The 1980 Nepal earthquake devastated the Nepal–India border region on the evening of July 29. The epicenter of the 6.6 earthquake was located in

Nepal Nepal (; ne, नेपाल ), formerly the Federal Democratic Republic of Nepal ( ne, सङ्घीय लोकतान्त्रिक गणतन्त्र नेपाल ), is a landlocked country in South Asia. It is mai ...

, northwest of

Khaptad National Park Khaptad National Park is a protected area in the Far-Western Region, Nepal that was established in 1984. Stretching over the four districts of Bajhang, Bajura, Achham and Doti it covers an area of and ranges in elevation from to . History Kh ...

. At least 200 people died and 5,600 were injured in the disaster. Extensive damage occurred on both sides of the border, amounting to 245 million

USD The United States dollar (symbol: $; code: USD; also abbreviated US$ or U.S. Dollar, to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the official ...

(828.9 million in 2022).

Tectonic setting

The Himalaya is located at the

convergent boundary A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more Plate tectonics, lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can ...

where active convergence leads to

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

. The India and Eurasian plates began colliding approximately 50 million years ago when the

Tethys Ocean The Tethys Ocean ( el, Τηθύς ''Tēthús''), also called the Tethys Sea or the Neo-Tethys, was a prehistoric ocean that covered most of the Earth during much of the Mesozoic Era and early Cenozoic Era, located between the ancient continents ...

closed. The

Main Himalayan Thrust The Main Himalayan Thrust (MHT) is a décollement under the Himalaya Range. This thrust fault follows a NW-SE strike, reminiscent of an arc, and gently dip towards the north, beneath the region. It is the largest active continental megathrust f ...

(MHT), a decollement structure, defines the boundary between the

Indian Plate The Indian Plate (or India Plate) is 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 , began mov ...

and

Eurasian Plate The Eurasian Plate is a tectonic plate that includes most of the continent of Eurasia (a landmass consisting of the traditional continents of Europe and Asia), with the notable exceptions of the Indian subcontinent, the Arabian subcontinent and ...

. The convergent zone also contains three other major faults; the Main Boundary Thrust (MBT),

Main Central Thrust The Main Central Thrust is a major geological fault where the Indian Plate has pushed under the Eurasian Plate along the Himalaya. The fault slopes down to the north and is exposed on the surface in a NW-SE direction (strike). It is a thrust fault ...

(MCT) and

South Tibetan Detachment The South Tibetan Detachment is one of the major faults in the Himalaya Mountains. Background Understanding the formation of the Himalayan mountains has been a goal of structural geologists for a long time. Many of the problems and disagreements ...

(STD). At the surface, the Main Himalayan Thrust propagates along the

Main Frontal Thrust The Main Frontal Thrust (MFT), also known as the Himalayan Frontal Thrust (HFT) is a geological fault in the Himalayas that defines the boundary between the Himalayan foothills and Indo-Gangetic Plain. The fault is well expressed on the surfac ...

. These faults runs for approximately 2,300 km in an east-west direction, parallel to the southern foothills of the

Lower Himalayan Range The Lower Himalayan Range ( ne, पर्वत शृङ्खला parbat shrinkhalā) – also called the Middle Himalayas or Lesser Himalayas or Himachal – is a major east–west mountain range with elevations 3,700 to 4,500 m (12,000 to ...

from

Assam Assam (; ) is a state in northeastern India, south of the eastern Himalayas along the Brahmaputra and Barak River valleys. Assam covers an area of . The state is bordered by Bhutan and Arunachal Pradesh to the north; Nagaland and Manipur ...

, through

, and into

Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...

. This major

thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If ...

dips to the north, beneath the Himalaya at a shallow angle. It is the source of most of Himalayan earthquakes. Earthquakes on the convergent boundary are megathrust events that repeat every few centuries. Large Himalayan earthquakes including those in 1505, 1934 and 1950 with magnitudes of 8.0 to 8.9 were the result of rupturing the MHT. These events generated surface ruptures by breaching the surface via the Main Frontal Thrust. The

Uttarakhand Uttarakhand ( , or ; , ), also known as Uttaranchal ( ; the official name until 2007), is a state in the northern part of India. It is often referred to as the "Devbhumi" (literally 'Land of the Gods') due to its religious significance and ...

and west Nepal segment of the MHT was responsible for the 7.8 1803 Garhwal earthquake as well as two smaller but deadly events in 1991 and 1999. Deadly earthquakes occurred in 1966, and an 7.0 struck the same region in 1916.

Earthquake

The earthquake occurred as the result of shallow

ing on the MHT boundary fault, between the MCT and the MBT. The

rupture Rupture may refer to: General * Rupture (engineering), a failure of tough ductile materials loaded in tension Anatomy and medicine * Abdominal hernia, formerly referred to as "a rupture" * Achilles tendon rupture * Rupture of membranes, a "wate ...

mechanism occurred on two separate fault planes; the latter corresponding to thrust faulting. A small right-lateral strike-slip component was measured as well.

Damage and casualties

The

mainshock In seismology, the mainshock is the largest earthquake in a sequence, sometimes preceded by one or more foreshocks, and almost always followed by many aftershocks. Foreshock A foreshock is an earthquake that occurs before a larger seismic eve ...

was preceded by a strong 5.7

foreshock A foreshock is an earthquake that occurs before a larger seismic event (the mainshock) and is related to it in both time and space. The designation of an earthquake as ''foreshock'', ''mainshock'' or aftershock is only possible after the full se ...

almost three hours prior. Severe shaking lasted 20 seconds during the mainshock. The death toll would have been higher if not for the foreshock which had residents on high alert, and driven them out of their homes. A total of 13,258 homes were destroyed, making at least 30,000 homeless. The greatest damage was situated in a narrow zone between northwest Darchula and southeast Bajhang. An inspection after the earthquake found that tall buildings were the most damaged. Houses with heavy roofs made of

slate Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. It is the finest grained foliated metamorphic rock. ...

were also found to be greatly affected. The report concluded that weak foundations and haphazard construction practices were responsible for the extensive damage observed. In the village of Moribagad, damage was minimal. The limited damage was, according to residents, because they followed the rules of their goddess. The rule stated that residents must not build a house with more than two floors, as a middle floor is forbidden. The next rule forbids slate roofs which were heavy, hence residents constructed lightweight

thatch Thatching is the craft of building a roof with dry vegetation such as straw, water reed, sedge (''Cladium mariscus''), rushes, heather, or palm branches, layering the vegetation so as to shed water away from the inner roof. Since the bulk of ...

roofs. The

Mahakali Mahakali () is the Hindu goddess of time and death in the goddess-centric tradition of Shaktism. Similar to Kali, Mahakali is a fierce goddess associated with universal power, time, life, death, and both rebirth and liberation. She is the cons ...

and

Seti Zone Seti ( ne, सेती अञ्चल) was one of the fourteen zones located in the Far-Western Development Region of Nepal. Dhangadhi in the Terai is the major city of Seti Zone; headquarters are in Dipayal-Silgadhi. As of 2015, Nepal disco ...

s suffered major impacts. Three districts in the zone;

Bajhang Bajhang District ( , a part of Sudurpashchim Province, is one of the seventy-seven districts of Nepal. The district, with Chainpur, that is part of Jaya Prithvi Municipality, as its district headquarters, covers an area of and has a populatio ...

Baitadi Khalanga or Baitadi Khalanga is a town and seat of Baitadi District in the Sudurpashchim Province of western Nepal. At the time of the 1991 Nepal census The 1991 Nepal census was a widespread national census conducted by the Nepal Central Bureau ...

, and

Bajura Bajura District ( ne, बाजुरा जिल्ला ), a part of Sudurpashchim Province, is one of the seventy-seven districts of Nepal. The district, with Martadi (today part of Badimalika municipality) as its district headquarter ...

were the most affected. Up to 40 people died in the districts and 2,000 wre injured. An additional 5,000 families were left without homes. Several major towns in

Darchula District Darchula District ( ne, दार्चुला जिल्ला , a part of Sudurpashchim Province, is one of the nine districts of province and one of seventy-seven districts of Nepal. The district, with Khalanga ( Mahakali Municipality) ...

were obliterated. At least 90 schools were totally destroyed in Bajhang. The Rastriya Samachar Samiti (RSS) reported 12 district official and 21 village buildings, as well as 65 temples were also destroyed. The cost of damage in the district was $ 10.3 million. Telecommunication services were affected, as did army barracks and police stations suffer damage. The earthquake occurred during the monsoon season which further affected communications and transport services in the aftermath due to

landslide Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated grade (slope), slope failures, mudflows, and debris flows. Landslides occur in a variety of ...

References

External links

* {{Disasters in Uttarakhand 1980 earthquakes Disasters in Uttarakhand Earthquakes in Nepal Earthquakes in India Sudurpashchim Province History of Uttarakhand (1947–present) July 1980 events in Asia 1980 in Nepal 1980 in India Uttarkashi district 1980 disasters in India 1980 disasters in Nepal

Tectonic setting

Earthquake

Damage and casualties

See also

References

External links