1979 Ghaenat earthquakes

The 1979 Ghaenat earthquakes were a series of large earthquakes in Qaen County, Khorasan Province, northeast Iran, near the Afghanistan border. The first mainshock, known as the Korizan earthquake with a surface wave magnitude (Ms ) of 6.6 and moment magnitude (Mw ) of 6.8, struck on November 14, while the Ms  7.1 or Mw  7.2 Koli-Boniabad earthquake struck on Nobemver 27. The two mainshocks were assigned a maximum Modified Mercalli intensity of VIII (Severe) and IX (Violent) respectively.[2] The earthquakes caused extensive damage throughout northeastern Iran, killed a total of 297 to 440 people and left at least 79 injured.[3]

1979 Ghaenat earthquakes
1979 Ghaenat earthquakes is located in Iran
Mashhad
Mashhad
Kerman
Kerman
Yazd
Yazd
1979 Ghaenat earthquakes
UTC time1979-11-14 02:21:22
 1979-11-27 17:10:32
 1979-12-07 09:24:00
ISC event 
 655622
 656234
 653814
USGS-ANSSComCat
 ComCat
 ComCat
Magnitude6.6 Ms
6.8 Mw
 7.1–7.5 Ms
7.2 Mw
Depth7.9 km[1]
Epicenter33°57′43″N 59°43′34″E / 33.962°N 59.726°E / 33.962; 59.726Coordinates: 33°57′43″N 59°43′34″E / 33.962°N 59.726°E / 33.962; 59.726
TypeStrike-slip
Areas affectedIran
Max. intensityIX (Violent)
AftershocksMany. Largest is an Ms  6.0
Casualties297–440 dead, 297 injured

The pair of earthquakes in November were preceded by another large Ms  6.7 (Mw  6.5) shock on January 16, killing 200 people in the town of Bonzonabad.[2][4]

EarthquakesEdit

The 6.6 Ms  or 6.8 Mw  earthquake of November 14 was the result of rupturing the Abiz Fault; a 20-km-long,[5] north-south striking, right-lateral strike-slip fault at a shallow depth of 9.2 km.[6] A maximum horizontal slip of 1 meter and some vertical displacements were recorded during field surveys after the earthquake.[7] The southern section of the earthquake surface rupture would move once again during the 1997 Qayen earthquake.[8] The Abiz Fault with an approximate length of 125 km, is thought to have ruptured its entire length during large earthquakes in 1936 (Ms  6.0), 1997 (Mw  7.3), as well as the 1979 event, with no prior rupture before the 20th century.[9]

A major aftershock of the November 14 earthquake registered Ms  6.0 or Mw  5.9 on December 7 is thought to have resulted in a 15-km-long surface rupture to the north. The aftershock would have extended the rupture length of the Abiz Fault to a total of 35 km, but the additional 15 km of new ruptures is now thought to have been formed during a subevent of the Mw  7.2 mainshock. It is unlikely that the 15 km surface ruptures were attributed to the Mw  5.9 mainshock, due to its moderate magnitude. The earthquake has been suggested to be on a separate north–south striking structure, away from the Abiz Fault.[9]

The November 27 Ms  7.1 mainshock occurred as a result of strike-slip faulting for a length of 60 km along the left-lateral Dasht-e-Bayaz Fault. The second mainshock had a hypocenter depth of 7.9 km.[1] During the Ms  7.1 mainshock, the northern termination of the first Ms  6.6 ruptured further northeast to join the eastern section of the second earthquake rupture.[5] The second rupture is nearly perpendicular to the prior rupture.[10] The same fault produced another deadlier Ms  7.1 earthquake in 1968 west northwest of the epicenter of the 1979 quake. The 1968 earthquake ruptured the western section for the fault for about 80 km in length.[9] At least 10 km of the 1968 rupture was involved in the 1979 event.[9]

ImpactEdit

The earthquake damaged or destroyed mainly adobe-constructed buildings of the sun-dried clay type. Strong ground motion mainly of horizontal fashion caused many walls of these structures to completely detach from its roof, resulting in a collapse. More recent construction of single-storey buildings suffered small damage and were mostly intact. In one village located along a hill, the most serious damage was observed at the summit, and appear to decrease in severity downhill, suggesting the seismic waves produced by the earthquake was amplified and reflected at higher elevations on the hill. This subjected structures at the top of the hill with more intense shaking than those on lower elevations.[11]

The second earthquake destroyed 10 villages.[2]

Survivors of the earthquakes were reocated to other areas while some damaged villages were rebuilt by the government in the same place.[12]

CasualtiesEdit

Between 280 and 420 lives were lost, with a further 279 injured in the November 14 earthquake.[13] Many villages were also badly damaged in the earthquake. The earthquake struck at 5:51 local time (IST) when many adult villagers were outside their homes harvesting saffron. Most of the dead were reportedly young children left at home while their adult family members were working in the saffron fields.[11]

The second mainshock which was Ms  7.1–7.5,[14] only resulted in 20 additional deaths and injured 24 people. The death toll from the second earthquake was smaller due to the low population density of the area when the quake struck.[15]

See alsoEdit

ReferencesEdit

  1. ^ a b "International Seismological Centre Online Event Bibliography". ISC: On-Line Bulletin. International Seismological Centre. Retrieved 4 August 2021.
  2. ^ a b c National Geophysical Data Center (1972). "Search Parameters". ngdc.noaa.gov. National Centers for Environmental Information. doi:10.7289/V5TD9V7K. Retrieved 4 August 2021.
  3. ^ Carl W. Stover; Carl A. von Hake (1984). United States earthquakes, 1979, 1984, Open-File Report 84-979 (PDF). U.S. Geological Survey. pp. 138–140.
  4. ^ "M 6.7 - 32 km NE of Q?'en, Iran". earthquake.usgs.gov. USGS. Retrieved 4 August 2021.
  5. ^ a b A. Haghipour; M. Amidi (1980). "The November 14 to December 25, 1979 Ghaenat earthquakes of northeast Iran and their tectonic implications". Bulletin of the Seismological Society of America. 70 (5): 1751–1757. Bibcode:1980BuSSA..70.1751H. doi:10.1785/BSSA0700051751.
  6. ^ "International Seismological Centre Online Event Bibliography". ISC: On-Line Bulletin. International Seismological Centre. Retrieved 4 August 2021.
  7. ^ M. Berberian, J. A. Jackson, M. Qorashi, M. M. Khatib, K. Priestley, M. Talebian, M. Ghafuri-Ashtiani (1999). "The 1997 May 10 Zirkuh (Qa'enat) earthquake (Mw 7.2): faulting along the Sistan suture zone of eastern Iran". Geophysical Journal International. 136 (3): 671–694. Bibcode:1999GeoJI.136..671B. doi:10.1046/j.1365-246x.1999.00762.x.CS1 maint: multiple names: authors list (link)
  8. ^ Yasutaka Ikeda; Toshifumi Imaizumi; Hiroshi Sato; Khaled Hessami; M. M. Khatib (1999). "Surface faults associated with the Qayen, northeast Iran, earthquake of May 10, 1997". Active Fault Research. 1999 (18). doi:10.11462/afr1985.1999.18_1.
  9. ^ a b c d R. T. Walker, E. A. Bergman, W. Szeliga, E. J. Fielding (2011). "Insights into the 1968-1997 Dasht-e-Bayaz and Zirkuh earthquake sequences, eastern Iran, from calibrated relocations, InSAR and high-resolution satellite imagery". Geophysical Journal International. 187 (3): 1577–1603. Bibcode:2011GeoJI.187.1577W. doi:10.1111/j.1365-246X.2011.05213.x.CS1 maint: multiple names: authors list (link)
  10. ^ Mansour Niazi; Hiroo Kanamori (1981). "Source parameters of 1978 Tabas and 1979 Qainat, Iran earthquakes from long-period surface waves" (PDF). Bulletin of the Seismological Society of America. 71 (4): 1201–1213. doi:10.1785/BSSA0710041201 (inactive 2021-11-09).CS1 maint: DOI inactive as of November 2021 (link)
  11. ^ a b Hojjat Adeli (1981). "Ghaenat (Iran) earthquake of November 14,1979". Bulletin of the New Zealand Society for Earthquake Engineering. University of Teheran, Tehran, Iran. 14 (1): 34–36. doi:10.5459/bnzsee.14.1.34-36.
  12. ^ Reza Alaghebandian (1998). "Damage of Reinforced Concrete Frame Structures during the Iran-Qayen (Ardakul) Earthquake of May 10, 1997". Annual Papers on Concrete Engineering. Japan Concrete Engineering Association. 20 (3).
  13. ^ "Korizan-Khaf Earthquake of 14 November 1979, Ms6.6". Institute of Engineering Seismology and Earthquake Engineering. 14 November 2015. Retrieved 4 August 2021.
  14. ^ "M 7.1 - 56 km ENE of Q?'en, Iran". earthquake.usgs.gov. USGS. Retrieved 4 August 2021.
  15. ^ "زمین لرزه ۶ آذر ۱۳۵۸ (۲۷ نوامبر ۱۹۷۹) کولی-بنیاباد" (in Persian). Institute of Engineering Seismology and Earthquake Engineering. Retrieved 4 August 2021.