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Assam Earthquake : Himalayan Frontal Thrust

Assam Earthquake:

A powerful earthquake measuring 6.4 on the Richter Scale jolted Assam and other parts of Northeast.

  • According to the National Centre for Seismology (NCS) report, the tremors have been attributed to Kopili Fault zone closer to Himalayan Frontal Thrust (HFT).
  • NCS is the nodal agency of the Government of India for monitoring earthquake activity in the country. It comes under the Ministry of Earth Sciences.

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.
  • Kopili Fault Zone:
    • 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 area is seismically very active falling in the highest Seismic Hazard zone V associated with collisional tectonics where Indian plate subducts beneath the Eurasian Plate.
    • Subduction is a geological process in which one crustal plate is forced below the edge of another.
    • Squeezed between the subduction and collision zones of the Himalayan belt and Sumatran belt, the North East is highly prone to earthquake occurrences.
  • Fault:
    • A fault is 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, 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.