India Earthquake Zoning Map Revision: PSHA Method and BIS Seismic Zones Debate

The Union Government rolled back the proposed revision of India’s earthquake zoning map prepared by the Bureau of Indian Standards (BIS)  due to concerns over its methodology and potential increase in infrastructure and construction costs.

• Until now, India has primarily used a simpler fixed zoning model and the Bureau of Indian Standards (BIS) plans to adopt a global framework such as Probabilistic Seismic Hazard Assessment (PSHA).
• Institutional Pushback: Concerns were raised by:

• • Ministry of Housing and Urban Affairs
  • Ministry of Home Affairs
  • Central Water Commission
  • National Dam Safety Authority

About Earthquake Zoning

• Earthquake zoning divides the country into seismic zones based on the intensity and probability of earthquakes.
• It helps determine building design standards, disaster preparedness, and infrastructure planning.
• BIS currently classifies India into four seismic zones (II, III, IV and V) based on earthquake risk.

Proposed Changes

• The BIS revision attempted to introduce a new high-risk seismic category – Zone VI.
• Regions proposed to be included:
• • Most of Kashmir
  • Parts of the Himalayan belt
  • Kutch region in Gujarat
  • Parts of North-East India

Concerns

• Impact on Urban Development: Urban planners worry that such zoning could stall developmental and infrastructure activity in already economically fragile regions.
  • Such planning can potentially push more housing into the informal sector  which already accounts for nearly 80% of India’s homes. 
• Higher Construction Costs: Estimates suggest that a one-zone increase could raise costs by around 20%, and two zones by nearly one-third. 
  • For major infrastructure such as metro rail systems, dams and power stations, the cost implication could be significantly higher.
• Climate and Infrastructure Implications: The construction sector is a major source of carbon emissions in India.
  • Stricter seismic design may increase material use (cement, steel), raising costs and emissions.

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Earthquake Zoning Revision: Significance

• The earthquake zoning revision is important because India is:
• Rapidly expanding urban infrastructure.
• Building metros, highways, dams, and power infrastructure in seismically active regions.
• Facing increasing disaster risks due to climate change and urbanisation.

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