New seismic map shifts Himalayan region into high-risk earthquake zone

India has released a revised seismic hazard map as part of an updated Earthquake Design Code, marking a major overhaul in earthquake risk assessment. For the first time, the entire Himalayan region has been classified into the newly introduced highest-risk Zone VI, reflecting the region’s increasing vulnerability. This update, one of the most substantial shifts in seismic policy in decades, now places more than 60% of the country under moderate to high earthquake risk zones. Previously, the Himalayan arc was split between Zones IV and V, but the new approach offers a unified risk profile for the region, which had previously been underestimated due to the long absence of major earthquakes along fault lines, especially in the central Himalayas.

Why the Himalayas are a danger zone?

The Himalayas are classified as the highest seismic risk zone due to their position on one of the most active tectonic plate boundaries in the world. The Indian Plate is slowly moving northward at a rate of approximately 5 cm per year, colliding with the Eurasian Plate. This ongoing collision not only formed the Himalayas but continues to push the mountain range upward, causing significant stress beneath the Earth’s surface. When this stress is released, it results in powerful earthquakes.

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Additionally, the geological youth of the region means the rocks are still adjusting, with frequent folding and breaking, which contributes to the instability of the area. Several large fault systems, including the Main Frontal Thrust and Main Central Thrust, are found beneath the Himalayas and are capable of producing devastating earthquakes. The region also has several seismic gaps, areas where major earthquakes have not occurred for centuries—indicating that significant energy has accumulated and is due for release.

What's new in the revised zonation?

The updated seismic map takes into account new data about earthquake risk, including the potential for rupture propagation along the Himalayan Frontal Thrust, which extends the danger zones into areas like Dehradun. Key changes also involve reclassifying regions in the outer Himalayas, where fault lines could trigger earthquakes that impact populated foothill areas.

In this new map, boundary towns between seismic zones are now automatically classified into the higher-risk zone, ensuring that geological realities are prioritized over administrative borders. This shift ensures that cities, towns, and infrastructure in vulnerable regions are designed with stricter engineering standards to minimize earthquake damage.

The updated map reflects the ongoing tectonic activity between the Indian and Eurasian plates, particularly in densely populated regions like Uttarakhand, Himachal Pradesh, and parts of Uttar Pradesh. As a result, the map calls for urgent retrofitting of existing infrastructure, halting urban development on soft sediments or near active faults, and heightened awareness for earthquake preparedness. Experts praise this uniform approach as a critical step toward improving disaster resilience, especially as urbanisation continues to expand in these seismic hotspots. The new map, based on advanced modeling techniques, is a call to action for recalibrating India’s preparedness for seismic events across the nation.