Felorox at 11:07, 2 August 2025

2025-08-02T11:07:35Z

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{{Short description|Geological fault in the Himalayas}}

[[File:Himalayas landsat 7.png|thumb|300x300px|Figure 1. Satellite view of the Himalayas. The Main Frontal Thrust run parallel to the glaciated peaks, north of the [[Indo-Gangetic Plain]].]]
{{Infobox fault|name=Main Frontal Thrust|other_name=Himalayan Frontal Thrust|country=[[Nepal]], [[India]], [[Pakistan]], [[Bhutan]]|length=2,400 km|range=[[Himalayas]]|type=Thrust|map_image=Himalayan Tectonic Summary.png|displacement=15-21 mm/yr|status=Active|image_caption=Map of the Himalaya region with earthquakes M6+ from 1900-2014. the MFT is at the continuous black line running along}}

The '''Main Frontal Thrust (MFT)''', also known as the '''Himalayan Frontal Thrust (HFT)''', is a geological [[Fault (geology)|fault]] in the [[Himalayas]] that defines the boundary between the [[Himalayan foothills]] and [[Indo-Gangetic Plain]].<ref name="Paul_&_Bhakuni_">{{Cite web|last1=Paul|first1=R.|last2=Bhakuni|first2=S.S.|title=Structural analysis of main boundary thrust and Himalayan frontal thrust around Dehra Dun, NW Himalaya: Implications of neotectonics|url=http://reports.ias.ac.in/report/18600/structural-analysis-of-main-boundary-thrust-and-himalayan-frontal-thrust-around-dehra-dun-nw-himalaya-implications-of-neotectonics|access-date=21 October 2020|website=Summer Research Fellowship Programme of India's Science Academies|archive-date=21 October 2020|archive-url=https://web.archive.org/web/20201021095249/http://reports.ias.ac.in/report/18600/structural-analysis-of-main-boundary-thrust-and-himalayan-frontal-thrust-around-dehra-dun-nw-himalaya-implications-of-neotectonics|url-status=dead}}</ref> The fault is well expressed on the surface thus could be seen via satellite imagery. It is the youngest and southernmost [[Thrust fault|thrust]] structure in the Himalaya [[Thrust tectonics|deformation front]]. It is a splay branch of the [[Main Himalayan Thrust]] (MHT) as the root [[décollement]].

==Background==
It runs parallel to other major splays of the MHT, the Main Boundary Thrust (MBT) and Main Central Thrust (MCT). The [[Sunda megathrust|Sunda Megathrust]], which extends from the Banda Islands to [[Myanmar]], is joined with the MFT.<ref name=":0">{{Cite journal |last1=Burgess |first1=W.P. |last2=Yin |first2=A. |last3=Dubey |first3=C.S. |last4=Shen |first4=Z–K. |last5=Kelty |first5=T.K. |date=2012 |title=Holocene shortening across the Main Frontal Thrust zone in the eastern Himalaya |url=https://www.researchgate.net/publication/256695341 |journal=Earth and Planetary Science Letters |volume=357–358 |pages=152–167 |doi=10.1016/j.epsl.2012.09.040|bibcode=2012E&PSL.357..152P }}</ref> The fault [[Strike and dip|strikes]] in a northwest-southeast direction and [[Strike and dip|dips]] at an angle of 20° to 30° in the north.<ref name="Wesnousky_etal_1999">{{Cite journal |last1=Wesnousky |first1=S.G. |last2=Kumar |first2=S. |last3=Mohindra |first3=R. |last4=Thakur |first4=V.C. |date=1999 |title=Uplift and convergence along the Himalayan Frontal Thrust of India |url=https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/1999TC900026 |journal=Tectonics |volume=18 |issue=6 |pages=967–976 |doi=10.1029/1999TC900026|bibcode=1999Tecto..18..967W |s2cid=128412302 |url-access=subscription }}</ref>

The Main Boundary Thrust is another major thrust fault in the [[Himalayan orogenic zone|Himalaya orogenic]] wedge that was active in the [[Cenozoic]].<ref name="Mugnier_etal_1994">{{Cite journal |last1=Mugnier |first1=J–L. |last2=Huyghe |first2=P. |last3=Chalaron |first3=E. |last4=Mascle |first4=G. |date=1994 |title=Recent movements along the Main Boundary Thrust of the Himalayas: Normal faulting in an over-critical thrust wedge? |url=https://www.researchgate.net/publication/215614466 |journal=Tectonophysics |volume=238 |issue=1–4 |pages=199–215 |doi=10.1016/0040-1951(94)90056-6|bibcode=1994Tectp.238..199M }}</ref> It runs parallel to the MFT with a spacing distance of about 20 km.

== Shortening rate ==
Shortening rate varies across the MFT; these figures provide the speed in various locations.<ref name=":0" />
{| class="wikitable"
|+
!Region
!Rate (mm/yr)
!Notes
|-
|[[Pakistan]]
|14 ± 4
|Minor components within the Himalayas also account for shortening.
|-
|[[North India|Northwestern India]]
|12 ± 2
|
|-
|[[Nepal]]
|21 ± 1.5
|
|-
|[[Bhutan]]
|17.5 ± 2.5
|
|}

== Seismic activity ==
The MFT accommodates almost the entire rate of subduction of the [[Indian Plate]]; numerous large earthquakes have occurred along this fault, and is expected to produce more in the future.<ref name=Bilham>{{Cite book|last1=Bilham |first1=R. |editor1-last=Treloar |editor1-first=P.J. |editor2-last=Searle |editor2-first=M.P. |title=Himalayan Tectonics: A Modern Synthesis |chapter=Himalayan earthquakes: a review of historical seismicity and early 21st century slip potential |series=Geological Society, London, Special Publications |year=2019 |volume=483 |pages=423–482 |doi=10.1144/SP483.16|isbn = 9781786204059|s2cid=133821585 }}</ref> Many earthquakes associated with the MFT has resulted in visible [[Surface rupture|ground ruptures]], as seen in the [[1934 Nepal–India earthquake|Bihar earthquake of 1934]] and [[1505 Lo Mustang earthquake|1505 magnitude 8.2–8.8 earthquake]].

== 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 Asia]]
[[Category:Geology of Nepal]]
[[Category:Geology of Pakistan]]
[[Category:Geology of India]]
[[Category:Geology of China]]
[[Category:Geology of Bhutan]]

Main Frontal Thrust - Revision history

Felorox at 11:07, 2 August 2025