2021 Assam earthquake

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 34.0 km (21.1 mi) depth.[2][3] 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.

2021 Assam earthquake
2021 Assam earthquake is located in Assam
2021 Assam earthquake
2021 Assam earthquake is located in India
2021 Assam earthquake
UTC time2021-04-28 02:21:26
ISC event620343980
USGS-ANSSComCat
Local date28 April 2021
Local time07:51 (IST)
Magnitude6.0 Mw
Depth34 km (21 mi)
Epicenter26.781°N 92.457°E / 26.781; 92.457
FaultKopili Fault
Areas affectedBangladesh, China, Myanmar, Bhutan, and India
Max. intensityVI (Strong)
AftershocksSeveral. The strongest so far is a Mw  4.7[1]
Casualties2 dead, 12 injured

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 Mw  Assam–Tibet earthquake in 1950 was a megathrust earthquake that resulted from a rupture along the Main Himalayan Thrust and Main Frontal Thrust.

Earthquake
Earthquake Intensity Map

The earthquake occurred as a result of oblique-slip faulting at a shallow depth just at the foothills of the Himalayas.[4][5] Analysis by India's National Centre for Seismology revealed that the earthquake involved slip along the Kopili Fault, near the Main Frontal Thrust.[6] 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.[7] Its predominant slip sense is right-lateral strike-slip.[8]

The same fault is believed to have caused an Mwb  6.1 earthquake in Bhutan in 2009, killing 11 and injuring dozens.[9] Two other Mw  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.[7][10]

Impact

The earthquake caused moderate but widespread damage to nearby buildings, although no collapses were reported.[11] It was assigned a maximum Modified Mercalli intensity of VI (Strong).[10] 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.[12] Landslides and liquefaction of the ground were reported in Assam.[13] Damage to buildings were also reported in nearby Bhutan, and two individuals were injured.[14] Two people in the Kamrup Metro and Nagaon districts died of heart attacks caused by the earthquake while 12 others suffered injuries.[15][16]

See also

References
  1. "Explained: In Assam earthquake, reminder of seismic hazard along HFT faultline". The Indian Express. 28 April 2021. Retrieved 28 April 2021.
  2. "M 6.0 - 9 km NNW of Dhekiajuli, India". earthquake.usgs.gov. United States Geological Survey. Retrieved 14 May 2021.
  3. "Northeast India hit by magnitude 6.4 earthquake". The Independent. 2021-04-28. Archived from the original on 2021-04-28. Retrieved 2021-04-28.
  4. "Assam Earthquake: 6.4 magnitude quake, 7 aftershocks jolt Northeast, tremors felt in Bengal". India Today. Retrieved 28 April 2021.
  5. "Official Website of National Center of Seismology". seismo.gov.in. Retrieved 2021-05-03.
  6. Chakravartty, Anupam (29 April 2021). "Assam earthquake: Known to cause deadly tremors, Kopili fault eludes experts". EastMojo. Retrieved 15 May 2021.
  7. Kayal, J., Arefiev, S., Baruah, S., Tatevossian, R., Gogoi, N., Sanoujam, M., Gautam, J.L., Hazarika, D., & Borah, D. (2010). "The 2009 Bhutan and Assam felt earthquakes (Mw 6.3 and 5.1) at the Kopili fault in the northeast Himalaya region". Geomatics, Natural Hazards and Risk. 1 (3): 273–281. doi:10.1080/19475705.2010.486561.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  8. Kharita, Akash (2021). "Strong earthquake jolts Assam". Temblor. doi:10.32858/temblor.171. S2CID 235873655. Retrieved 15 May 2021.
  9. "M 6.1 - Bhutan". earthquake.usgs.gov. USGS. Retrieved 15 May 2021.
  10. Dey, C.; Baruah, S.; Abdelwahed, M. F.; Saikia, S.; Molia, N.; Borthakur, P.; Chetia, T.; Bharali, B.; Dutta, N.; Phukan, M. K.; Paul, A.; Saitlunga; Hazarika, D.; Kayal, J. R. (2022). "The 28 April 2021 Kopili Fault Earthquake (Mw 6.1) in Assam Valley of North East India: Seismotectonic Appraisal". Pure and Applied Geophysics. 179 (6–7): 2167–2182. Bibcode:2022PApGe.179.2167D. doi:10.1007/s00024-022-03072-2. S2CID 250025527.
  11. "Quake of magnitude 6 strikes India's Assam, damages some buildings". Reuters. 2021-04-28. Retrieved 2021-04-28.
  12. "From damage caused to relief operations, Assam earthquake explained in 10 points". New Delhi. India Today. 29 April 2021. Retrieved 15 May 2021.
  13. "Cracked roads, tilted buildings: Assam earthquake captured in scary photos, videos". New Delhi. India Today. 28 April 2021. Retrieved 15 May 2021.
  14. "Earthquake causes structural damage". kuenselonline.com. Retrieved 15 May 2021.
  15. Saha, Abhishek (29 April 2021). "Assam earthquake: At least 10 injured, houses damaged". Guwahati. The Indian Express. Retrieved 15 May 2021.
  16. "Two die of shock after 6.4 magnitude quake in Assam". The Hindu. 28 April 2021. Retrieved 15 May 2021.
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