The 2021 Assam earthquake struck 11 km (7 miles) away from Dhekiajuli, Assam, India at 07:51 (IST) on April 28, 2021 with a richter scale magnitude of 6.4. The quake struck at a depth of 34 km (21 miles), 140 km (86 miles) north of the main city of

Guwahati Guwahati (, ; formerly rendered Gauhati, ) is the biggest city of the Indian state of Assam and also the largest metropolis in northeastern India. Dispur, the capital of Assam, is in the circuit city region located within Guwahati and is the ...

. 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 The Main Frontal Thrust (MFT), also known as the Himalayan Frontal Thrust (HFT) is a geological fault in the Himalayas that defines the boundary between the Himalayan foothills and Indo-Gangetic Plain. The fault is well expressed on the surfac ...

, Main Boundary Thrust and

Main Central Thrust The Main Central Thrust is a major geological fault where the Indian Plate has pushed under the Eurasian Plate along the Himalaya. The fault slopes down to the north and is exposed on the surface in a NW-SE direction (strike). It is a thrust fault ...

, all splay branches of the

Main Himalayan Thrust The Main Himalayan Thrust (MHT) is a décollement under the Himalaya Range. This thrust fault follows a NW-SE strike, reminiscent of an arc, and gently dip towards the north, beneath the region. It is the largest active continental megathrust ...

, accommodate the shortening rate as India is pushing into Asia. The large 8.6 Assam–Tibet earthquake in 1950 was a megathrust earthquake that resulted from a rupture along the Main Himalayan Thrust and Main Frontal Thrust.

Earthquake

The earthquake occurred as a result of oblique-slip faulting at a shallow depth just at the foothills of the Himalayas. Analysis by India's

National Centre for Seismology The National Centre for Seismology (NCS) is an office of India's Ministry of Earth Sciences. The office monitors earthquakes and conducts seismological research. Specifically, it provides earthquake surveillance and hazard reports to governmental a ...

revealed that the earthquake involved slip along the Kopili Fault, near the

. 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. Its predominant slip sense is right-lateral strike-slip. The same fault is believed to have caused the an 6.1 earthquake in Bhutan in 2009, killing 11 and injuring dozens. Two other 7.0+ earthquakes rocked the Assam Valley in

1869 Events January–March * January 3 – Abdur Rahman Khan is defeated at Tinah Khan, and exiled from Afghanistan. * January 5 – Scotland's oldest professional football team, Kilmarnock F.C., is founded. * January 20 &ndash ...

and 1943, is believed to have been on this fault, as well as the deadly 2016 Imphal earthquake.

Impact

The earthquake caused moderate but widespread damage to nearby buildings, but no collapses were reported. 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. Landslides and liquefaction of the ground were reported in Assam. Damage to buildings were also reported in nearby Bhutan, and two individuals were injured. Two people in the Kamrup Metro and Nagaon districts died of heart attacks caused by the earthquake while 12 others suffered injuries.

References

{{Himalayan earthquakes 2021 earthquakes Earthquakes in India Earthquakes in Assam Earthquakes in Bhutan 2021 disasters in India 2021 earthquakes in Asia

Tectonic setting

Earthquake

Impact

See also

References