1991 Hindu Kush earthquake

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1991 Hindu Kush earthquake
1991 Hindu Kush earthquake is located in Afghanistan
1991 Hindu Kush earthquake
UTC time1991-01-31 23:03:33
ISC event346020
USGS-ANSSComCat
Local dateFebruary 1, 1991 (1991-02-01)
Local time03:33:33 AFT
04:03:33 PST
Magnitude6.9 Mw[1]
Depth142.4 km
Epicenter35°59′35″N 70°25′23″E / 35.993°N 70.423°E / 35.993; 70.423Coordinates: 35°59′35″N 70°25′23″E / 35.993°N 70.423°E / 35.993; 70.423
Areas affectedAfghanistan
Pakistan
Max. intensityVII (Very strong)[2]
Casualties848 dead, 200+ injured[3]

The 1991 Hindu Kush earthquake occurred northeast of Kabul, Afghanistan. It was an intermediate-depth earthuake with a hypocenter 142.4 km beneath the Hindu Kush mountains. The quake measured 6.9 on the moment magnitude scale, and affected neighbouring Pakistan and the USSR.[1] At least 848 people were killed in both countries and damage was estimated at $26 million USD ($53.2 million in 2022).[3]

Background[]

The Afghanistan-Pakistan-Tajikistan border region lies within the broad zone of ongoing crustal deformation caused by continental collision between the Indian Plate and the Eurasian Plate. The area is seismically active, particularly as a result of faulting at just over 200 km depth within the downgoing slab, producing intraplate earthquakes. Many large greater than magnitude 7.0 have been observed in the Hindu Kush, all with similar epicenters, with an approximate periodicity of about 10–15 years. These events have reverse fault focal mechanisms, which for the near-vertical slab indicates active extension. It has been proposed that these earthquakes are a result of "necking" of the downgoing slab, a process that may eventually lead to break-off.[4]

Smaller shallow focus earthquakes are also observed in the region, particularly associated with north–south trending zones of right lateral strike-slip, such as the Chaman Fault, with an increasing degree of shortening to the north, together accommodating the highly oblique convergence between the Indian Plate and the Eurasian Plate.[5]

Damage and casualties[]

An estimated 545 people died in Afghanistan's Konar, Nangarhar and Badakhshan provinces, when homes were destroyed. Another 300 people died in Azad Kashmir, Pakistan. Thousands of houses in Malakand, Chitral, and Peshawar suffered severe damage. Three people died from heart attacks in Khorog, Tajikistan. Landslides were also observed.[3]

See also[]

References[]

  1. ^ a b "M 6.9 - 77 km NW of P?r?n, Afghanistan". earthquake.usgs.gov. U.S. Geological Survey. Retrieved 25 December 2021.
  2. ^ International Seismological Centre. Event Bibliography. Thatcham, United Kingdom. [Event 346020].
  3. ^ a b c "Significant Earthquake Information". ngdc.noaa.gov. NOAA National Centers for Environmental Information. Retrieved 25 December 2021.
  4. ^ Zhan, Z.; Kanamori, H. (2016). "Recurring large deep earthquakes in Hindu Kush driven by a sinking slab". Geophysical Research Letters. 43 (14): 7433–7441. doi:10.1002/2016GL069603.
  5. ^ Ambraseys, N.N.; Bilham, R. (2003). "Earthquakes in Afghanistan". Seismological Research Letters. 74 (2): 107–123. doi:10.1785/gssrl.74.2.107. S2CID 130945532.
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