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Strong Earthquake hits Assam, tremors felt across North-East

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    29th Apr, 2021


Assam tremor has highlighted vulnerability of North East India to large earthquakes

The Kopili fault

  • The tremors have been attributed by the NCS to the Kopili fault zone closer to Himalayan Frontal Thrust.
  • This is a seismically active area falling in the highest Seismic Hazard Zone V.
  • It is associated with collisional tectonics because of the Indian Plate subducting beneath the Eurasian Plate.
  • Subduction is a geological process in which one crustal plate is forced below the edge of another.
  • The Kopili fault zone is a 300 km long and 50 km wide lineament (linear feature) extending from the western part of Manipur up to the tri-junction of Bhutan, Arunachal Pradesh and Assam.
  • The fault itself is a transpressional fracture that generates lower crustal dextral strike-slip earthquakes.

Himalayan Frontal Thrust (HFT)

  • HFT, also known as the Main Frontal Thrust (MFT), is a geological fault along the boundary of the Indian and Eurasian tectonic plates.

What is fault?

  • The United States Geological Survey (USGS), a scientific agency of the US federal government, defines a fault as “a fracture along which the blocks of crust on either side have moved relative to one another parallel to the fracture”.
  • When an earthquake occurs on one of these faults, the rock on one side of the fault slips with respect to the other.
  • The fault surface can be vertical, horizontal, or at some angle to the surface of the earth.