1995). "7.5 Quake Kills 300 on Russia's Sakhalin Island". LA Times. LA Times. Retrieved 7 December 2024.
  27. ^ "Quake on Russian Island in Pacific Kills at Least 300". The New York Times. Associated Press. 29 May 1995. Retrieved 29 February 2024.
  28. ^ Arefiev et al. 2000, p. 595.
  29. ^ a b "The Sakhalin Earthquake of May 27, 1995" (PDF). EERI Special Report. 1995. Retrieved 29 February 2024.
  30. ^ Johnson 1998, p. 59.
  31. ^ Ivaschenko et al. 1997, p. 295, 298.
  32. ^ Ivaschenko et al. 1997, p. 288, 297-298.
  33. ^ Kharakhinov, Litvinov & Beketsky 1997.
  34. ^ "Russian Federation - Sakhalin Island Earthquake Situation Report No.10". ReliefWeb. 3 June 1995. Retrieved 24 December 2024.
  35. ^ Johnson 1998.
  36. ^ Boudreaux, Richard. "Next Step : Erasing Another Communist Error : Neftegorsk was a village that never should have been. Now a tragic quake and Khrushchev's heirs are 'correcting' his folly". LA Times. LA Times. Retrieved 24 December 2024.
  37. ^ Katsumata et al. 2004, p. 117.
  38. ^ Katsumata et al. 2004, p. 129.

Sources

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