Seismic Hazard Zones of India

Seismic hazard zones of India

How to Approach

This question requires a descriptive answer outlining the seismic hazard zones of India. The approach should involve defining seismic hazard, explaining the factors influencing it in India, detailing the five zones with their characteristics (intensity, earthquake probability), and briefly mentioning mitigation strategies. A map-based description would be ideal. The answer should be concise, sticking to the 150-word limit, and focus on providing factual information.

Model Answer

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Introduction

India is prone to earthquakes due to its location in a seismically active region, resulting from the collision of the Indian and Eurasian plates. The country is divided into five Seismic Hazard Zones (I to V), based on the Modified Mercalli Intensity Scale, which assesses the potential for ground shaking. This zonation, as per the Indian Standards IS 1893:2016 (Part 1), is crucial for earthquake-resistant design and disaster preparedness. Understanding these zones is vital for minimizing seismic risk across the nation.

The zones are categorized based on expected earthquake magnitude and frequency:

Zone V (Very High Damage Risk): Includes areas like Northeast India, parts of Gujarat, Andaman & Nicobar Islands. Highest intensity, frequent earthquakes.
Zone IV (High Damage Risk): Covers regions like Jammu & Kashmir, Himachal Pradesh, Uttarakhand, Delhi, Sikkim, North Bihar, West Bengal. Significant earthquake probability.
Zone III (Moderate Damage Risk): Encompasses areas like Kerala, Goa, Maharashtra, Rajasthan, Madhya Pradesh, Uttar Pradesh, Haryana, Punjab. Moderate earthquake potential.
Zone II (Low Damage Risk): Includes regions like Karnataka, Tamil Nadu, Andhra Pradesh, Telangana. Low earthquake probability.
Zone I (Very Low Damage Risk): Comprises areas with minimal seismic threat.

Factors Influencing Seismic Hazard

Several factors contribute to India’s seismic vulnerability:

Plate Tectonics: The ongoing collision of the Indian and Eurasian plates.
Fault Lines: Presence of numerous active fault lines across the country.
Geological Structure: Varied geological formations and soil conditions.

Mitigation efforts include earthquake-resistant building codes, early warning systems, and public awareness campaigns.

Conclusion

The seismic hazard zonation of India is a critical tool for disaster management and infrastructure planning. Effective implementation of building codes and preparedness measures, tailored to each zone’s specific risk level, are essential to minimize potential damage and loss of life. Continuous monitoring, research, and public education are crucial for enhancing India’s resilience to earthquakes.

Answer Length

This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.

Additional Resources

Key Definitions

Seismic Hazard

The probability that a particular location will experience ground shaking of a certain intensity due to an earthquake.

IS 1893:2016 (Part 1)

Indian Standard code of practice for earthquake-resistant design of structures. It provides guidelines for assessing seismic hazards and designing buildings to withstand earthquake forces.

Key Statistics

Approximately 59% of India’s land area is vulnerable to earthquakes of magnitude 6 or more.

Source: National Disaster Management Authority (NDMA), 2023 (Knowledge Cutoff)

India experiences approximately 20,000 earthquakes annually, most of which are of low intensity.

Source: Earthquake Monitoring Research Centre (EMRC), 2022 (Knowledge Cutoff)

Examples

Gujarat Earthquake 2001

The 2001 Gujarat earthquake (magnitude 7.7) highlighted the vulnerability of buildings in Zone V and led to revisions in building codes and disaster management strategies.

Frequently Asked Questions

▶What is the Modified Mercalli Intensity Scale?

It measures the intensity of an earthquake based on its observed effects on people, structures, and the natural environment, rather than the earthquake's magnitude.

Seismic hazard zones of India

Model Answer

Introduction