Delhi Earthquake

Source: TOI

Context: A 4.0-magnitude earthquake struck Delhi-NCR with its epicentre at Dhaula Kuan, causing strong tremors.

About Earthquakes:

• Definition: An earthquake is a sudden release of energy in the Earth’s crust, causing seismic waves. It occurs due to tectonic plate movements along fault lines.

• Shallow Earthquake: Shallow earthquakes, originating five or 10 kilometres below the surface, tend to cause more damage than those originating deep below the surface.

• Reasons Behind the Delhi Earthquake:

• Seismic Faults: Delhi is near active fault lines, including the Delhi-Hardwar Ridge and Mahendragarh-Dehradun Fault, making it prone to moderate seismic activity. Tectonic Stress: The tremors resulted from stress accumulation and sudden release along these fault lines. Soil Composition: Areas with soft alluvial soil amplify seismic waves, increasing perceived shaking.

• Seismic Faults: Delhi is near active fault lines, including the Delhi-Hardwar Ridge and Mahendragarh-Dehradun Fault, making it prone to moderate seismic activity.

• Tectonic Stress: The tremors resulted from stress accumulation and sudden release along these fault lines.

• Soil Composition: Areas with soft alluvial soil amplify seismic waves, increasing perceived shaking.

• India’s Earthquake Zoning:

• India’s seismic zoning map divides the country into four zones (Zone 2, 3, 4, and 5) based on earthquake risk. Zone 5: Highest seismic activity (e.g., Himalayan region). Zone 4: High risk (e.g., Delhi, Jammu & Kashmir, Bihar). Zone 3: Moderate risk (e.g., Mumbai, Chennai, Kolkata). Zone 2: Low risk (e.g., Deccan Plateau). Delhi falls in Seismic Zone 4, making it highly susceptible to strong earthquakes.

• Zone 5: Highest seismic activity (e.g., Himalayan region).

• Zone 4: High risk (e.g., Delhi, Jammu & Kashmir, Bihar).

• Zone 3: Moderate risk (e.g., Mumbai, Chennai, Kolkata).

• Zone 2: Low risk (e.g., Deccan Plateau).

• Delhi falls in Seismic Zone 4, making it highly susceptible to strong earthquakes.

• Measurement of Earthquakes:

• Richter Scale: Measures magnitude (energy released). Logarithmic scale: Each whole number increase represents 10 times stronger shaking and 32 times more energy release. Modified Mercalli Scale (MMS): Measures intensity (damage & shaking felt). Ranges from 1 (Not Felt) to 12 (Total Destruction). Medvedev-Sponheuer-Karnik (MSK) Scale: Used in India’s seismic hazard map to assess earthquake damage potential.

• Richter Scale: Measures magnitude (energy released). Logarithmic scale: Each whole number increase represents 10 times stronger shaking and 32 times more energy release.

• Measures magnitude (energy released).

• Logarithmic scale: Each whole number increase represents 10 times stronger shaking and 32 times more energy release.

• Modified Mercalli Scale (MMS): Measures intensity (damage & shaking felt). Ranges from 1 (Not Felt) to 12 (Total Destruction).

• Measures intensity (damage & shaking felt).

• Ranges from 1 (Not Felt) to 12 (Total Destruction).

• Medvedev-Sponheuer-Karnik (MSK) Scale: Used in India’s seismic hazard map to assess earthquake damage potential.

• Used in India’s seismic hazard map to assess earthquake damage potential.