India’s seismic risk assessment has undergone a major revision with the Bureau of Indian Standards (BIS) unveiling a new zonation map. The map has placed the entire Himalayan arc in the highest-risk Zone VI for the first time. This marks one of the most significant shifts in seismic hazard assessment in decade. With 61% of the country now classified under moderate to high hazard zones, the update calls for urgent need for stricter building codes and improved attention to both structural and non-structural safety measures to reduce casualties during earthquakes in future.
What does new the marking mean?
The changes that have been noticed in the new zonation map are the marking of highest- risk Zone VI, increased hazard zones, and revised building code. Zone VI in the new BIS seismic zonation map refers to the highest-risk seismic zone, meaning the areas in this category are expected to experience the strongest ground shaking and are most prone to major, potentially devastating earthquakes. This also highlights that earthquake preparedness is most urgent in these regions.
These states face highest risk
According to the BIS, the entire Himalayan arc, from Arunachal Pradesh to Kashmir, has been placed in the new highest-risk category. The map also reflects Indian-Eurasian plate collision, building stress beneath states like Uttarakhand, Himachal Pradesh, and some parts of Uttar Pradesh, which are densely populated.
Earlier, the Himalayan belt was split between Zones IV and V even though the entire region faced the same tectonic dangers. The old maps did not fully account for the high risk from long-unruptured faults particularly in the central Himalayas, where a major quake has not occurred for almost 200 years. The belt falls in India’s highest seismic risk zone as it is one of the most active tectonic collision boundaries on Earth. Moreover, the Indian Plate is continuously pushing northward into the Eurasian Plate at about five centimetres per year, driving the Himalayas upward.
BIS calls for immediate adoption of updated 2025 seismic codes
BIS emphasised that the new map gives a clearer picture of how strong ground shaking could be during future earthquakes. It has urged that all new buildings and infrastructure must use the 2025 map instead of the 2016 version. This has been advised so that safety standards match the latest understanding of seismic risk. This update is especially important because nearly three-fourths of India’s population lives in earthquake-prone areas, and the share of land in moderate to high hazard zones has risen from 59% to 61%.
Some of the stricter safety requirements stated by BIS are:
New buildings and infrastructure should follow 2025 code instead of the 2016 version.
Heavy non-structural components (over 1% of building weight) must be securely anchored to prevent internal collapses.
Critical infrastructure like hospitals and schools must be designed to remain operational after a major earthquake.
The new code also includes an “exposure window” that considers population density and socioeconomic vulnerability to assess overall impact more accurately.
