{{Short description|Geological feature}} {{Infobox fault |name=Main Himalayan Thrust |location=Himalayas |type=Thrust fault |length=>2,000km |earthquakes= |status=Active |strike=northwest-southeast }} thumb|500x500px|A geological map of the Himalaya region. The Main Himalayan Thrust underlies the rock units. thumb|Diagram showing a décollement 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 largest active continental megathrust<ref name="Sieh07">{{cite journal |last1=Sieh |first1=Kerry |title=The Sunda megathrust - Past, present and future |journal=Journal of Earthquake and Tsunami |date=2007 |volume=1 |page=1-19 |url=http://tecto.caltech.edu/sumatra/downloads/papers/Snu.pdf |publisher=California Institute of Technology |doi=10.1142/S179343110700002X |issn=1793-4311}}</ref> fault in the world.<ref name="Liu_etal_2020">{{Cite journal |last1=Liu |first1=Y. |last2=Hubbard |first2=J. |last3=Almeida |first3=R.V. |last4=Foster |first4=A. |last5=Liberty |first5=L. |last6=Lee |first6=Y.S. |last7=Sapkota |first7=S.N. |date=2020 |title=Constraints on the Shallow Deformation Around the Main Frontal Thrust in Central Nepal from Refraction Velocities |url=https://scholarworks.boisestate.edu/cgi/viewcontent.cgi?article=1511&context=geo_facpubs |journal=Tectonophysics |volume=777 |article-number=228366 |doi=10.1016/j.tecto.2020.228366 |via=Boise State University|doi-access=free |bibcode=2020Tectp.77728366L |hdl=10356/143621 |hdl-access=free }}</ref>
== Overview == The MHT accommodates crustal shortening of India and Eurasia as a result of the ongoing collision between the Indian and Eurasian plates.<ref name="Hubbard_etal_2016">{{Cite journal |last1=Hubbard |first1=J. |last2=Almeida |first2=R. |last3=Foster |first3=A. |last4=Sapkota |first4=S.N. |last5=Bürgi |first5=P. |last6=Tapponnier |first6=P. |date=2016 |title=Structural segmentation controlled the 2015 Mw 7.8 Gorkha earthquake rupture in Nepal |url=https://www.researchgate.net/publication/305269615 |journal=Geology |volume=44 |issue=8 |pages=639–642 |doi=10.1130/G38077.1|doi-access=free |bibcode=2016Geo....44..639H |hdl=10220/50430 |hdl-access=free }}</ref> The MHT absorbs around 20mm/yr of slip, nearly half of the total convergence rate. This slip can be released from small-scale earthquakes and some plastic deformation, but the MHT still accumulates a deficit of moment of {{Nowrap|{{val|6.6e19}} Nm/yr}}. The MHT also remains locked with the overlying Eurasian plate from its surface expression to the front of the higher Himalayas, nearly 100 kilometres away. This locking mechanism combined with the rapid accumulation of deficit of moment are concerning, as some professionals estimate that earthquakes up to the size of 8.9 on the Richter scale could be in order for regions such as western Nepal. Earthquakes of this magnitude are estimated to have a return period of over 1000 years in this region.<ref>Ader, Thomas, et al. "Convergence Rate across the Nepal Himalaya and Interseismic Coupling on the Main Himalayan Thrust: Implications for Seismic Hazard." ''Journal of Geophysical Research: Solid Earth'', vol. 117, no. B4, 2012, {{doi|10.1029/2011jb009071}}.</ref> Deformation of the crust is also accommodated along splay structures including the Main Frontal Thrust (MFT), Main Boundary Thrust (MBT), Main Central Thrust (MCT), and possibly the South Tibetan Detachment. The MHT is the root detachment of these splays. Currently, the MFT and MHT accounts for almost the entire rate of convergence (15–21 mm/yr).<ref name="Roux-Mallouf_etal_2015">{{Cite journal |last1=Le Roux-Mallouf |first1=R. |last2=Godard |first2=V. |last3=Cattin |first3=R. |last4=Ferry |first4=M. |last5=Gyeltshen |first5=J. |last6=Ritz |first6=J.–F. |last7=Drupka |first7=D. |last8=Guillou |first8=V. |last9=Arnold |first9=M. |last10=Aumaitre |first10=G. |last11=Bourlès |first11=D.L. |last12=Keddadouche|first12=K.|date=2015 |title=Evidence for a wide and gently dipping Main Himalayan Thrust in western Bhutan |url=http://www.gm.univ-montp2.fr/spip/IMG/pdf/cattingrl15.pdf |journal=Geophysical Research Letters |volume=42 |issue=9 |pages=3257–3265 |doi=10.1002/2015GL063767|bibcode=2015GeoRL..42.3257L |s2cid=30608419 }}</ref><ref name="Hubbard_EOS">{{Cite web |last=Hubbard |first=J. |title=Geometry and Kinematics of the Main Frontal Thrust, Himalaya |url=https://earthobservatory.sg/project/geometry-and-kinematics-main-frontal-thrust-himalaya |access-date=27 October 2020 |website=Earth Observatory of Singapore}}</ref> This fault defines where the Indian subcontinent is underthrust beneath the Himalayan orogenic wedge.
==Seismic hazard== The MHT is a known hazard and potential source for large earthquakes of magnitude 8.0 or greater. The MHT is also associated with other large 20th-century earthquakes such as the 1934 Nepal–India earthquake and the 1950 Assam–Tibet earthquake. Within the last thousand years, multiple earthquakes have occurred with magnitudes of at least {{M|w}}8.0 as deduced by paleoseismology. Michel et al. (2021) suggested the maximum magnitude possible on the MHT to be {{M|w}}8.7 with a recurrence interval of 200 years.<ref name="Michel1">{{cite journal |last1=Michel |first1=Sylvain |last2=Jolivet |first2=Romain |last3=Rollins |first3=Chris |last4=Jara |first4=Jorge |last5=Zilio |first5=Luca Dal |title=Seismogenic Potential of the Main Himalayan Thrust Constrained by Coupling Segmentation and Earthquake Scaling |journal=Geophysical Research Letters |date=2021 |volume=48 |issue=13 |doi=10.1029/2021GL093106|pmc=9285541 }}</ref>
In April 2015, a section of the MHT produced a blind rupture earthquake, killing nearly 9,000 people.<ref name=":1">{{Cite web|last=|first=|date=|title=M 7.8 - 36km E of Khudi, Nepal|url=https://earthquake.usgs.gov/earthquakes/eventpage/us20002926/executive|archive-url=https://web.archive.org/web/20200813083448/https://earthquake.usgs.gov/earthquakes/eventpage/us20002926/executive|archive-date=2020-08-13|website=US Geological Survey}}</ref><ref name="Duputel_etal_2016">{{Cite journal |last1=Duputel |first1=Z. |last2=Vergne |first2=J. |last3=Rivera |first3=L. |last4=Wittlinger |first4=G. |last5=Farra |first5=V. |last6=Hetényi |first6=G. |date=2016 |title=The 2015 Gorkha earthquake: A large event illuminating the Main Himalayan Thrust fault |url=https://core.ac.uk/download/pdf/77175162.pdf |journal=Geophysical Research Letters |volume=43 |issue=6 |pages=2517–2525 |doi=10.1002/2016GL068083|bibcode=2016GeoRL..43.2517D |s2cid=53463752 }}</ref> Researchers who published their findings in ''Nature Geoscience'' revealed that the {{M|w}}7.8 earthquake failed to rupture towards the surface, thus still leaving the possibility of future large earthquakes. Since the rupture ceased {{cvt|11|km}} beneath the Kathmandu region, a shallow section of the MHT south of the region remains unruptured and could produce an earthquake of comparable size. The research lead, J. R. Elliott, says such an earthquake could be more devastating because of its shallowness.<ref>{{cite news |last1=Koirala |first1=Keshav P. |title=Nepal earthquake "damaged Main Himalayan Thrust fault" |url=https://thehimalayantimes.com/science-and-tech/nepal-earthquake-has-ruptured-main-himalayan-thrust-fault-study |access-date=15 May 2024 |work=The Himalayan |date=12 January 2016}}</ref>
== Associated seismicity == The Main Himalayan Thrust and its splay branches has been the source of numerous earthquakes, including some that are indirectly related. {| class="wikitable" |+ !Date !Country !Magnitude !Depth (km) !MMI !Deaths !Comments !Source <!-- |- | | | | | | | | --> |- |1255-06-07 |Nepal |8.0+ |<nowiki>-</nowiki> | | |Rupture length uncertain but possibly in the hundreds of kilometers. Killed one-third of Nepal(Kathmandu Valley)'s population. |<ref>{{Cite journal |last=National Geophysical Data Center / World Data Service (NGDC/WDS): NCEI/WDS Global Significant Earthquake Database. NOAA National Centers for Environmental Information |title=Comments for the 1255 Earthquake |url=https://www.ngdc.noaa.gov/nndc/struts/results?eq_0=9947&t=101650&s=13&d=22,26,13,12&nd=display |website=NOAA |year=1972 |publisher=National Geophysical Data Center, NOAA |doi=10.7289/V5TD9V7K |access-date=2020-10-17 |archive-date=2017-12-16 |archive-url=https://web.archive.org/web/20171216112019/https://www.ngdc.noaa.gov/nndc/struts/results?eq_0=9947&t=101650&s=13&d=22,26,13,12&nd=display }}</ref><ref name="Pierce_&_Wesnousky_2016">{{Cite journal |last1=Pierce |first1=I. |last2=Wesnousky |first2=S.G. |date=2016 |title=On a flawed conclusion that the 1255 A.D. earthquake ruptured 800 km of the Himalayan Frontal Thrust east of Kathmandu |url=https://www.researchgate.net/publication/307553126 |journal=Geophysical Research Letters |volume=43 |issue=17 |pages=9026–9029 |doi=10.1002/2016GL070426|doi-access=free |bibcode=2016GeoRL..43.9026P }}</ref> |- |1344-09-14 |Nepal | | - | | | |<ref name="Bollinger_etal_2016">{{Cite journal |last1=Bollinger |first1=L. |last2=Tapponnier |first2=P. |author-link2=Paul Tapponnier |last3=Sapkota |first3=S.N. |last4=Klinger |first4=Y. |title=Slip deficit in central Nepal: omen for a repeat of the 1344 AD earthquake? |journal=Earth Planets Space |year=2016 |volume=68 |issue=12 |doi=10.1186/s40623-016-0389-1|s2cid=32078899 |doi-access=free |bibcode=2016EP&S...68...12B |hdl=10220/39981 |hdl-access=free }}</ref> |- |1408 |Nepal | | - | | | |<ref name="Bollinger_etal_2016"/> |- |1505-06-06 |Nepal, India and China |8.2–8.8<ref name="MKJHA">{{cite book |last=Jha |first=Madan Kumar |date=2010 |title=Natural and Anthropogenic Disasters: Vulnerability, Preparedness and Mitigation |url=https://archive.org/details/naturalanthropog00jham_873|url-access=limited |location=New Delhi |publisher=Springer |pages=[https://archive.org/details/naturalanthropog00jham_873/page/n37 25]–26 |isbn=978-90-481-2497-8}}</ref><ref name="Bilham&Ambraseys_2005">{{cite journal | url=http://www.iisc.ernet.in/~currsci/may252005/1658.pdf | title=Apparent Himalayan slip deficit from the summation of seismic moments for Himalayan earthquakes, 1500–2000 | author=Bilham R. | author2=Ambraseys N.N. | author-link2=Nicholas Ambraseys | journal=Current Science | year=2005 | volume=88 | issue=10 | pages=1658–1663 | jstor=24110492 | access-date=2015-08-21 | archive-date=2016-03-04 | archive-url=https://web.archive.org/web/20160304112434/http://www.iisc.ernet.in/~currsci/may252005/1658.pdf }}</ref> |<nowiki>-</nowiki> | | |Killed 30% of the Nepalese population. |<ref name="Rajendran_etal_2013">{{Cite journal |last1=Rajendran |first1=C.P. |last2=Rajendran |first2=K. |last3=Sanwal |first3=J. |last4=Sandiford |first4=M. |date=2013 |title=Archeological and Historical Database on the Medieval Earthquakes of the Central Himalaya: Ambiguities and Inferences |url=http://www.seismosoc.org/Publications/srl/SRL_84/srl_84-6_hs_II/srl_84-6_hs_II.pdf |journal= Seismological Research Letters|volume=84 |issue=6 |pages=1098–1108 |doi=10.1785/0220130077|bibcode=2013SeiRL..84.1098R }}</ref> |- |1680 |Nepal |<7.5 | - | | | |<ref name="Bollinger_etal_2016"/> |- |1714-05-4 |Bhutan |7.6–8.6 | - | IX | "Many" | Ruptured the whole Bhutan section of the Main Frontal Thrust. | <ref name="Zhao_etal_2021">{{Cite journal |last1=Zhao |first1=Y. |last2=Grujic |first2=D. |last3=Baruah |first3=S. |last4=Drukpa |first4=D. |last5=Elkadi |first5=J. |last6=Hetényi |first6=G. |last7=King |first7=G.E. |last8=Mildon |first8=Z.K. |last9=Nepal |first9=N. |last10=Welte |first10=C. |date=2021 |title=Paleoseismological Findings at a New Trench Indicate the 1714 M8.1 Earthquake Ruptured the Main Frontal Thrust Over all the Bhutan Himalaya |journal=Frontiers in Earth Science |volume=9 |doi=10.3389/feart.2021.689457|doi-access=free |hdl=10026.1/18289 |hdl-access=free }}</ref> |- |1803-09-01 |India |7.8–7.9 | - | IX | 300 | Damage as far as New Delhi. | |- |1833-08-26 |Nepal |7.5–7.9 | - | IX | 500 |Severely damaged Kathmandu and was felt as far as Calcutta. |<ref name="Chaulagain_etal_2018">{{Cite book |last1=Chaulagain |first1=H. |last2=Gautam |first2=D. |last3=Rodrigues |first3=H. |date=2018 |title=Impacts and Insights of the Gorkha Earthquake |publisher=Elsevier |isbn=978-0-12-812809-1 |editor-last=Gautam |editor-first=D. |pages=1–17 |chapter=Chapter 1 - Revisiting Major Historical Earthquakes in Nepal: Overview of 1833, 1934, 1980, 1988, 2011, and 2015 Seismic Events |editor-last2=Rodrigues |editor-first2=H.F.P. |chapter-url=https://books.google.com/books?id=HDtHDgAAQBAJ&q=Revisiting+Major+Historical+Earthquakes+in+Nepal}}</ref> |- |1905-04-04 |India |7.9 | - | X |20,000+ | |<ref name="Pant_etal_">{{Cite book |last1=Pant |first1=C.C. |url=https://ansab.org.np/storage/product/lessons-from-nepal-earthquake-for-the-indian-himalayas-and-the-gangetic-plains-min-1579162485.pdf |title=Lessons From Nepal's Earthquake For The Indian Himalayas And The Gangetic Plains |last2=Pathak |first2=V. |last3=Joshi |first3=S. |publisher=Central Himalayan Environment Association |year=2016 |editor-last=Singh |editor-first=S.P. |page=31 |chapter=Extant Seismicity and Regional Tectonic Interpretation: An illustration from Kumaun Himalaya, Uttarakhand, India |editor-last2=Khanal |editor-first2=S.C. |editor-last3=Joshi |editor-first3=M.}}</ref> |- |1934-01-05 |Nepal and India |8.1 |15.0 |XI |12,000 |Ruptured to the surface via the Main Frontal Thrust. |<ref>{{Cite web|last=|first=|date=|title=M 8.0 - Nepal-India border region|url=https://earthquake.usgs.gov/earthquakes/eventpage/iscgem904745/executive|archive-url=https://web.archive.org/web/20201018024206/https://earthquake.usgs.gov/earthquakes/eventpage/iscgem904745/executive|archive-date=2020-10-18|website=US Geological Survey}}</ref> |- |1947-07-29 |China |7.3 |20.0 |V | | | |- |1950-08-15 |India, China and Myanmar |8.6 |15.0 |XI |4,800 |Ranks among the largest Strike-slip earthquake ever instrumentally recorded. |<ref>{{Cite web|last=|first=|date=|title=M 8.6 - 1950 Assam-Tibet Earthquake|url=https://earthquake.usgs.gov/earthquakes/eventpage/official19500815140934_30/executive|archive-url=https://web.archive.org/web/20201019004145/https://earthquake.usgs.gov/earthquakes/eventpage/official19500815140934_30/executive|archive-date=2020-10-19|website=US Geological Survey}}</ref> |- |1966-06-27 |Nepal and India |6.1 |37.0 | |80 | |<ref>{{Cite journal|author=P. N. Agrawal|journal=Bulletin of the Seismological Society of America|date=1969|title=Structural response results during the June 27, 1966 earthquake in Nepal-India border region|url=https://pubs.geoscienceworld.org/ssa/bssa/article-abstract/59/2/771/116722/Structural-response-results-during-the-June-27?redirectedFrom=fulltext|volume=59|issue=2|pages=771–775|doi=10.1785/BSSA0590020771 |bibcode=1969BuSSA..59..771A |url-access=subscription}}</ref> |- |1980-07-29 |Nepal and India |6.5 |17.5 |VIII |200 | |<ref name="USGS">{{cite web |title=M 6.5 - 40 km NNE of Dipayal, Nepal |url=https://earthquake.usgs.gov/earthquakes/eventpage/usp0001959/executive |website=earthquake.usgs.gov |publisher=U.S. Geological Survey |access-date=10 January 2022}}</ref> |- |1988-08-21 |Nepal |6.9 |57.4 |VIII |700-1400 | | |- |1991-10-20 |India |6.8 |10.3 |IX |2000 |Main Central Thrust. | |- |1999-03-29 |India |6.8 |21.0 |VII |103 | | |- |2005-10-08 |Pakistan |7.6 |26.0 |XI |87,400 | |<ref name="Ali et. al">{{cite journal |author1=Zahid Ali |author2=Muhammad Qaisar |author3=Tariq Mahmood |author4=Muhammad Ali Shah |author5=Talat Iqbal |author6=Leonello Serva |author7=Alessandro M. Michetti |author8=Paul W. Burton |title=The Muzaffarabad, Pakistan, earthquake of 8 October 2005: surface faulting, environmental effects and macroseismic intensity |journal=Special Publications |date=2009 |volume=316 |issue=1 |pages=155–172 |doi=10.1144/SP316.9 |url=https://sp.lyellcollection.org/content/316/1/155?ck=nck |publisher=The Geological Society of London|bibcode=2009GSLSP.316..155A |s2cid=128469925 |url-access=subscription }}</ref> |- |2009-09-21 |Bhutan |6.1 |14.0 |VI |11 | |<ref>{{Cite web|last=|first=|date=|title=M 6.1 - Bhutan|url=https://earthquake.usgs.gov/earthquakes/eventpage/iscgem13788745/executive|website=US Geological Survey}}</ref> |- |2011-09-18 |India |6.9 |50.0 |VII |111 |Intraplate strike-slip. | |- |2013-05-01 |Pakistan and India |5.7 |15.0 |VII |1 |Additional 59 injured. |<ref name="Ahmad">{{cite news |author1=Mukhtar Ahmad |title=Moderate earthquake kills 1, injures 59 in eastern Kashmir |url=https://edition.cnn.com/2013/05/01/world/asia/india-earthquake/index.html |access-date=10 January 2022 |work=CNN |date=1 May 2013}}</ref> |- |2015-04-25 |Nepal |7.8 |8.2 |VIII |8,964 | |<ref name=":1" /> |- |2015-05-12 |Nepal |7.3 |18.5 |VIII |218 |Aftershock of the April 2015 earthquake. |<ref name="Hubbard_etal_2016"/> |- |2015-07-24 |Pakistan |5.1 |17.0 |V |3 | |<ref>{{Cite web|last=|first=|date=|title=M 5.1 - 19km WSW of Murree, Pakistan|url=https://earthquake.usgs.gov/earthquakes/eventpage/us20002zz3/executive|archive-url=https://web.archive.org/web/20201028212245/https://earthquake.usgs.gov/earthquakes/eventpage/us20002zz3/executive|archive-date=2020-10-28|website=US Geological Survey}}</ref> |- |2019-09-24 |Pakistan |6.0 |10.0 |VII |40 | |<ref name="Sreejith">{{cite journal |first1=K.M. |last1=Sreejith |first2=M.C.M. |last2=Jasir |first3=R. |last3=Agrawal |first4=A.S. |last4=Rajawat |title=The 2019 September 24, Mw = 6, Mirpur earthquake, NW Himalaya: Geodetic evidence for shallow, near-horizontal décollement rupture of the Main Himalayan Thrust |journal=Tectonophysics |year=2021 |volume=816 |issue=229013 |doi=10.1016/j.tecto.2021.229013 |url=https://www.sciencedirect.com/science/article/abs/pii/S004019512100295X |publisher=Elsevier|url-access=subscription }}</ref> |}
==See also== *Geology of the Himalaya
== References == <references />
Category:Tectonics Category:Himalayas Category:Active faults Category:Structural geology Category:Seismic faults Category:Seismic faults of Asia Category:Thrust faults Category:Seismic faults of Pakistan Category:Geology of the Himalaya Category:Subduction zones Category:Geology of Nepal Category:Geology of Asia Category:Geology of India Category:Geology of Pakistan Category:Geology of China Category:Geology of Bhutan