Tezpur (Assam): The North-Eastern region of India is demarcated as Seismic zone V, which indicates zone with high earthquake vulnerability. The Indian plate is moving towards NE direction in a collision course with Eurasian plate in the Himalayan region.
While speaking to the media at the online press meet session on the causes of the recent earthquake in North East, Dr. Sandip Kumar Som, Deputy Director-General, Geological Survey of India said, that this oblique collision has developed complex tectonic framework in NE region with several active faults, which gives rise to earthquakes. Plates are moving continuously with certain speeds. Stress and strain accumulates as per the local tectonic/fault environments and ultimately releases when crosses the yield point.
There may be a pertinent question that might be crossing everyone’s mind as to why after 33 years Sonitpur is the epicentre of this huge earthquake (6. 4 in Richter Scale). Actually, Sonitpur lies within a triangular area bounded by E-W trending Atherkhet fault, NW-SE trending Kopilli fault and one N-S trending lineament making the area tectonically complex.
Both the Atherkhet and Kopilli are active. "We do not know about the nature of N-S lineament. This along with oblique convergence of the Indian plate has given repetitive earthquakes in the area. The people might also like to know the reason for water oozing out of the fault at Sonitpur and other adjoining affected areas, the reason for that is the severe liquefaction from unconsolidated substratum that the water from the faults oozes out", he said.
Other than the Atherkhet and Kopilli faults in the Sonitpur region there are four other faults- the Siang fracture, Yemla fault, Namula Thrust and Canyon Thrust which are spread over the North-East region and are active along with Main Himalayan Thrust (MHT), Main Boundary Thrust (MBT), Main Central Thrust (MCT) and other subsidiary faults.
GSI has established a permanent GPS network throughout the country with several stations at NE states to understand strain localisation for future earthquakes. Work towards that is under progress, Som added.
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