Seven kilometres hole to study Western Ghats quakes

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India will be the first country in the world to deepdrill a borehole 7 km deep in order to understand the mechanics of earthquakes faulting in the seismically sensitive Koyna-Warna region in the Western Ghats.

A deep borehole was drilled in the San Andreas Fault in California in the US but that went down to a depth of only 3 km.

This deep scientific drilling into the earthquake zone of Koyna-Warna region has been initiated by scientists from the National Geophysical Research Institute (NGRI) who point out that the this deep-drill hole will help study earthquakes in a stable continental crust unlike the deep borehole drilled on a plate boundary fault in California.

Dr N. Purnachandra Rao, who is heading this project, pointed out that the Koyna-Warna region was known for Reservoir Triggered Seismicity (RTS) and earthquakes occur regularly in an area of 20x 30 sq. km ever since the Koyna reservoir was created in 1962.

The largest earthquake that occurred here has had an intensity of 6.3 magnitude on the Richter scale but hundreds of smaller earthquakes are being recorded here all the time.

A seismic network of 15 sensors operating in that region for the last six years helped scientists to zero down on this area. The ministry of earth sciences has signed an MoU with the German Research Centre for Geosciences to assist in this project for a period of five years at a likely cost of Rs300 crores.

Environmentalists are up in arms against this project because some of the proposed drilling sites are in the Sahyadri Tiger Reserve. They believe drilling bores will destroy the only tiger reserve to be found in the northern part of the Western Ghats.

Meanwhile, S.W.H. Naqvi, principal chief conservator of forests (wildlife), Maharashtra, has forwarded the letter from the NGRI to the National Tiger Conservation Authority, which, in turn, has forwarded it to the National Board for Wildlife. Senior officials in the forest department have expressed reservations about these drilling operations though Mr Rao has clarified that the next two years will be spent in trying to locate a feasible site.