1992 Kohat earthquake
1992 Kohat earthquake is located in Pakistan
1992 Kohat earthquake
UTC time1992-05-20 12:20:32
ISC event292331
USGS-ANSSComCat
Local dateMay 20, 1992
Local time17:20:32
MagnitudeMw 6.3
Depth16.3 km
Epicenter33°22′37″N 71°19′01″E / 33.377°N 71.317°E / 33.377; 71.317
Max. intensityVII (Very strong)
Casualties36 dead, 100 injured

The 1992 Kohat earthquake struck Khyber Pakhtunkhwa Province in Pakistan on May 20. The Mw  6.3 earthquake inflicted significant damage in the nearby city Kohat. An estimated 36 people died and 100 were injured in the Peshawar and Kohat districts.[1] Four-hundred (400) homes were wiped out, affecting 2,100 residents in the region.[2]

Tectonic setting

Pakistan is directly influenced by the ongoing oblique convergence between the Indian Plate and Eurasian Plate. Along the northern margin of the India-Eurasia convergent boundary is the Main Himalayan Thrust which accommodates north-south continental collision. Thrust faulting in the Hindu Kush and Himalaya region is the direct result of the plate interaction. In the Balochistan region, the convergence is highly oblique, involving the large Chaman Fault; a left-lateral strike-slip structure. While a large portion of the boundary is accommodated by strike-slip faulting, the region also hosts the Sulaiman fold and thrust belt.[3] Large thrust earthquakes including the 1934 Nepal–India earthquake were the direct result of the plate interaction. The 2005 Kashmir earthquake occurred near the vicinity of the Main Himalayan Thrust.

Earthquake

The earthquake occurred in an unusual region because the western boundary of the India-Eurasia plate boundary was thought to be aseismic; unable to produce earthquakes. The India Plate slips beneath the Kohat Plateau along an almost horizontal decollement at a rate of 2 mm/yr. Slips occur aseismically due to the presence of salt, which acts as a lubricant between the plateau and the underlying bedrock, reducing friction during slip and avoiding earthquakes.[4]

At the location of the earthquake, the loss of salt on the decollement led to increased friction and seismic strain. Seismic strain is accumulated and overcame during earthquakes. The earthquake rupture covered a 80 km2 on a near-horizontal decollement thrust fault. The event led to the conclusion that slip on the decollement occurs both aseismically and seismically. It is the largest ever recorded in the Kohat Plateau.[5]

See also

References

  1. ↑ "M 6.3 - 2 km WSW of Lachi, Pakistan". earthquake.usgs.gov. U.S. Geological Survey. Retrieved 14 October 2021.
  2. ↑ "Significant Earthquake Information". ngdc.noaa.gov. NOAA National Centers for Environmental Information. Retrieved 14 October 2021.
  3. ↑ Kirsty Reynolds; Alex Copley; Ekbal Hussain (2015). "Evolution and dynamics of a fold-thrust belt: the Sulaiman Range of Pakistan". Geophysical Journal International. 201 (2): 683–710. doi:10.1093/gji/ggv005.
  4. ↑ Gammon, Crystal (16 January 2012). "Rare Caterpillar-like Horizontal Earthquake Discovered". Live Science. Retrieved 14 October 2021.
  5. ↑ S. P. Satyabala; Zhaohui Yang; Roger Bilham (2012). "Stick–slip advance of the Kohat Plateau in Pakistan". Nature Geoscience. 5 (2): 147–150. Bibcode:2012NatGe...5..147S. doi:10.1038/ngeo1373. S2CID 92989973.
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