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Earthquakes in India: Causes, Seismic Zones & Management

Introduction

India moves North-East at about 5 cm/year, colliding with the Eurasian plate. This continuous collision makes the Himalayan region one of the most seismically active zones in the world.

1. Causes: Plate Tectonics

Earthquakes occur due to the release of energy in the Earth's lithosphere that creates seismic waves. The point of origin is the Focus (Hypocenter), and the point directly above it on the surface is the Epicenter.

2. Seismic Waves

• P-Waves (Primary): Fastest. Longitudinal (Sound-like). Can travel through Solid, Liquid, Gas.
• S-Waves (Secondary): Slower. Transverse (Light-like). Cannot travel through Liquid.
• L-Waves (Surface): Slowest but most destructive.

3. Seismic Zones of India

Bureau of Indian Standards (BIS) has grouped the country into 4 zones (Zone I merged with II):

• Zone V (Very High Risk): Entire NE India, parts of J&K, Himachal, Uttarakhand, Rann of Kutch.
• Zone IV (High Risk): Delhi-NCR, Northern Plains.
• Zone III (Moderate Risk) and Zone II (Low Risk) cover the rest.

Conclusion

"Earthquakes don't kill people, buildings do." The key to safety lies in earthquake-resistant construction (NDMA Guidelines).