Geological fault line offshore of Visakhapatnam

A once repetitively active fracture line or geological fault line to the east of north Andhra Pradesh with maximum activity focussed in the vicinity of offshore Visakhapatnam has been uncovered by a research team from University of Hyderabad (UoH), in collaboration with National Institute of Oceanography and Oil & Natural Gas Corporation Ltd.

Researchers also stated that the fracture line may possibly become active again in future and turn out to be a major coastal hazardous event associated with seismicity and tsunami in and around Visakhapatnam region.

The research team consisting of Prof. K.S. Krishna and Dr. M. Ismaiel from UoH, Dr. K. Srinivas from NIO and Dr. D. Saha from ONGC analysed seismic reflection data in order to address a cause-effect relationship between the sediment load and response of underneath heterogeneous igneous rocks in the Bay of Bengal.

They found a presence of a 300 km long fracture line in the offshore region of north AP and about 100 km away from the coastline. In geological sense the fracture line borders eastern side of the offshore Bastar between the Pranahita-Godavari faultline in the south and Nagavali-Vamshadhara shear zone in the north.

The study concluded that fracture line activity in offshore Krishna-Godavari Basin was variable in nature, to begin with episodic starting at about 16 million years ago and resumed again at 6.8 million years, from there the activity was continuous until 0.3 million years.

Excessive vertical throws (106 and 342 m) occurred at the ages of 16 and 6.8 million years ago over a distance of 300 km in offshore north AP may have triggered the seismicity and prompted the generation of intensive tsunami events. Presently, the fracture line is inactive and may possibly become active whenever the differential stresses on either side of the fracture line reach threshold level and may turn out to be a geohazard event in future.

Timing of future activity is not easy to predict, but the activity will certainly reoccur in a short time in geological sense. This study was reported in a recent issue of Journal of Earth System Science, published by the Indian Academy of Science

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Printable version | Sep 25, 2021 8:01:40 PM | https://www.thehindu.com/news/cities/Hyderabad/geological-fault-line-offshore-of-visakhapatnam/article32132314.ece

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