Earthquake Zoning Revision in India

The Centre's recent rollback of the Bureau of Indian Standards (BIS) revision to India's earthquake zoning follows a significant challenge to the methodology, deemed by some engineers as incompatible with site-based evaluations. This decision holds substantial implications for urban planning, disaster preparedness, and climate resilience.

Importance of Accurate Zoning

• Disaster and climate-proofing of cityscapes, power infrastructure, dams, highways, and residential and commercial buildings as India expands urban infrastructure.
• The zoning framework is crucial for preparedness against possible earthquakes and their intensities.

Global Standards and India's Approach

• Globally, advanced economies and seismically active regions employ the Probabilistic Seismic Hazard Assessment (PSHA), using probability-based simulations of ground motion.
• India has historically used a simpler fixed zoning model, and the BIS's shift towards PSHA is directionally accurate but faced opposition.

Controversial Zoning Revisions

• The proposed revisions included a new Zone VI for high-risk areas like Kashmir, parts of the Himalayan belt, Kutch, and the north-east.
• Concerns arose that stringent zoning could hinder developmental activities in economically vulnerable regions and push more housing into the informal sector, which already constitutes about 80% of homes in India.
   
  • Cost implications: A one-zone increase could raise costs by approximately 20%, while a two-zone increase could raise costs by nearly one-third. 
• Higher cost implications for major infrastructure projects like metro systems, dams, and power stations.

Opposition and Wider Consultation Needs

• Pushback from the private sector and government bodies, including the Ministries of Housing and Urban Affairs, Home Affairs, the Central Water Commission, and the National Dam Safety Authority.
• The construction sector, a significant contributor to carbon emissions, necessitates a revision that balances disaster resilience, climate mitigation, affordability, and execution challenges.
• A holistic consultation across ministries, regulators, and industry stakeholders is essential for developing an implementable framework.