Thinking Point
CP Rajendran is a geoscientist and an adjunct professor at the National Institute of Advanced Studies, Bengaluru, and co-author of the book: The Rumbling Earth – The Story of Indian Earthquakes
The Union government is now set to roll back the new seismic code, which was based on what the scientific community has accumulated about earthquakes and their possible impact on India—a genuine attempt to align Indian practice with contemporary global standards.
An earthquake zonation map classifies different regions of India based on their seismic hazard potential. It serves a critical purpose: determining how strong structures must be to withstand earthquakes, thereby guiding building codes and infrastructure planning.
The 2025 revision: A radical update
India released a new revised seismic zonation map in November 2025 under the new Earthquake Design Code (IS 1893:2025), developed by the Bureau of Indian Standards (BIS). This update was based on comprehensive scientific data—including fault systems, maximum-likelihood events, attenuation characteristics, tectonic settings and lithology.
In the previous classification, the Indian landmass was demarcated into four earthquake zones: Zones II, III, IV, and V, with Zone V representing the highest hazard. The updated map in the new classification introduces a new highest-risk Zone VI, reflecting a more nuanced understanding of seismic hazard distribution. The most dramatic change was the creation of a new highest-risk category, Zone VI, placing the entire Himalayan belt and Andaman & Nicobar Islands under India’s top earthquake hazard classification, acknowledging the region’s extreme and previously underestimated seismic potential. This reclassification represents a major scientific advance, aligning India’s hazard assessment with contemporary global standards. It also carries profound implications for construction costs, infrastructure planning and most importantly, public safety across the country’s most seismically vulnerable regions.
Scientific advancements are being reversed
Following the Union Cabinet Secretariat’s advice on Tuesday, the Bureau of Indian Standards (BIS), under the Department of Consumer Affairs, withdrew its November 2025 Gazette notification that revised the country’s earthquake-resistant design standards. The withdrawal specifically targeted the seventh revision of IS 1893 (Part 1): 2025, which included an updated seismic zonation map for India. The intervention followed a February 2026 warning from the Ministry of Housing and Urban Affairs (MoHUA) regarding ‘technical and financial concerns’ of the new code. The Cabinet’s office memorandum said that the revision ‘materially affects the design and execution of ongoing and future infrastructure projects, including those of metro rail projects’. The updated code represented a significant leap toward modern, performance-based seismic design. It introduced fundamental changes to seismic zoning, design spectra, stiffness requirements, dual system provisions and geotechnical evaluations. This revision was driven by advanced Probabilistic Seismic Hazard Assessment (PSHA) methodologies, integrating historical seismicity, active faults and other parameters to generate more realistic estimates of seismic activity. The scientific community recognised that 61% of India’s land area, where around 75% of the population lived, was prone to moderate to strong tremors. The new map finally put data and lived experience on the same page.
The financial argument that won
The construction lobby welcomed the decision to withdraw the new seismic zonation map. Developers argued that switching standards mid-stream for projects in advanced planning was ‘technically unfeasible’ and would spike construction costs by 20%. In Ahmedabad alone, approximately 15 major high-rise projects were stalled due to the new requirements.
The cost implications were substantial. The updated code increases base shear demands by 10–30 per cent, tightens irregularity provisions, and mandates more complex analyses. For metro and other public infrastructure projects, costs could rise by 30% to 50% across metro cities. The Cabinet noted that the code was ‘introduced without structured consultation with metro rail corporations’.
Uneven implementation preceded withdrawal
Before the withdrawal, the implementation had already created chaos. Municipal corporations in Gujarat adopted wildly different approaches. The Ahmedabad Municipal Corporation insisted on immediate compliance, stalling projects. Meanwhile, Surat, Vadodara and Rajkot continued approving projects under the 2016 code, citing a six-month transition window. Developers in Ahmedabad protested that the city’s insistence was ‘inconsistent with the Centre’s transition provision’.
The reversal means reverting to the 2016 standard, abandoning meaningful improvements that would have made India’s infrastructure genuinely safer. The new code included:
1. A fully revised earthquake zoning map based on probabilistic hazard assessment
2. Updated design spectra defining ground motion up to 10 seconds
3. Comprehensive soil-structure interaction provisions
4. Improved liquefaction evaluation procedures
5. Clearer rules for structural systems based on seismic zones
For the tectonically fragile areas of the Himalayan and Andaman- Nicobar arc, where major government-sponsored infrastructural projects are being implemented, this reversal means continued construction under standards that may be inadequate for the seismic reality the region faces.
Consider the implications for one of India’s most ambitious and controversial infrastructure projects: the massive transhipment port being planned in Galathea Bay, Great Nicobar Island. Under the now-withdrawn 2025 seismic code, the entire project site is placed in the newly created Zone VI—the highest-risk category, acknowledging the region’s extreme seismic hazard. With the code gone, the builders are no longer required to follow the standards that Zone VI would have demanded. They can downplay seismic risk, citing a withdrawn notification and continue construction under the less stringent 2016 standards—in a region that scientists explicitly warn is unsuitable for such infrastructure.
A construction industry spokesperson, hailing the withdrawal, said that the new codes were prepared ‘without consultation with stakeholders’. But this defence only raises a more fundamental question: When it comes to life-safety standards, where the stakes are measured not in rupees but in human lives, should stakeholder consultation, meaning builders concerned about costs, trump scientific consensus about earthquake risk?
The government has directed that consultations with stakeholders be completed before any further steps are taken. Yet there is no parallel call for consultation with the scientific community whose decades of research informed the now-abandoned code. Seismologists, earthquake engineers and hazard assessment experts, the very people whose knowledge underpinned this progressive safety standard, have been conspicuously absent from the discussions that led to its withdrawal.
India must now continue building to 2016 standards, in a world where the scientific understanding of seismic risk has advanced considerably. The bold policy was withdrawn. The science remains. And we still do not know why this reversal was executed without discussions with the scientists who know the risk best. In a country where 75% of the population lives in earthquake-prone zones, whose voice should carry greater weight, the builder counting costs, or the scientist counting lives?
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