With 61% of India now high-risk, new quake map pushes Himalayan belt into highest danger category

 

India has released a sweeping new seismic zonation map under the revised Earthquake Design Code issued by the Bureau of Indian Standards (BIS), placing the entire Himalayan arc in a newly created Zone VI the highest seismic risk category ever assigned in the country. The overhaul marks one of the most consequential updates to India’s hazard assessment in decades, showing that 61% of the nation is now classified in moderate to high seismic zones.

Under the old system, the Himalayan belt was split across Zones IV and V despite facing uniform tectonic hazards. Experts say earlier maps understated threats from long-dormant but highly capable fault segments, particularly in the central Himalayas, which have not experienced a major surface-rupturing earthquake in nearly 200 years.

Why the Himalayas fall in the highest danger zone

The Himalayas straddle one of the world’s most forceful tectonic collision boundaries. The Indian Plate continues to push into the Eurasian Plate at nearly five centimetres per year — the same collision that formed the mountain range and still drives it upward. This constant compression builds enormous stress in the Earth’s crust. When that stress releases, it produces some of the planet’s most powerful earthquakes.

The region’s young, actively deforming geology amplifies instability. Beneath the range lie major fault systems — the Main Frontal Thrust, Main Boundary Thrust, and Main Central Thrust — each capable of triggering significant earthquakes. Scientists have also identified several seismic gaps where large events have not occurred for centuries, signalling substantial accumulated strain.

What’s new in the revised map

The update incorporates advanced modelling that accounts for southward rupture propagation along the Himalayan Frontal Thrust, extending hazards into areas such as Dehradun near Mohand. The outer Himalaya has been reclassified due to the potential for faults to generate quakes that cut into the densely populated foothills.

Boundary towns positioned between previous zones will now automatically fall under the higher-risk classification. BIS officials say the shift aligns zonation with geological realities rather than administrative boundaries — a change that directly impacts building codes, infrastructure design and long-term urban planning.

The new map underscores the ongoing Indian–Eurasian plate collision and the resulting stress beneath populated states including Uttarakhand, Himachal Pradesh and parts of Uttar Pradesh. It also calls for retrofitting vulnerable infrastructure and halting construction on soft sediments or near active faults. Experts have welcomed the uniformity, describing it as an essential step toward long-term resilience as urbanisation accelerates.

Driven by enhanced data and modelling, the revised zonation compels a nationwide recalibration of disaster preparedness.