1995 Neftegorsk earthquake

The 1995 Neftegorsk earthquake occurred on 28 May at 1:04 local time[5] on northern Sakhalin Island in the Russian Far East.[6] It was the most destructive earthquake known within the current territory of Russia,[7] with a magnitude of Ms7.1 and maximum Mercalli intensity of IX (Violent)[8] that devastated the oil town of Neftegorsk, where 2,040 of its 3,977 citizens were killed, and another 750 injured.[9]

1995 Neftegorsk earthquake
UTC time1995-05-27 13:03:53
ISC event106336
USGS-ANSSComCat
Local date27 May 1995 (1995-05-27)
Local time1:04 a.m. local time
MagnitudeMs(HRV) 7.1 [1]
Depth11.0 km (7 mi) [2]
Epicenter52.63°N 142.83°E / 52.63; 142.83
TypeStrike-slip [3]
Areas affectedSakhalin, Russian Far East
Total damage$64.1–300 million [3]
Max. intensityIX (Violent)[4]
Casualties1,989 dead [3]
750 injured [3]

90% of the victims were killed by the collapse of 17 five-story residential buildings.[10] While Western media generally attributed the collapses to allegedly poor construction and shoddy materials of Soviet-era construction,[11] a geotechnical study faulted a failure to accommodate the possibility of soil liquefaction in an area that was considered "practically aseismic".[12]

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.[3]

1995 Neftegorsk earthquake monument in Yuzhno-Sakhalinsk

This quake was not only catastrophic, it was totally unexpected: earthquakes with magnitudes greater than 6 were not known to occur in the area of northern Sakhalin Island.[13] It is also of great scientific interest (some 20 papers have been published[14]) because it occurred near a poorly known tectonic plate boundary where the Okhotsk Plate (connected with North American Plate) is crashing into the Amurian Plate (part of the Eurasian Plate),[15] and indicates that the plate boundary is associated with a north-south striking seismic belt that runs the length of Sakhalin. More precisely, this earthquake occurred on the Upper Piltoun fault (also known as the Gyrgylan'i—Ossoy fault[16]), which branches off the main Sakhalin-Hokkaido fault that runs along the east side of the island.[17]

35 km (22 mi) of surface rupturing was observed (46 km including a branching fault), with an estimated average lateral displacement of about 4 meters, but up to 8 m (9 yd) in some places.[18] (This compares to 14 km of slip estimated to have accumulated on the Sakhalin-Hokkaido fault in the last 4 million years.[19]) The unusual strength of this quake and length of rupturing, and the low level of seismic activity beforehand, has been attributed to the accumulation of strain over a long period of time on a locked fault segment.[20]

See also

Notes
  1. ISC-EB Event 106336 [IRIS] ANSS reports this as Mwb7.1.
  2. ISC-EHB Event 106336 [IRIS].
  3. USGS (September 4, 2009), PAGER-CAT Earthquake Catalog, Version 2008_06.1, United States Geological Survey
  4. ISC-EHB Event 106336 [IRIS].
  5. Klyachko 2001, p. 1.
  6. ANSS: Sakhalin 1995.
  7. Arefiev et al. 2000, p. 595.
  8. ISC-EHB Event 106336 [IRIS]. The ANSS: Sakhalin 1995 reviewed value on the Mwb scale is also 7.1. Some sources have reported the magnitude as Ms 7.6.
  9. Earth Chronicles (2016) attributes the fatality numbers to the Russian Ministry of Emergencies. The ISC, without citing a source, says "[a]s many as 1,989 people killed" (ISC-EHB Event 106336 [IRIS]). Other sources attribute the "more than 2000" number to Japanese language sources.
  10. Klyachko 2001, p. 1. These buildings housed all but about 650 of the town's residents. Los Angeles Times 1995
  11. Los Angeles Times 1995.
  12. Klyachko 2001, p. 2.
  13. Arefiev et al. 2000, pp. 595, 605.
  14. ISC-EB Event 106336 [IRIS].
  15. Arefiev et al. 2000, p. 595; Katsumata et al. 2004, pp. 117, 129.
  16. Katsumata et al. 2004, p. 117
  17. Arefiev et al. 2000, p. 596.
  18. Arefiev et al. 2000, p. 599.
  19. Arefiev et al. 2000, p. 596.
  20. Arefiev et al. 2000, p. 606.

Sources
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