India’s mission to drill a 6-km deep hole in Koyna, Maharashtra | Explained

Scientific deep-drilling in Koyna, India, offers unique insights into earthquakes, geological history, and technological innovation in earth sciences.

Of all that we have been studying about the earth, earthquakes remain among the least understood. Scientists don’t yet have a way to predict when and where an earthquake will occur.

We know powerful earthquakes at the boundaries of tectonic plates, which measure more than 7.5 on the Richter scale, are almost certainly associated with a severe loss of infrastructure and life. In the ocean, these geological events trigger tsunamis. However, more minor earthquakes that occur in a plate’s interior are more challenging to predict because they occur at the least expected sites and could strike densely populated habitats.

This is why scientific deep drilling is an indispensable tool for progress in the earth sciences. Countries like the U.S., Russia, and Germany conducted such scientific projects in the 1990s. Recently, in 2023, there were reports of China undertaking a deep-drilling mission of its own.

Scientific deep-drilling is the enterprise of strategically digging boreholes to observe and analyse deeper parts of the earth’s crust. It offers opportunities and access to study earthquakes and expands our understanding of the planet’s history, rock types, energy resources, life forms, climate change patterns, the evolution of life, and more.

The Borehole Geophysics Research Laboratory (BGRL) in Karad, Maharashtra, is a specialised institute under the Ministry of Earth Sciences of the Government of India mandated to execute India’s sole scientific deep-drilling programme. Under BGRL, the aim is to drill the earth’s crust to a depth of 6 km and conduct scientific observations and analysis to help expand the understanding of reservoir-triggered earthquakes in the active fault zone in the Koyna-Warna region of Maharashtra.

This region has been experiencing frequent and recurrent earthquakes since the Shivaji Sagar Lake, or the Koyna Dam, was impounded in 1962. BGRL’s pilot borehole — to a depth of 3 km in Koyna — is complete, and the Ministry of Earth Sciences is committed to completing the task of reaching a depth of 6 km.

Earthquakes are challenging topics of study. Surface-level observations don’t suffice to understand them completely. The recurrent earthquakes in Koyna are synchronous with the dam’s loading and unloading during the monsoon and post-monsoon periods, offering a unique opportunity to widen our understanding of earthquakes and to use the resulting knowledge for scientific and public good.