1833 Bihar–Nepal Earthquake
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The 1833 Nepal–India earthquake occurred on August 26 at 22:58 local time (NPT). This earthquake had an estimated moment magnitude () of 7.6–7.9 and struck with an epicenter somewhere in or near the
Kathmandu Valley The Kathmandu Valley (), also known as the Nepal Valley or Nepa Valley (, Newar language, Nepal Bhasa: 𑐣𑐾𑐥𑐵𑑅 𑐐𑐵𑑅, नेपाः गाः), National Capital Area, is a bowl-shaped valley located in the Himalayas, Hima ...
. The earthquake caused major destruction in numerous towns and villages in Nepal, northern India, and Tibet. The earthquake was also felt in
Chittagong Chittagong ( ), officially Chattogram, (, ) (, or ) is the second-largest city in Bangladesh. Home to the Port of Chittagong, it is the busiest port in Bangladesh and the Bay of Bengal. The city is also the business capital of Bangladesh. It ...
,
Bangladesh Bangladesh, officially the People's Republic of Bangladesh, is a country in South Asia. It is the List of countries and dependencies by population, eighth-most populous country in the world and among the List of countries and dependencies by ...
. Despite the extent of the damage, the number of fatalities resulting from the earthquake was surprisingly low, at approximately 500. This was because 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 ev ...
was preceded by two smaller but intense
foreshock A foreshock is an earthquake that occurs before a larger seismic eventthe mainshockand 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 sequenc ...
s earlier that day, causing many residents to take refuge outside their homes.


Geology

The
Main Himalayan Thrust The Main Himalayan Thrust (MHT) is a décollement under the Himalaya Range. This thrust fault follows a northwest-southeast strike, reminiscent of an arc, and gently dips about 10 degrees towards the north, beneath the region. It is the large ...
is a
décollement Décollement () is a gliding plane between two rock masses, also known as a basal detachment fault. Décollements are a Deformation (geology), deformational structure, resulting in independent styles of deformation in the rocks above and below t ...
structure that defines the boundary 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 Eurasian Plate. This thrust fault is the source of most of Nepal's earthquakes. The earthquake of 1833 has been suggested by geologists to be a repeat of the 1344 earthquake, and the 2015 Gorkha earthquake was a repeat of the 1833 event. All of which failed to release all the strain that had been building over the past centuries thus was an incomplete rupture of the Main Himalayan Thrust. The décollement rupture area of the 1833 event is likely the same as in 2015, but closer to Kathmandu. Both earthquakes occurred along the MHT but did not rupture to the surface, thus, were
blind thrust earthquake A blind thrust earthquake occurs along a thrust fault that does not show signs on the Earth's surface, hence the designation "blind". Such faults, being invisible at the surface, have not been mapped by standard surface geological mapping. Sometim ...
s. Inferring from
isoseismal map In seismology, an isoseismal map is used to show Contour line, countour lines of equally felt seismic intensity, generally measured on the Modified Mercalli scale. Such maps help to identify earthquake epicenters, particularly where no seismometer ...
s prepared after the quake, researchers believe the earthquake was caused by an 80–120 km × 40 km section of the megathrust rupturing. The same fault patch that ruptured in 1833 would re-rupture again during the 8.0 1934 Bihar earthquake, as the 1833 event did little to release the elastic tension along the décollement. Very little is known about the
epicenter The epicenter (), epicentre, or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates. Determination The primary purpose of a ...
location of the earthquake due to the poor constrains in data. Researcher and seismologist
Nicholas Ambraseys Nicholas Neocles Ambraseys (19 January 1929 – 28 December 2012) was a Greek engineering seismologist. He was emeritus professor of engineering seismology and senior research fellow at Imperial College London. For many years Ambraseys was consi ...
determined the epicenter coordinates was . Another epicenter area located roughly 130 km west of the 1934 earthquake epicenter, at the eastern edge of a seismic gap has been favoured by many authors.


Earthquake

At about 6:00 pm, the first foreshock was felt in
Kathmandu Kathmandu () is the capital and largest city of Nepal, situated in the central part of the country within the Kathmandu Valley. As per the 2021 Nepal census, it has a population of 845,767 residing in 105,649 households, with approximately 4 mi ...
for 40 seconds, it was significant but not strong enough to cause any fatalities. Plants and trees were seen swaying from the crowns to their roots. The next foreshock occurred at 10:45 pm, which had similar effects like the one five hours earlier. These foreshocks would have a large influence on the number of casualties caused by the mainshock. Fifteen minutes later, another earthquake rocked the city. It was described in the beginning as gentle rocking, followed by some rumbling sounds. Shaking then escalated to a more violent characteristic; trees were seen bending, and houses ripped from their foundations. Horses and cattle escaped from their stalls, frightened by the earthquake. The earthquake was so strong that people found it difficult to walk, like those seen in footages of the 2015 earthquake. It lasted an approximate three minutes. Many terrified residents got to the ground and began to pray during the earthquake. In
Kathmandu Kathmandu () is the capital and largest city of Nepal, situated in the central part of the country within the Kathmandu Valley. As per the 2021 Nepal census, it has a population of 845,767 residing in 105,649 households, with approximately 4 mi ...
, the earthquake was assigned a modified
Mercalli intensity scale The Modified Mercalli intensity scale (MM, MMI, or MCS) measures the effects of an earthquake at a given location. This is in contrast with the seismic magnitude usually reported for an earthquake. Magnitude scales measure the inherent force or ...
rating of VIII (''Severe'') to X (''Extreme''). In an article published by The India Gazette on September 12 the same year, the earthquake was perceived as wave-like with long rolls and peaks, in a northeast and southwest direction. At
Chhapra Chhapra (ISO 15919, ISO: ''Chaparā'') is a city and headquarters of the Saran District in the Indian state of Bihar. It is situated near the junction of the Ghaghara River and the Ganges River. Chhapra grew in importance as a river-based mar ...
,
Bihar Bihar ( ) is a states and union territories of India, state in Eastern India. It is the list of states and union territories of India by population, second largest state by population, the List of states and union territories of India by are ...
, the mainshock was still strong enough to be felt even from Nepal. It shook houses and woke many residents from their sleep. Many people rushed out of their houses even as more strong shock rocked the city. Huge chunks of cornice and plasters fell from walls during the quake. Several native dwellings were reportedly destroyed, and at least three people died from house collapses. A massive fissure also tore through the ground some two miles from the city. The foreshocks were also distinctly felt in
Gorakhpur Gorakhpur is a city in the List of state and union territory capitals in India, Indian state of Uttar Pradesh, along the banks of the West Rapti River, Rapti river in the Purvanchal , Purvanchal region. It is situated 272 kilometres east of ...
,
Uttar Pradesh Uttar Pradesh ( ; UP) is a States and union territories of India, state in North India, northern India. With over 241 million inhabitants, it is the List of states and union territories of India by population, most populated state in In ...
, jolting many people from their sleep, including the Europeans settling in the area. Almost all the Europeans residing in an establishment ran out of their residences for fear that they would crumble. Tremors were still felt even 20 minutes later. The mainshock struck at just before midnight, described as more violent than earlier events, and as if being "seized by several hands and shaken violently backward and forwards". All the local residents in the city dashed out of their homes. The earthquake was so intense that standing was nearly impossible.


Aftershocks

An
aftershock In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in Epicenter, the same area of the Mainshock, main shock, caused as the displaced Crust (geology), crust adjusts to the effects of the main shock. Large earthq ...
sequence immediately followed after the mainshock, but it gradually decayed after persisting for several weeks. Strong aftershocks were felt on October 4, October 18, and November 26 of 1833. In 1835, a major aftershock struck the same region. The estimated magnitude of this aftershock is on the order of 6.5 or greater. Thirty-three years later, another large earthquake struck on May 23, 1866. Estimates of this magnitude range between 6.8 and 7.4, too small to cause any surface ruptures. Its epicenter location remains uncertain although some geologists suggest it was in the same location as the
May 2015 Nepal earthquake A major earthquake occurred in Nepal on 12 May 2015 at 12:50 pm local time (07:05 UTC) with a moment magnitude of 7.2–7.3, southeast of Kodari. The epicenter was on the border of Dolakha and Sindhupalchowk, two districts of Nepal. T ...
, or it might be a deeper event like that of the Bihar earthquake in 1988.


Impact

The earthquake was felt over an area roughly 1 million km2 in Nepal, northern India, and southern Tibet. Large
landslides Landslides, also known as landslips, rockslips or rockslides, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, mudflows, shallow or deep-seated slope failures and debris flows. Landslide ...
, rockfalls and avalanches in the mountainous region destroyed over 4,600 homes and temples. The two foreshocks occurring a few hours to minutes before the larger quake may have greatly reduced the death toll. Residents were driven out of their homes and dwellings due to panic caused by the two shocks. Had the two foreshocks not happened, many residents would have been killed. At least 30% or more of all homes in northern Nepal and the southern
Tibet Tibet (; ''Böd''; ), or Greater Tibet, is a region in the western part of East Asia, covering much of the Tibetan Plateau and spanning about . It is the homeland of the Tibetan people. Also resident on the plateau are other ethnic groups s ...
region were totally destroyed. In the
Kathmandu Valley The Kathmandu Valley (), also known as the Nepal Valley or Nepa Valley (, Newar language, Nepal Bhasa: 𑐣𑐾𑐥𑐵𑑅 𑐐𑐵𑑅, नेपाः गाः), National Capital Area, is a bowl-shaped valley located in the Himalayas, Hima ...
, 400 buildings crumpled to the ground, burying many occupants residing in them. One of the two towers of the
Dharahara Dharahara or ''Bhimsen Stambha'' (; or ), is a tower at the centre of Sundhara, Kathmandu, Nepal. It was first built in 1832 by ''Mukhtiyar'' (equivalent to Prime Minister) Bhimsen Thapa under the commission of Queen Lalit Tripurasundari and ...
, built by
Bhimsen Thapa Bhimsen Thapa ( (August 1775 – 29 July 1839)) was a Nepalese statesman who served as the ''Mukhtiyar'' (equivalent to prime minister) and de facto ruler of Nepal from 1806 to 1837. He is widely known as the List of Prime Ministers of Nepal, l ...
collapsed completely and was never rebuilt. The other tower suffered minor damage and was repaired shortly after. The new tower stood over the city until 1934 when the magnitude 8.0 earthquake would knock it down again. The other was partially damaged and quickly restored, only to be destroyed once again during the 1934 Bihar earthquake. The home of Matabarsing Thapa, was completely destroyed, and the garden houses belonging to
Bhimsen Thapa Bhimsen Thapa ( (August 1775 – 29 July 1839)) was a Nepalese statesman who served as the ''Mukhtiyar'' (equivalent to prime minister) and de facto ruler of Nepal from 1806 to 1837. He is widely known as the List of Prime Ministers of Nepal, l ...
became unfit for occupancy. In all, a total of 18,000 buildings were totally wiped out, with over 4,000 having collapsed in the Kathmandu Valley region. In the town of
Bhaktapur Bhaktapur (Nepali language, Nepali and Sanskrit: भक्तपुर, ; "City of Devotees"), known locally as Khwopa (Nepal Bhasa: , ) and historically called Bhadgaon, is a city in the east corner of the Kathmandu Valley in Nepal located abou ...
(then Bhatgaon), east of the Kathmandu Valley, at least 200 individuals were killed, making it the worst affected area outside the valley. One quarter (25%) to 70% of the town suffered major destruction, including at least 2,000 homes and six to eight temples. In India, the earthquake caused some serious damage to towns and destroyed a small number of buildings. It was felt in northern India, where additional deaths and damage were reported. Damage there was generally less widespread, with fewer deaths recorded. The capital of
Uttar Pradesh Uttar Pradesh ( ; UP) is a States and union territories of India, state in North India, northern India. With over 241 million inhabitants, it is the List of states and union territories of India by population, most populated state in In ...
,
Lucknow Lucknow () is the List of state and union territory capitals in India, capital and the largest city of the List of state and union territory capitals in India, Indian state of Uttar Pradesh and it is the administrative headquarters of the epon ...
, felt four distinct shocks with the last two causing homes to creak, and lamps to swing about. The shaking caused animals including birds, elephants, and snakes to behave unusually. Residents of the city ran out of their homes, fearing it would collapse on them, and began to pray. The same effects were observed in other parts of India, where many people and animals became frightened.


See also

*
List of earthquakes in Nepal Lying in one of the most seismically active regions of the world, Nepal has a long history of earthquakes. The first documented earthquake event in the country dates back to 7 June 1255, during the reign of King Abhaya Malla. The quake, measuring 7 ...
*
List of earthquakes in India The Indian subcontinent has a history of earthquakes. The reason for the intensity and high frequency of earthquakes is the Indian plate driving into Asia at a rate of approximately 47 mm/year. The following is a list of major earthquakes whic ...
*
List of historical earthquakes Historical earthquakes is a list of significant earthquakes known to have occurred prior to the early 20th century. As the events listed here occurred before routine instrumental recordings, they rely mainly on the analysis of written sources, ...


References

{{DEFAULTSORT:Bihar-Nepal earthquake Earthquakes in Nepal Earthquakes in India Earthquakes in Tibet 1833 earthquakes Natural disasters in Bihar Buried rupture earthquakes 1833 in India 1833 in Nepal 1830s disasters in Asia