Reservoir-induced quakes in Koyna to be studied under Rs 470-cr plan

The Union Cabinet on Thursday approved a Rs 470 crore proposal to study reservoir-induced earthquakes in Koyna region of Maharashtra, which experience such tremors way back in 1967.

The study, scientists said, is aimed at finding an earthquake-prediction model for hazard reduction as currently there is no scientific method of predicting an earthquake.

To understand the stress build-up inside the bowels of the earth before the energy is released in the form of a quake, scientists will drill a deep borehole (depth of 6-8 km) through which instruments will be lowered to collect data on earthquake physics. The borehole will come up next to the Koyna dam.

In the Koyna-Warna region of Maharashtra where earthquakes have been occurring in a restricted area of 20x30 sq km for the past five decades, including the big one (6.3 on Richter scale) in December 1967.

Past studies have demonstrated that the area is a natural laboratory to study reservoir-triggered earthquakes, perhaps the best site anywhere in the world.

Though deep boreholes were dug to install underground observatories in Kobe (Japan) and Chi Chi (Taiwan), those tunnels are at the boundaries of tectonic plates and did not yield much information. Koyna, on the other hand, allows drilling in the middle of an intra-plate seismic zone.

“It’s a classical site because of recurrence of quakes for decades, which does not happen in Japan and Taiwan,” Harsh K Gupta, former director of National Geophysical Research Institute, Hyderabad and secretary in the ministry of earth sciences told Deccan Herald.

As a part of the Rs 472.3 crore project, it is planned to set up a research laboratory at Karad, which will serve as the operational centre for carrying out the research activities related to seismic, deep drilling, borehole investigations, core analysis and research in associated fields.

Once the observatory is in place, the researchers will record hundreds of tiny quakes with magnitude of one and more, besides four to five quakes of magnitude 2 and at least five to six quakes of magnitude 3 and above on the Richter scale. They also hope to land at least one magnitude 4 or 5 quake once every two years.

“The aim is to look at every quake beyond 3 on the Richter scale,” said Gupta, currently a member of National Disaster Management Authority.

The experiment has been initially planned for five years involving a large number of institutions and universities.