The 1983 Hindu Kush earthquake occurred south of

Fayzabad, Badakhshan Fayzabad also spelled Feyzabad or Faizabad () is a city in northeastern Afghanistan, with a population of around 39,555 people. It is the provincial capital and largest city of Badakhshan province. It is situated in Fayzabad district and is at a ...

in northeast

Afghanistan Afghanistan, officially the Islamic Emirate of Afghanistan, is a landlocked country located at the crossroads of Central Asia and South Asia. It is bordered by Pakistan to the Durand Line, east and south, Iran to the Afghanistan–Iran borde ...

at 03:52 PST on December 31, 1983, near the border with

Pakistan Pakistan, officially the Islamic Republic of Pakistan, is a country in South Asia. It is the List of countries and dependencies by population, fifth-most populous country, with a population of over 241.5 million, having the Islam by country# ...

and the

USSR The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

(now

Tajikistan Tajikistan, officially the Republic of Tajikistan, is a landlocked country in Central Asia. Dushanbe is the capital city, capital and most populous city. Tajikistan borders Afghanistan to the Afghanistan–Tajikistan border, south, Uzbekistan to ...

). Striking 214.5 km beneath the

Hindu Kush The Hindu Kush is an mountain range in Central Asia, Central and South Asia to the west of the Himalayas. It stretches from central and eastern Afghanistan into northwestern Pakistan and far southeastern Tajikistan. The range forms the wester ...

mountains, the

moment magnitude The moment magnitude scale (MMS; denoted explicitly with or Mwg, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. was defined in a 1979 paper ...

7.4 quake affected three countries, killing at least 26 people and injuring several hundred.

Tectonic setting

The Afghanistan-Pakistan-Tajikistan border region lies within the broad zone of ongoing crustal deformation caused by

continental collision In geology, continental collision is a phenomenon of plate tectonics that occurs at Convergent boundary, convergent boundaries. Continental collision is a variation on the fundamental process of subduction, whereby the subduction zone is destroy ...

between the

Indian plate The Indian plate (or India plate) is or was a minor tectonic plate straddling the equator in the Eastern Hemisphere. Originally a part of the ancient continent of Gondwana, the Indian plate broke away from the other fragments of Gondwana an ...

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 earthquake An intraplate earthquake occurs in the ''interior'' of a Plate tectonics, tectonic plate, in contrast to an interplate earthquake on the ''boundary'' of a tectonic plate. They are relatively rare compared to the more familiar interplate earthqu ...

s. Many large greater than magnitude 7.0 have been observed in the

, all with similar epicenters, with an approximate periodicity of about 10–15 years. These events have

reverse fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic f ...

focal mechanism The focal mechanism of an earthquake describes the Fault (geology)#Slip.2C heave.2C throw, deformation in the Hypocenter, source region that generates the seismic waves. In the case of a Fault (geology), fault-related event, it refers to the ori ...

s, 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. 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.

Earthquake

The most recent large event of this type was the

October 2015 Hindu Kush earthquake The October 2015 Hindu Kush earthquake was a magnitude 7.5 earthquake that struck South Asia on 26 October 2015, at 13:39 AFT (14:09 PKT; 14:39 IST; 09:09 UTC) with the epicenter 45 km north of Kuran wa Munjan, Afghanistan, at a depth ...

which killed over 300 people. The earthquake of 1983, together with that of 1993,

2002 The effects of the September 11 attacks of the previous year had a significant impact on the affairs of 2002. The war on terror was a major political focus. Without settled international law, several nations engaged in anti-terror operation ...

, and 2015 occurred in close proximity with each other. Events like these are considered an "earthquake next". The focal mechanism according to the

U.S. Geological Survey The United States Geological Survey (USGS), founded as the Geological Survey, is an agency of the U.S. Department of the Interior whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on March ...

indicated intermediate-depth reverse faulting. The seismogenic fault beneath the Hindu Kush is thought to have produced four magnitude 7.3–7.5 earthquakes between 1949 and 2015, and two 7.0 events in 1974 and 1993. The magnitude 7.3–7.5 earthquakes had an estimated 1.2 meters, and 0.7 meters for the 7.0 earthquakes, resulting in a total displacement of 6.2 meters along the same fault through 1949 and 2015, distributed across six earthquakes. Vertical necking or stretching of the rapidly moving (10 cm/yr) downgoing slab in the vicinity of the source fault encourages a high slip rate of 9.6 cm/year. The estimated slip rate is much faster than the 1 cm/yr convergent rate at the surface. Waveform inversion using the

Bayesian information criterion In statistics, the Bayesian information criterion (BIC) or Schwarz information criterion (also SIC, SBC, SBIC) is a criterion for model selection among a finite set of models; models with lower BIC are generally preferred. It is based, in part, on ...

revealed the earthquake consisted of two subevents with the latter about 20 km away from the first subevent. The first event occurred near the hypocenter along the fault. It's estimated that the latter subevent released seven times the

seismic moment Seismic moment is a quantity used by seismologists to measure the size of an earthquake. The scalar seismic moment M_0 is defined by the equation M_0=\mu AD, where *\mu is the shear modulus of the rocks involved in the earthquake (in pascal (unit) ...

of the former.

Other events

Two years after the 1983 quake, the Hindu Kush region was hit with another magnitude 7.4 quake. It struck with an epicenter 30 km southwest of the 1983 event at 98.7 km beneath the mountains. Five people died and 38 were injured in the

Chitral Chitral () is a city situated on the Kunar River, Chitral River in northern area of Khyber Pakhtunkhwa province of Pakistan. It serves as the capital of the Lower Chitral District, and was previously the capital of Chitral District, and before ...

and

Swat A SWAT (''Special Weapons and Tactics'') team is a generic term for a police tactical unit within the United States, though the term has also been used by other nations. SWAT units are generally trained, equipped, and deployed to res ...

districts of Pakistan. That quake triggered rockslides and

avalanches An avalanche is a rapid flow of snow down a Grade (slope), slope, such as a hill or mountain. Avalanches can be triggered spontaneously, by factors such as increased precipitation or snowpack weakening, or by external means such as humans, othe ...

throughout the Hindu Kush and Himalaya region. It had a maximum intensity of VIII (''Severe'') felt at

Khorog Khorog ( ), also Khorugh ( ) or Kharagh ( ), is the capital of Gorno-Badakhshan, Tajikistan. It is also the capital of the Shughnon District of Gorno-Badakhshan. It has a population of 30,500 (2020 ). Khorog is above sea level in the Pamir Mou ...

and Qurgonteppa, USSR. The earthquake was also felt strongly at

New Delhi New Delhi (; ) is the Capital city, capital of India and a part of the Delhi, National Capital Territory of Delhi (NCT). New Delhi is the seat of all three branches of the Government of India, hosting the Rashtrapati Bhavan, New Parliament ...

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

Impact

A total of 26 people died; 12 in

Kabul Kabul is the capital and largest city of Afghanistan. Located in the eastern half of the country, it is also a municipality, forming part of the Kabul Province. The city is divided for administration into #Districts, 22 municipal districts. A ...

and Samangan, Afghanistan, and 14 at

Peshawar Peshawar is the capital and List of cities in Khyber Pakhtunkhwa by population, largest city of the Administrative units of Pakistan, Pakistani province of Khyber Pakhtunkhwa. It is the sixth most populous city of Pakistan, with a district p ...

, Pakistan. Many died or were injured when their homes collapsed during their sleep. Several hundred people were injured in Pakistan and 483 were reported in Afghanistan. Eight members of one family were injured in Lahore. Damage was also reported in the USSR, now Tajikistan.

References

{{DEFAULTSORT:Hindu Kush earthquake, 1983 1983 earthquakes Earthquakes in Afghanistan Earthquakes in Pakistan Earthquakes in Tajikistan 1983 in Afghanistan 1983 in Pakistan 1983 in the Soviet Union 1983 disasters in Asia Earthquakes in the Soviet Union December 1983 in Asia

Tectonic setting

Earthquake

Other events

Impact

See also

References