2021 Assam earthquake
{{Short description|Earthquake in India}}
{{Infobox earthquake
| isc-event = 620343980
| magnitude = 6.0 {{M|w|link=y}}
| local-time = 07:51 (IST)
| location = {{Coord|26.781|N|92.457|E}}
| anss-url = us7000dy3b
| name = 2021 Assam earthquake
| timestamp = 2021-04-28 02:21:26
| map2 = {{Location map|India Assam#India
|lat=26.77
|long=92.43
|mark=Bullseye1.png
|marksize=50
|position=top
|width=260
|caption=
|relief=yes
|label=}}
| alt =
| pga =
| depth = {{Cvt|34|km|mi}}
| intensity = {{MMI|6}}
| image =
| local-date = 28 April 2021
| aftershocks = Several. The strongest so far is a {{M|w}} 4.7{{cite web |title=Explained: In Assam earthquake, reminder of seismic hazard along HFT faultline|date=28 April 2021 |url=https://indianexpress.com/article/explained/explained-in-assam-earthquake-reminder-of-seismic-hazard-along-hft-faultline-7292770/ |publisher=The Indian Express |access-date=28 April 2021}}
| fault = Kopili Fault
| casualties = 2 dead, 12 injured
| countries affected = Bangladesh, China, Myanmar, Bhutan, and India
}}
The 2021 Assam earthquake struck 11 km (7 miles) away from Dhekiajuli, Assam, India at 07:51 (IST) on April 28, 2021 with a moment magnitude of 6.0 at {{cvt|34.0|km}} depth.{{cite web |title=M 6.0 - 9 km NNW of Dhekiajuli, India |url=https://earthquake.usgs.gov/earthquakes/eventpage/us7000dy3b/executive |website=earthquake.usgs.gov |publisher=United States Geological Survey |access-date=14 May 2021}}{{Cite web|date=2021-04-28|title=Northeast India hit by magnitude 6.4 earthquake|url=https://www.independent.co.uk/asia/india/india-earthquake-today-assam-latest-b1838656.html |archive-url=https://web.archive.org/web/20210428175455/https://www.independent.co.uk/asia/india/india-earthquake-today-assam-latest-b1838656.html |archive-date=2021-04-28 |url-access=limited |url-status=live|access-date=2021-04-28|website=The Independent|language=en}} The quake struck with an epicenter 140 km (86 miles) north of the main city of Guwahati. It resulted in two fatalities and at least 12 injuries.
Tectonic setting
The tectonics of the Assam region is dominated by convergence of the India, Burma and Eurasian plates. Major fault structures like the Main Frontal Thrust, Main Boundary Thrust and Main Central Thrust, all splay branches of the Main Himalayan Thrust, accommodate the shortening rate as India is pushing into Asia. The large 8.6 {{M|w}} Assam–Tibet earthquake in 1950 was a megathrust earthquake that resulted from a rupture along the Main Himalayan Thrust and Main Frontal Thrust.
Earthquake
File:2021-04-28 Dhekiajuli, India M6 earthquake shakemap (USGS).jpg
The earthquake occurred as a result of oblique-slip faulting at a shallow depth just at the foothills of the Himalayas.{{cite web |title=Assam Earthquake: 6.4 magnitude quake, 7 aftershocks jolt Northeast, tremors felt in Bengal |url=https://www.indiatoday.in/india/story/earthquake-in-northeast-tremors-felt-in-assam-north-bengal-arunachal-pradesh-1795696-2021-04-28 |publisher=India Today |access-date=28 April 2021}}{{Cite web|title=Official Website of National Center of Seismology|url=https://seismo.gov.in/MIS/riseq/interactive/index/ZVNoMWsrTTlhMEZUUXN1UEgxbUcxUT09/Reviewed|access-date=2021-05-03|website=seismo.gov.in}} Analysis by India's National Centre for Seismology revealed that the earthquake involved slip along the Kopili Fault, near the Main Frontal Thrust.{{cite news |last1=Chakravartty |first1=Anupam |title=Assam earthquake: Known to cause deadly tremors, Kopili fault eludes experts |url=https://www.eastmojo.com/assam/2021/04/29/assam-earthquake-known-to-cause-deadly-tremors-kopili-fault-eludes-experts/ |access-date=15 May 2021 |agency=EastMojo |date=29 April 2021}} This is a northeast striking fault structure that runs from east of the Shillong Plateau, through the Assam Valley and into Bhutan for a total estimated length of 300 km, and a width of 30 km.{{cite journal |last1=Kayal, J., Arefiev, S., Baruah, S., Tatevossian, R., Gogoi, N., Sanoujam, M., Gautam, J.L., Hazarika, D., & Borah, D. |title=The 2009 Bhutan and Assam felt earthquakes (Mw 6.3 and 5.1) at the Kopili fault in the northeast Himalaya region |journal=Geomatics, Natural Hazards and Risk |date=2010 |volume=1 |issue=3 |pages=273–281 |doi=10.1080/19475705.2010.486561|bibcode=2010GNHR....1..273K |doi-access=free }} Its predominant slip sense is right-lateral strike-slip.{{cite journal |last1=Kharita |first1=Akash |title=Strong earthquake jolts Assam |url=https://temblor.net/earthquake-insights/strong-earthquake-jolts-assam-12692/ |journal=Temblor |year=2021 |access-date=15 May 2021 |doi=10.32858/temblor.171|s2cid=235873655 |url-access=subscription }}
The same fault is believed to have caused an {{M|wb}} 6.1 earthquake in Bhutan in 2009, killing 11 and injuring dozens.{{cite web |title=M 6.1 - Bhutan |url=https://earthquake.usgs.gov/earthquakes/eventpage/usp000h1r4/executive |website=earthquake.usgs.gov |publisher=USGS |access-date=15 May 2021}} Two other {{M|w}} 7.0+ earthquakes rocked the Assam Valley in 1869 and 1943, is believed to have been on this fault, as well as the deadly 2016 Imphal earthquake on its southern termination.{{cite journal |last1=Dey |first1=C. |last2=Baruah |first2=S. |last3=Abdelwahed |first3=M. F. |last4=Saikia |first4=S. |last5=Molia |first5=N. |last6=Borthakur |first6=P. |last7=Chetia |first7=T. |last8=Bharali |first8=B. |last9=Dutta |first9=N. |last10=Phukan |first10=M. K. |last11=Paul |first11=A. |last12=Saitlunga |last13=Hazarika |first13=D. |last14=Kayal |first14=J. R. |title=The 28 April 2021 Kopili Fault Earthquake (Mw 6.1) in Assam Valley of North East India: Seismotectonic Appraisal |journal=Pure and Applied Geophysics |date=2022 |volume=179 |issue=6–7 |pages=2167–2182 |doi=10.1007/s00024-022-03072-2|bibcode=2022PApGe.179.2167D |s2cid=250025527 }}
Impact
The earthquake caused moderate but widespread damage to nearby buildings, although no collapses were reported.{{Cite web|date=2021-04-28|title=Quake of magnitude 6 strikes India's Assam, damages some buildings|url=https://www.reuters.com/world/india/magnitude-62-earthquake-strikes-assam-india-emsc-2021-04-28/|access-date=2021-04-28|website=Reuters}} It was assigned a maximum Modified Mercalli intensity of VI (Strong). Among the buildings affected was a multi-story structure in Nagaon which tilted to its side and leaned against an adjacent building. Cracks also appeared in the walls of homes and commercial buildings. A few vehicles were damaged when bricks fell on them.{{cite news |title=From damage caused to relief operations, Assam earthquake explained in 10 points |url=https://www.indiatoday.in/coronavirus-outbreak/story/damage-caused-relief-operations-assam-earthquake-1796077-2021-04-29 |access-date=15 May 2021 |agency=India Today |date=29 April 2021 |location=New Delhi}} Landslides and liquefaction of the ground were reported in Assam.{{cite news |title=Cracked roads, tilted buildings: Assam earthquake captured in scary photos, videos |url=https://www.indiatoday.in/india/story/massive-earthquake-assam-buildings-damaged-walls-cracked-photos-videos-1795765-2021-04-28 |access-date=15 May 2021 |agency=India Today |date=28 April 2021 |location=New Delhi}} Damage to buildings were also reported in nearby Bhutan, and two individuals were injured.{{cite news |title=Earthquake causes structural damage |url=https://kuenselonline.com/earthquake-causes-structural-damage/ |access-date=15 May 2021 |agency=kuenselonline.com}} Two people in the Kamrup Metro and Nagaon districts died of heart attacks caused by the earthquake while 12 others suffered injuries.{{cite news |last1=Saha |first1=Abhishek |title=Assam earthquake: At least 10 injured, houses damaged |url=https://indianexpress.com/article/north-east-india/assam/assam-bengal-earthquake-7291892/ |access-date=15 May 2021 |agency=The Indian Express |date=29 April 2021 |location=Guwahati}}{{cite news |title=Two die of shock after 6.4 magnitude quake in Assam |url=https://www.thehindu.com/news/national/other-states/earthquake-of-magnitude-64-strikes-assam/article34427787.ece |access-date=15 May 2021 |agency=The Hindu |date=28 April 2021}}
See also
{{Portal|India|Earth sciences}}
References
{{reflist}}
{{Earthquakes in 2021}}
{{Earthquakes in India}}
{{Himalayan earthquakes}}
Category:Natural disasters in Bhutan