Context: The Borehole Geophysics Research Laboratory (BGRL) in Karad, Maharashtra, is a specialised institute mandated to execute India’s scientific deep-drilling programme. Under BGRL, the aim is to drill the earth’s crust and conduct scientific observations to help expand our understanding of reservoir-triggered earthquakes in the Koyna-Warna region
About Project
Purpose of Deep Drilling in Maharashtra
- Location: Koyna-Warna region, Maharashtra
- Institute: Borehole Geophysics Research Laboratory (BGRL), Karad, under Ministry of Earth Sciences (MoES)
Objectives:
- Conduct scientific deep drilling to a depth of 6 km in the earth’s crust.
- Study reservoir-triggered earthquakes in the Koyna-Warna region.
Scientific Deep Drilling Overview
- Definition: Strategically digging boreholes to analyse deeper parts of the earth’s crust.
- Benefits: Provides insights into earthquakes, earth’s history, rock types, energy resources, climate change patterns, etc.
Scientific Deep Drilling:
- Considered the most effective method to study the Earth’s interior.
- Provides direct, in situ measurements from deep within the Earth.
- Allows retrieval of rock and sediment cores that align with Earth’s geological timeline.
Other Methods of Study:
- Geophysical Measurements:
- Seismic wave speed: Provides insights into the structure and composition of Earth’s interior.
- Gravitational and magnetic fields: Indicate variations in density and magnetic properties.
- Electrical conductivity: Reflects the presence of fluids and minerals.
Challenges of Scientific Deep Drilling:
- Technical Challenges:
- Operates in a hot, dark, high-pressure environment.
- Requires advanced drilling technology and equipment.
- Logistical Challenges:
- Labor-intensive and capital-intensive.
Key Findings from the Pilot Drilling Mission at Koyna:
- Subsurface Geological Environment:
- Discovered 1.2-km thick Deccan trap lava flows dating back 65 million years.
- Revealed granitic basement rocks aged between 2,500 to 2,700 million years below the lava flows.
- Downhole Measurements and Core Analysis:
- Conducted measurements and extracted core samples from a depth of 3 km.
- Provided new insights into:
- Physical and mechanical properties of rocks.
- Chemical and isotopic composition of formation fluids and gases.
- Temperature and stress regimes.
- Fracture orientations.
- High-Resolution Imaging Techniques:
- Used acoustic and micro-resistivity methods to capture detailed images of the borehole wall.
- Validated data extracted from cores, enhancing reliability for global comparisons.
- Hydraulic Fracturing Experiments:
- Conducted experiments to directly measure stress regimes in the rocks.
- Data expected to contribute significantly to understanding seismic activity in the region.
- Detection and Study of Fault Zones:
- Integrated various datasets to detect buried fault zones and study their properties.
- Presence of Water and Stress Conditions:
- Discovered water presence down to 3 km depth, identified as meteoric or rain-fed.
- Suggests deep percolation and circulation mechanisms.
- Found that the Koyna region is critically stressed, indicating susceptibility to small stress perturbations that could trigger frequent, small-magnitude earthquakes.
Future Implications and Utilization of Koyna Pilot Data:
- Temperature Modelling and Equipment Design:
- Predicted temperature at 6 km depth: 110-130 degrees C.
- Future drilling equipment and downhole data acquisition systems need to be designed to withstand these conditions.
- Facilitation of New Experiments:
- Koyna data and samples will facilitate numerous new experiments.
- Over 20 research groups across India are currently studying Koyna samples.
- Research Areas and Studies:
- Fault Zone Gouge Analysis:
- Studying gouges from fault zones to understand frictional properties in quake-prone regions.
- Microbial Characterization:
- Characterizing microbes on rocks to understand life forms in hot, dark, nutrient-poor environments.
- Potential for discovering new molecules and improving industrial processes.
- Fault Zone Gouge Analysis:
- International Collaboration:
- International geological research community seeking access to core samples.
- Projects include emerging fields like carbon capture and storage in the deep Deccan traps.
- Impact of Koyna Exercise:
- Establishing India’s presence and capability in scientific deep drilling.
- Lessons learned will inform and shape future deep-drilling endeavors.
- Expanding academic knowledge across various disciplines.
Earthquake, any sudden shaking of the ground caused by the passage of seismic waves through Earth’s rocks.
Causes of earthquake
Major causes of earthquake are natural and occur mostly around the plate boundaries due to continuous interaction of plates.
Natural causes
- Tectonics: tectonic movements associated with plate boundaries are ruptures and faults along the constructive plate boundaries, folding and faulting along the destructive plate boundaries, this sort of disequilibrium caused due to different types of plate movement and consequently earthquakes of varying degree are caused.
- Volcanic: Explosive violent gases during process of vulcanicity try to escape upwards and hence they push the crustal surface from below with great force and thus is caused severe earth tremor of high magnitude. Example-Krakatoa volcano of Indonesia caused intense earthquakes.
Anthropogenic causes
Earthquakes are induced by human activities causes earth tremors of serious consequences.
- Fracking: Injection of fluids into deep wells (Fracking)- can lubricate existing faults and crack rocks, triggering earthquakes.
- Underground nuclear explosions: Detonation of large underground nuclear explosions-will accentuate the fault lines leads to earthquakes. Case study– North Korea’s 2017 nuclear bomb test set off aftershocks that lasted for about eight months after the explosion. The bomb was set off near a previously unmapped fault line, and a first produced a 6.3 earthquake, followed by a magnitude 4 quake just minutes later.
- Mining: rocks and other materials are being removed from the Earth that instability in the ground is occurring, which is triggering earthquakes.
Reservoir induced earthquake: Earthquake triggered by the impoundment of water behind the dam of enormous quantity causes isostatic disequilibrium of already adjusted rocks or further augment the already isostatically adjusted rocks below the reservoir or further augment the already fragile structures due to faults and fractures underneath. Examples Koyna dam in India, Hoover dam in USA.
Previous year questions (2023)
Q. Consider the following statements:
1. In a seismograph, P waves are recorded earlier than S waves.
2. In P waves, the individual particles vibrate to and fro in the direction of wave propagation whereas in S waves, the particles vibrate up and down at right angles to the direction of wave propagation.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Ans: (c)
Practice questions
Q. With reference to deep drilling project, consider the following statements:
1. It is an indirect method to study earth’s interior.
2. The Koyna region is under significant stress and prone to earthquakes.
3. It is conducted by the Borehole Geophysics Research Laboratory under the Ministry of Environment, Forest and Climate Change.
How many of the statements given above are correct?
(a) Only one
(b) Only two
(c) All three
(d) None of the above
Ans: (a)
Explanation:
Scientific Deep Drilling:
- Considered the most effective method to study the Earth’s interior.
- Provides direct, in situ measurements from deep within the Earth.
- Allows retrieval of rock and sediment cores that align with Earth’s geological timeline.
Found that the Koyna region is critically stressed, indicating susceptibility to small stress perturbations that could trigger frequent, small-magnitude earthquakes.
Purpose of Deep Drilling in Maharashtra
- Location: Koyna-Warna region, Maharashtra
- Institute: Borehole Geophysics Research Laboratory (BGRL), Karad, under Ministry of Earth Sciences (MoES)