Why is India drilling a 6-km deep hole in Maharashtra?

• cientists 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.

What is scientific deep drilling?

• Scientific deep-drilling is the enterprise of strategically digging boreholes to 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, and more.

Benefits of a deep-drilling mission

• Earthquakes are challenging to study. Surface-level observations can’t make complete sense of them.
• The recurrent earthquakes in Koyna are synchronous with the dam’s loading and unloading during the monsoon and post-monsoon periods, offering an opportunity to widen our understanding of earthquakes.
• Scientifically drilled boreholes can be a hub of direct, unique in situ experiments and observations and monitor a region’s fault lines and seismic behavior.
• They also provide exact and fundamental knowledge of the composition of the earth’s crust, structure, and processes, and help validate models based on surface studies.
• Thus, it can inform a range of societal problems related to geohazards and geo-resources.
• Investing in scientific deep-drilling can also help expand scientific know-how and technological innovation, especially in seismology (the study of earthquakes).
• It can also spur the development of tools and equipment for drilling, observation, data analysis, sensors, etc.
• Scientific deep drilling is the best tool to study the earth’s interior. Other ways include geophysical measurements of seismic wave speed, gravitational and magnetic fields, and electrical conductivity from the near surface. Scientists can also examine crust fragments brought from deep underground to the surface.
• But scientific deep-drilling remains the most reliable method because it helps get direct (in situ) and near-source measurements. The earth’s interior is a hot, dark, high-pressure region that hinders long and continuous operations.
• Aside from earthquakes, this is because many surface phenomena, the composition of water and air, their availability, and the resulting interactions with climate-affected phenomena are linked to what happens inside the earth’s crust.

What have scientists found?

• The pilot drilling mission was a success and has yielded significant new information about the subsurface geological environment.
• For one, it revealed 1.2-km thick, 65 million-year-old Deccan trap lava flows, and below them 2,500-2,700-million-year-old granitic basement rocks.
• Downhole measurements of core samples and conditions from a depth of 3 km have also provided new information about the physical and mechanical properties of rocks, the chemical and isotopic composition of formation fluids and gasses, temperature and stress regimes, and fracture orientations.
• It is expected that these experiments will be useful for many years, especially to understand the reasons for recurrent earthquakes in specific geographies.
• In sum, the Koyna exercise is establishing a firm footing in scientific deep-drilling for India. Its lessons will inform future deep-drilling experiments and expand academic knowledge in multiple ways.