Gangtok, Dec 1 : India’s updated seismic zonation map under the revised Earthquake Design Code has placed the entire Himalayan arc, including Sikkim, in the highest seismic vulnerability category, Zone VI. The shift marks a significant change in how earthquake threats are assessed nationally, especially for the Northeast where tectonic pressure remains extremely active.
Sikkim, which still carries the memory of the destructive earthquake of 11 September 2011, has been experiencing recurring tremors over the years. With the new classification, the state is now officially recognised as being at higher seismic risk than previously estimated. The revised assessment also reveals that 61 per cent of India is now categorised under moderate to high earthquake hazard zones.
Scientists emphasise that the new zonation acknowledges the ongoing collision between the Indian and Eurasian tectonic plates, a geological force responsible for centuries of major earthquakes across the Himalayan belt.
Earlier maps divided the Northeast into Zones IV and V, but researchers argue this framework lacked precision. The new model addresses gaps in older assessments and focuses on long dormant fault systems in the central Himalayas, which, despite not rupturing for nearly two centuries, continue accumulating significant tectonic energy.
The updated assessment also cautions that future earthquakes could travel southwards, potentially affecting lower-lying regions such as the Brahmaputra Valley.
The revised mapping is based on advanced Probabilistic Seismic Hazard Assessment (PSHA) methods, which take into account likely maximum shaking intensity, active fault lines and the way seismic waves weaken across terrain. The Bureau of Indian Standards (BIS) has directed states to adopt the new 2025 map, replacing the earlier 2016 version, noting that three out of four Indians now live in seismically active areas.
Beyond mapping, the revised Earthquake Design Code introduces stricter safety requirements. Structural and non-structural elements, including lift systems, overhead tanks, façades and ceiling panels, must now be securely anchored if they exceed one per cent of a building’s weight.
The updated code also mandates that essential facilities such as hospitals, schools, bridges and pipelines must remain operational after a major seismic event. Experts believe this shift brings India closer to international seismic safety standards and provides a clearer roadmap for disaster resilience, especially for states like Sikkim where towns lie close to active fault lines.
India’s New Seismic Map Reveals High-Risk Earthquake Zones Across the Country
Gangtok, Dec 1 : A newly issued seismic zonation map has outlined varying levels of earthquake risk across India, placing several northern and northeastern states—including Jammu & Kashmir, Himachal Pradesh, Uttarakhand, Sikkim, Arunachal Pradesh, Assam, and the Andaman & Nicobar Islands—under the most severe earthquake risk category, Zone VI.
The map, which visually categorizes regions based on seismic vulnerability from Zone II (low risk) to Zone VI (very high risk), highlights the Himalayan belt as the most seismically active region. This zone stretches from the western borders of Jammu & Kashmir through Himachal Pradesh, Uttarakhand, Uttar Pradesh plains, Bihar, Nepal border regions, and further east across Sikkim, Assam, Meghalaya, Tripura, Nagaland, Manipur, Mizoram, and Arunachal Pradesh.
Major cities such as Srinagar, Shimla, Dehradun, Gangtok, Itanagar, Imphal, Aizawl, and Port Blair fall under the highest risk category.
Regions including Delhi, Patna, Ranchi, Kolkata, and parts of Gujarat such as Kachchh are placed under Zone V, indicating significant potential for damaging earthquakes. The Kachchh region of Gujarat—site of the devastating 2001 earthquake—continues to be a major seismic concern.
Much of central and southern India, including cities like Bengaluru, Hyderabad, Mumbai, and Chennai, falls into moderate-risk Zones III and IV. Meanwhile, southern regions like Kerala, Tamil Nadu, and the Lakshadweep Islands fall largely under the lower-risk Zone II category, although experts note that even low-risk zones are not completely immune to tremors.
Seismologists emphasize that India’s location along major tectonic boundaries—including the collision zone between the Indian and Eurasian plates—makes continuous mapping and preparedness essential. The updated seismic zoning will likely influence urban planning, infrastructure design, and disaster management policies nationwide.
Authorities and experts have urged states, especially those in Zones V and VI, to strengthen building codes, improve early warning systems, and raise public awareness to minimize potential loss of life and property in future earthquakes.
