1957 Mongolia earthquake

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Coordinates: 45°11′20″N 99°22′05″E / 45.189°N 99.368°E / 45.189; 99.368
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1957 Mongolia earthquake
1957 Mongolia earthquake is located in Mongolia
Ulaanbaatar
Ulaanbaatar
1957 Mongolia earthquake
UTC time1957-12-04 03:37:53
ISC event887636
USGS-ANSSComCat
Local dateDecember 4, 1957 (1957-12-04)
Local time11:37:53
MagnitudeMw 7.8–8.1, Ms 8.0–8.5[i]
Depth20.0 km[8]
Epicenter45°11′20″N 99°22′05″E / 45.189°N 99.368°E / 45.189; 99.368
Areas affectedMongolian People's Republic
Max. intensityMMI XII (Extreme)[7]
AftershocksYes, Ms  6.5[7] & M 6.8[9]
Casualties30[10]

An earthquake occurred in southern Mongolia on December 4, 1957, measuring

Surface faulting
was observed in the aftermath with peak vertical and horizontal scarp reaching 9 m (30 ft). Because of the extremely sparse population in the area, this event, despite its magnitude, was not catastrophic. However, 30 people died and the towns of Dzun Bogd, Bayan-leg and Baruin Bogd were completely destroyed.

Tectonic setting

As the

Paleoseismological investigation revealed that the average recurrence interval of earthquakes like the 1957 event on the fault had decreased from 50 kyr[ii] to 3-14 kyr in the late Pleistocene.[14] The Bogd fault is a large left-lateral strike-slip fault.[12] It is split into five distinct segments.[12] Slip rates vary between segments, but it is between 0.5–1 mm (0.020–0.039 in)/yr overall.[12] Recurrence intervals of 1957 type events on the Bogd fault have been calculated at around 1,000 years.[15] Other large (Mw8.0+) earthquakes had struck Mongolia in the previous half century, including the 1905 Tsetserleg, 1905 Bolnai, and 1931 Fuyun earthquakes. Some studies indicate that these earthquakes triggered each other, with the earlier ones triggering the later events.[16][17]

Earthquake

The earthquake struck southern Mongolia at 11:37:53 local time on December 4, 1957. Rupture was complex, with multiple scenarios proposed. The original hypothesis was that the earthquake occurred along the strike-slip Bogd fault and ruptured for 560 km (350 mi),

reverse faulting in a roughly east-west direction.[14][18][19][13] Offsets from surface rupture reached up to 8.85 m (29.0 ft) of strike-slip rupture,[18] with 9 m (30 ft) vertical offsets,[15] and an average slip of 3–4 m (9.8–13.1 ft).[13][14] According to a study on the earthquake's surface rupture, the authors consider the rupture the "world's best preserved surface rupture of a great earthquake".[20] The average slip decreased from west to east.[12] Ruptured fault splays were observed up to 30 km (19 mi) away from the main fault trace.[13] Large aftershocks struck the epicentral region after the mainshock. Shortly after the mainshock, a Ms  6.5 event struck.[7] On April 7, 1958, another large earthquake measuring M 6.8 struck, located in the epicentral region of the mainshock.[9]

Impact

Despite attaining the maximum value on the Modified Mercalli intensity scale of XII (Extreme), the earthquake did not cause significant disruption to population centers owing to its remote and unpopulated location.[21] Dzun Bogd, Bayan-leg and Baruin Bogd, however, were destroyed.[9] Due to good weather, shepherds of these herding communities were outside, which limited the death toll to 30.[9][21] Major geological effects were also observed. Surface offsets reaching 9 m (30 ft) of both strike-slip and vertical motion were observed after the event.[18][15] Subsidence was also observed. At the Bakhar Mountains [ceb], a 15 km (9.3 mi) long and 800 m (2,600 ft) wide portion of the earth subsided due to the earthquake.[9] In the Bitüüt valley, a large landslide was triggered.[20]

See also

Notes

  1. ^ M 7 3/4 - 8,[1] Mw  7.78-7.95,[2][3] Mw  8.1,[4] Ms  8.0,[5] Ms  8.3,[6] Ms  8.5[7]
  2. ^ kyr = thousand years

References

  1. ^ a b Ben-Menahem & Toksöz 1962, p. 1943.
  2. ^ Rizza et al. 2011, p. 918.
  3. ^ Molnar & Qidong 1984, p. 6210.
  4. ^ "M 8.1 - 153 km SW of Bayanhongor, Mongolia". United States Geological Survey. United States Geological Survey. Retrieved January 10, 2023.
  5. ^ Okal 1976.
  6. ^ Kanamori 1977.
  7. ^ a b c d Aptikaev & Erteleva 2019.
  8. ^ Vergnolle, Pollitz & Calais 2003.
  9. ^ a b c d e Rothé 1969.
  10. ^ Bath 1973.
  11. ^ Rizza et al. 2011, p. 898.
  12. ^ a b c d e f Rizza et al. 2011.
  13. ^ a b c d Molnar & Qidong 1984.
  14. ^ a b c d e Ritz et al. 2003.
  15. ^ a b c d Baljinnyam et al. 1993.
  16. ^ Chéry, Carretier & Ritz 2001.
  17. ^ Pollitz, Vergnolle & Calais 2003.
  18. ^ a b c Chen & Molnar 1977.
  19. ^ Ben-Menahem 1977.
  20. ^ a b Kurushin et al. 1998.
  21. ^ a b "Summary of the earthquake". United States Geological Survey. United States Geological Survey. Archived from the original on June 26, 2015. Retrieved June 25, 2015.

Sources

External links
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