India releases new seismic map, places entire Himalayan arc in highest-risk zone, here’s what you need to know
India has published an updated seismic zoning map under the new Earthquake Design Code; This is a significantly revised map showing earthquake-prone areas where the country has placed the entire Himalayan arc as part of the highest-risk Zone VI.
India releases new seismic map and places entire Himalayan arc in highest risk zone
India has published an updated seismic zoning map under the new Earthquake Design Code; This map is a significantly revised map showing earthquake-prone areas where the country places the entire Himalayan arc as part of the highest-risk Zone VI, and has recently influenced how the country understands earthquake vulnerabilities.
What threat does the new map show?
According to a ToI report, as per the new map, around 61% of India’s districts now fall under medium to high risk zones, which will require stricter construction rules and provide greater security in planning in these areas. This change will now affect building construction, major infrastructure and urban expansion, as these need to comply with norms consistent with the constant tectonic pressures beneath these sensitive regions, which are also some of the most populous.
Vineet Gahalaut, director of the Wadia Institute of Himalayan Geology and former director of the National Center for Seismology, said the updated map makes the Himalayan belt more uniform, which is a necessity as it was previously dispersed across Regions IV and V, despite sharing the same tectonic threat.
He emphasized that previous maps ignored risks from fault segments that had not ruptured for a long time, particularly the central Himalayan section, which had not seen any rupture at the surface for almost two centuries. “Previous zoning did not fully account for the behavior of these locked sections that continue to accumulate stress,” he said, adding that the new framework adopts a more scientific, data-driven approach to seismic classification across the region.
The Bureau of Indian Standards (BIS) has released the new map, replacing the previous maps that were entirely based on past earthquake history. The new version uses a scientific method called probabilistic seismic hazard assessment (PSHA).
