Strong Earthquake hits Assam, tremors felt across North-East
- Posted By
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.