India Unveils New Seismic Map, Puts Entire Himalayan Arc in Highest-Risk Zone VI

India has released a new seismic zonation map under the 2025 Earthquake Design Code, placing the entire Himalayan arc in the highest-risk Zone VI. The updated map shows 61% of India now lies in moderate to high hazard zones.

India has released a major new seismic zonation map that changes how the country understands earthquake danger. The map is part of the updated 2025 Earthquake Design Code, and it places the entire Himalayan arc in the highest-risk category, Zone VI, for the first time. The update also shows that 61% of India now falls under moderate to high hazard zones, which means stricter building rules and safer planning will be required across many states, according to a report by The Times of India.

This change marks one of the most important updates to India’s earthquake safety planning in decades.

A major shift in how India understands earthquake danger

The new map was released by the Bureau of Indian Standards (BIS). It replaces older maps that relied heavily on past earthquake history. The new version uses a scientific method called probabilistic seismic hazard assessment (PSHA). This method includes:

• Detailed active fault data
• Maximum expected earthquake size on each fault
• How shaking reduces with distance
• Tectonic features
• Type of rock and soil under towns and cities

The older map depended on previous earthquake records, basic soil types and damage reports. Experts say that approach often led to errors, especially in regions with fewer recorded earthquakes but strong hidden faults.

Under the new rules, any town located between two different zones will automatically be placed in the higher-risk zone. This ensures no place is underestimated in terms of danger.

Himalayan region now fully placed in Zone VI

For years, the Himalayan belt was split between Zones IV and V, even though the whole region sits on the powerful Indian-Eurasian plate boundary. Scientists said this division was misleading and did not match the real tectonic threat.

Vineet Gahalaut, director of the Wadia Institute of Himalayan Geology and former director of the National Centre for Seismology, explained to the TOI that the change brings long-needed uniformity.

He said older zonation systems did not fully consider locked fault segments. These are parts of the fault that have not ruptured for a long time and continue to store dangerous levels of stress. The central Himalaya, for example, has not seen a major surface-rupturing quake in nearly 200 years, making it a high-risk zone.

Scientists told TOI that the new map clearly marks the outer Himalaya as a region where earthquake ruptures can move southwards until they reach the Himalayan Frontal Thrust. In the Dehradun area, this thrust begins near Mohand, bringing better clarity and consistency across the entire corridor.

61% of India in moderate to high seismic hazard

The new map shows that a huge part of the population is at risk from earthquakes. India has many large cities, crowded towns and rapid construction zones in these unsafe regions.

BIS said that nearly three-fourths of Indians now live in active seismic zones. The new classification increases the moderate-to-high hazard area from 59% to 61%. This rise means engineers, builders and governments will have to follow stricter rules when approving or designing new buildings or bridges.

New building rules under Earthquake Design Code 2025

The updated design code brings several new safety requirements for buildings and infrastructure. These rules apply not just to the structure of a building but also to items inside and outside that may fall, break or injure people during shaking.

Focus on non-structural parts

For the first time, the code gives strong attention to non-structural components, including:

• Parapets
• Ceilings
• Overhead tanks
• Panels and façade elements
• Lifts
• Electrical lines
• Hanging fixtures

These items often break in even moderate earthquakes. Under the new rules, any heavy non-structural item weighing more than 1% of the building’s total weight must be properly anchored so it does not fall.

Engineers say this will greatly reduce injuries during medium-strength earthquakes.

Stronger standards near active faults

Buildings built close to major faults must now consider pulse-like ground motions, which are severe, sudden movements that happen near the source of a quake. The code includes new limits and checks related to:

• Building displacement
• Ability to bend without breaking (ductility)
• How much energy the building can absorb
• Liquefaction and soil flexibility included

The norms also include provisions for:

• Liquefaction (when soil behaves like a liquid during strong shaking)
• Soil flexibility
• Site-specific ground response

This ensures that buildings respond to the actual ground conditions below them, rather than using common assumptions for entire districts.

Special rules for critical infrastructure

Important facilities will now need stronger protection. These include:

• Hospitals
• Schools
• Bridges
• Pipelines
• Large public buildings

Such structures must remain fully functional after a major earthquake. This requirement, experts say, brings India closer to global standards, where the focus is on resilience and emergency service continuity rather than only preventing collapse.

'Exposure window' added for the first time

A major new feature of the 2025 map is the probabilistic exposure and multi-hazard assessment (PEMA) method. This approach considers:

• Population density
• Concentration of infrastructure
• Socioeconomic vulnerability

This means the map does not only show the physical hazard but also the likely human and economic impact. Urban areas with dense construction now get a clearer risk assessment, even if the shaking level is moderate.

Southern India sees minor changes

While the Himalayan region went through major reclassification, the southern peninsula saw small scientific refinements. Experts say the south has a more stable tectonic pattern, so its overall hazard levels stay fairly similar to earlier versions.

India has seen some of the world's deadliest earthquakes, from the 1905 Kangra quake to the 2001 Bhuj disaster. Many of the country's biggest cities lie near active faults. With rapid urbanisation, the risk to lives, buildings and infrastructure increases each year.

The new seismic zonation map and design code aim to create safer future cities by ensuring better planning, stronger structures and a clearer understanding of local hazards.