View source for 1950 Assam Tibet earthquake

{{Infobox earthquake
| title = 1950 Assam–Tibet earthquake
| map2 = {{Location map | Tibetan Plateau
 | label=
 | lat=28.36
 | long=96.45
 | mark=Bullseye1.png
 | marksize=40
 | position=top
 | width= 250
 | float=right
 | caption=}}
| local-date = {{start-date|August 15, 1950}}
| local-time = 7:39 pm IST
| timestamp = 1950-08-15 14:09:34
| anss-url = official19500815140934_30
| isc-event = 895681
| magnitude = 8.6 {{M|w|link=y}} <ref name=ISC-GEM/>
| depth = {{convert|15|km|abbr=on}} <ref name=ISC-GEM/>
| location = {{coord|28.36|N|96.45|E}} <ref name=ISC-GEM/>
| type = [[Fault (geology)#Strike-slip faults|Strike-slip]]<ref name=USGS/>
| countries affected = [[Tibet (1912–51)|Tibet]], [[Assam]]
| intensity = {{MMI|XI}}<ref name=PAGER-CAT/>
| tsunami = 
| aftershocks = 
| casualties = 4,800
| fault = [[Main Himalayan Thrust]]
| foreshocks = 
| landslide = 
| pgv = 
| pga = 
| damages = 
| affected = 
| name = 
| duration = 
| map_caption = 
| map_alt = 
| map = 
| caption = 
| alt = 
| image = 
| citations = 
}}
The '''1950 Assam–Tibet earthquake''',<ref name="earthquake.usgs.gov">{{cite web|url=https://earthquake.usgs.gov/earthquakes/world/events/1950_08_15.php |title=Historic Earthquakes, Assam - Tibet |publisher=[[United States Geological Survey]] |access-date=January 24, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20161110034028/http://earthquake.usgs.gov/earthquakes/world/events/1950_08_15.php |archive-date=November 10, 2016 }}</ref> also known as the '''Assam earthquake''',<ref name="earthquake.usgs.gov"/> occurred on 15 August and had a [[Moment magnitude scale|moment magnitude]] of 8.6. The epicentre was located in the [[Mishmi Hills]], known in Chinese as the Qilinggong Mountains ({{lang|zh|祁灵公山}}), south of the [[Kangri Garpo]] and just east of the [[Himalayas]] in the [[North-East Frontier Agency]] part of [[Assam]], [[India]].  This area, south of the [[McMahon Line]] and now known as [[Arunachal Pradesh]], is today disputed between [[China]] and India.

Occurring on a Tuesday evening at 7:39 pm [[Indian Standard Time]], the [[earthquake]] was destructive in both [[Assam]] (India) and [[Tibet]] (China), and approximately 4,800 people were killed.  The earthquake is notable as being the largest recorded quake caused by [[continental collision]] rather than [[subduction]], and is also notable for the loud noises produced by the quake and reported throughout the region.

== Geology ==
In an attempt to further uncover the seismic history of [[Northeast India]], field studies were conducted by scientists with the [[National Geophysical Research Institute]] and [[Institute of Physics, Bhubaneswar]]. The study discovered signs of [[soil liquefaction]] including [[sill (geology)|sill]]s and [[sand volcano]]es inside of at least twelve [[trench]]es in [[alluvial fan]]s and on the [[Dihing River|Burhi Dihing River Valley]] that were formed by past [[seismic activity]]. [[Radiocarbon dating]] identified the deposits at roughly 500 years old, which would correspond with a recorded earthquake in 1548.<ref>{{cite journal|title=The great 1950 Assam Earthquake revisited: Field evidences of liquefaction and search for paleoseismic events|author=Reddy, D.V.  |author2=Nagabhushanam, P. |display-authors=etal |journal=[[Tectonophysics (journal)|Tectonophysics]]|date=September 2009|volume=474|issue=3|pages=463–472|bibcode = 2009Tectp.474..463R |doi = 10.1016/j.tecto.2009.04.024 }}</ref>

==Earthquake==
The earthquake occurred in the rugged mountainous areas between the [[Himalayas]] and the [[Hengduan Mountains]].  The earthquake was located just south of the [[McMahon Line]] between India and Tibet, and had devastating effects in both regions.  Today this area is claimed as part of [[Zayü County|Zayü]] and [[Mêdog County|Mêdog]] Counties in the [[Tibet Autonomous Region]] by China, and as part of [[Lohit District]] in [[Arunachal Pradesh]] by India.  This great earthquake has a calculated magnitude of 8.6 and is regarded as one of the most important since the introduction of [[Seismological observatory|seismological observing stations.]]

It was the sixth largest earthquake of the 20th century.<ref>{{cite web|url=https://earthquake.usgs.gov/earthquakes/world/10_largest_world.php |title=Largest Earthquakes in the World Since 1900 |publisher=[[United States Geological Survey]] |date=September 20, 2011 |access-date=December 17, 2010 |archive-url=https://web.archive.org/web/20101107224716/http://earthquake.usgs.gov/earthquakes/world/10_largest_world.php |archive-date=7 November 2010 |url-status=dead }}</ref>  It is also the largest known earthquake to have not been caused by an oceanic [[subduction]]. Instead, this quake was caused by two [[Continental collision|continental plates colliding]].

[[Aftershock]]s were numerous; many of them were of magnitude 6 and over and well enough recorded at distant stations for reasonably good [[epicentre]] location. From such data the Indian Seismological Service established an enormous geographical spread of this activity, from about 90 deg to 97 deg east longitude, with the epicentre of the great earthquake near the eastern margin.{{citation needed|date=September 2017}}

==Impact==
The 1950 Assam–Tibet earthquake had devastating effects on both Assam and Tibet.  In Assam, 1,526 fatalities were recorded<ref>{{cite web| url=http://www.ngdc.noaa.gov/nndc/struts/results?eq_0=3950&t=101650&s=13&d=22,26,13,12&nd=display|title=Significant Earthquake INDIA-CHINA | publisher=[[National Geophysical Data Center]]| date=August 15, 1950 | access-date=November 24, 2016}}</ref> and another 3,300 were reported in Tibet for a total of approximately 4,800 deaths.{{citation needed|date=October 2020}}

Alterations of relief were brought about by many rock falls in the Mishmi Hills and surrounding forested regions. In the Abor Hills, 70 villages were destroyed with 156 casualties due to landslides. Landslides blocked the tributaries of the [[Brahmaputra]]. In the [[Dibang Valley]], a [[Landslide dam|landslide lake]] burst without causing damage, but another at [[Subansiri River]] opened after an interval of 8 days and the wave, {{cvt|7|m|ft}} high, submerged several villages and killed 532 people.{{citation needed|date=September 2017}}

The shock was more damaging in Assam, in terms of property loss, than the [[1897 Assam earthquake|earthquake of 1897]]. In addition to the extreme shaking, there were floods when the rivers rose high after the earthquake bringing down sand, mud, trees, and all kinds of debris. Pilots flying over the meizoseismal area reported great changes in topography. This was largely due to enormous [[landslides]], some of which were photographed.

In Tibet, [[Heinrich Harrer]] reported strong shaking in [[Lhasa]] and loud cracking noises from the earth.<ref>{{cite book|last1=Harrer|first1=Heinrich|title=Seven Years in Tibet|date=1953|publisher=Putnam|ref=seven years}}</ref>  Aftershocks were felt in Lhasa for days.  In Rima, Tibet (modern-day [[Zayü]] Town), [[Frank Kingdon-Ward]], noted violent shaking, extensive slides, and the rise of the streams.{{citation needed|date=September 2017}} Helen Myers Morse, an American missionary living in Putao, northern [[Burma]] at the time, wrote letters home describing the main shake, the numerous aftershocks, and of the noise coming out of the earth.<ref>{{cite book|last1=Myers Morse|first1=Helen|title=Once I Was Young|date=2003|location=Terre Haute, Indiana|pages=167–171}}</ref>

One of the more westerly aftershocks, a few days later, was felt more extensively in Assam than the main shock. This led certain journalists to the belief that the later shock was 'bigger' and must be the greatest earthquake of all time. This is a typical example of the confusion between the essential concepts of magnitude and intensity. The extraordinary sounds heard by Kingdon-Ward and many others at the times of the main earthquake have been specially investigated. [[Seiche]]s were observed as far away as Norway and England. (p.&nbsp;63–64.)

== Future threat ==
An article in ''[[Science (magazine)|Science]]'', published in response to the [[2001 Bhuj earthquake]], calculated that 70 percent of the [[Himalayas]] could experience an extremely powerful earthquake. The prediction came from research of the historical records from the area as well as the presumption that since the 1950 Medog earthquake enough slippage has taken place for a large earthquake to occur.<ref name=State>{{cite news|title=Quake in Himalayas: US & Indian experts differ|work=[[The Statesman (India)|The Statesman]]|date=September 6, 2001}}</ref>  In 2015, the Himalayas were hit by a [[April 2015 Nepal earthquake|7.8-magnitude earthquake]] with an epicenter further west in Nepal.

==See also==
* [[1897 Assam earthquake]]
* [[2009 Bhutan earthquake]]
* [[April 2015 Nepal earthquake]]
* [[List of earthquakes in 1950]]
* [[List of earthquakes in India]]

==References==
{{reflist|refs=
<ref name=ISC-GEM>{{citation|title=ISC-GEM Global Instrumental Earthquake Catalogue (1900–2009)|url=http://www.isc.ac.uk/iscgem/index.php|author=ISC|year=2015|publisher=[[International Seismological Centre]]|series=Version 2.0}}</ref> 
<ref name=PAGER-CAT>{{citation|title=PAGER-CAT Earthquake Catalog|url=https://earthquake.usgs.gov/static/lfs/data/pager/catalogs/|author=USGS|date=September 4, 2009|publisher=[[United States Geological Survey]]|series=Version 2008_06.1}}</ref>
<ref name=USGS>{{cite web|title=M8.6 - eastern Xizang-India border region|url=https://earthquake.usgs.gov/earthquakes/eventpage/iscgem895681#general_region|author=USGS|publisher=[[United States Geological Survey]]}}</ref>
}}

==External links==
* [https://plus.google.com/photos/117129633280973941690/albums/5043490088590857393/5043490208849941890?banner=pwa&pid=5043490208849941890&oid=117129633280973941690 At Khowang] – A photo by Dhaniram Bora
* {{EQ-isc-link|895681}}

{{Earthquakes in China}}
{{Earthquakes in India}}
{{Earthquakes in Myanmar}}
{{Himalayan quakes}}

{{DEFAULTSORT:Assam}}

{{#seo:
|keywords=1950 in India, 1950 in Tibet, 1950 earthquakes, 1950s in Assam, August 1950 events, Disasters in Assam, Earthquakes in Myanmar
|description=
}}

[[Category:1950 in India]]
[[Category:1950 in Tibet]]
[[Category:1950 earthquakes]]
[[Category:1950s in Assam]]
[[Category:August 1950 events]]
[[Category:Disasters in Assam]]
[[Category:Earthquakes in India|1950 Assam]]
[[Category:Earthquakes in Tibet|1950 Assam]]
[[Category:Earthquakes in Assam|1950 Assam]]
[[Category:Earthquakes in Myanmar]]