Distribution of Earthquake Zones in India.
India is highly prone to seismic activity due to its unique tectonic setting, primarily the ongoing northward movement of the Indian Plate and its collision with the Eurasian Plate. About 59% of India’s landmass is vulnerable to earthquakes of varying intensities. The Bureau of Indian Standards (BIS) has classified the country into four seismic zones based on the Modified Mercalli (MM) intensity scale.
1. Seismic Zone Classification
| Zone | Intensity (MSK Scale) | Description | Major Regions Covered |
|---|---|---|---|
| Zone V | IX or higher | Very High Damage Risk | Kashmir, Western & Central Himalayas, North-East India, Rann of Kutch, and Andaman & Nicobar Islands. |
| Zone IV | VIII | High Damage Risk | Ladakh, Himachal Pradesh, Uttarakhand, Delhi, Sikkim, Indo-Gangetic plains (Northern Bihar/UP), and parts of Gujarat/Maharashtra. |
| Zone III | VII | Moderate Damage Risk | Kerala, Goa, Lakshadweep, remaining parts of UP, Punjab, Rajasthan, Madhya Pradesh, and Coastal Odisha. |
| Zone II | VI or lower | Low Damage Risk | Major parts of the Peninsular Plateau (stable shield), including large parts of Rajasthan and Central India. |
2. Key Seismic Belts in India
- The Himalayan Belt: A 2,400 km stretch of high-intensity activity caused by continental collision. It is the most dangerous zone, capable of earthquakes exceeding 8.0 magnitude.
- The Alpine-Himalayan Belt: Extends through the North-East and the Andaman-Nicobar Islands (subduction zone).
- Intra-plate Seismic Zones: Areas like Latur (1993) and Kutch (2001) prove that even "stable" peninsular regions can experience major quakes due to local fault reactivation.
3. Seismic Vulnerability of Odisha
Odisha primarily falls under Zone II and Zone III. While the state is generally considered stable compared to the Himalayas, the Mahanadi Graben and certain coastal areas are susceptible to moderate tremors. Historical activity around the Brahmani-Baitarani fault lines suggests a need for earthquake-resistant building codes in urban centers like Bhubaneswar and Cuttack.
Conclusion
In conclusion, the distribution of earthquake zones in India highlights a clear gradient from the tectonically violent North to the relatively stable South. However, increasing urbanization in Zone IV and V cities like Delhi and Guwahati makes seismic retrofitting and disaster preparedness a national priority. For your exam, remember that "Zone I" no longer exists in the current BIS classification; it has been merged with Zone II.