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Scientists drill 3-km deep inside earth to study risk in earthquake-prone Satara in Maharashtra

The project will use a deep borehole observatory near Koyna Dam to study risk in a stable continental crust, away from the edges of tectonic plates. After factoring in the hardness of the rock and rising temperature, scientists will customise sensors and drilling technology to go 5 km deep.

science Updated: Jul 21, 2017 12:06 IST
Koyna Dam,Shivsagar lake,earthquakes
The earthquakes started in the Koyna-Warna region after a reservoir was created from Shivsagar Lake in 1962. (HT PHOTO)

Scientists in June finished digging a 3-km deep borehole in the earthquake-prone Koyna region in Maharashtra’s Satara district to study reservoir-triggered earthquakes as well as intra-plate ones that occur on a single tectonic plate.

The Koyna-Warna region became earthquake-prone after a reservoir was created from Shivsagar Lake in 1962. Since then, 22 earthquakes of the magnitude of 5 and above on the Richter scale and 400 earthquakes of the magnitude 4 and above have been recorded, including one in 1967 that measured 6.3 on the Richter scale.

All the earthquakes int he region are restricted to an area of 30 km x 20 km and scientists have observed a strong correlation between the earthquakes and the annual loading and unloading cycles of the Koyna and Warna reservoirs.

“When it comes to comprehending these reservoir-triggered earthquakes, there is scientific information missing from near the field. Most of the information is from the surface monitors. The deep drilling project will provide us with the critical missing information,” said Dr Sukanta Roy, director of the Koyna deep-drilling project carried out by Borehole Geophysics Research Laboratory (BGRL), Ministry of Earth Sciences (MoES).

The one of its kind deep-drilling project will use a deep borehole observatory to study earthquakes in a stable continental crust, away from the edges of tectonic plates.

“Deep drilling is usually done for oil extraction in softer sedimentary rocks. This is the first time such drilling is being carried out in a hard, rocky terrain and it is being done for the purpose of research,” said Dr Roy.

The hardness of the rock has also prompted Roy’s team to experiment with a technology that has never been used in the country before – air drilling.

Instead of using traditional drilling fluids, this technology uses compressed air to cool the drill and lift the cuttings from bore to the surface to prevent it from coming in the way of drilling.

This is a pilot for a 5-km borehole that the scientists plan to drill after studying the hardness of the rock, drilling technology required, type of sensors needed and the temperatures that they would encounter. The 5-km drilling project is likely to start by the end of the year.

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First Published: Jul 21, 2017 12:06 IST