Northeast India falls under which of the following Seismic Zones?

The Bureau of Indian Standards (BIS), under IS 1893, classifies India into seismic zones ranked by earthquake hazard — from Zone II (the lowest hazard in the current scheme) to Zone V (the highest hazard), with Zone III and Zone IV as intermediate bands. An earlier five-zone version also had a Zone I, but that category was folded into Zone II when the standard was revised in 2002, leaving four zones (II-V) in the current classification.

Northeast India sits on the Himalayan-Burmese arc, where the Indian plate converges with and subducts under the Burmese microplate — one of the most tectonically active margins in the world, with a recorded history of great earthquakes such as the 1897 Shillong (magnitude about 8.1) and 1950 Assam-Tibet (magnitude about 8.6) events. Under IS 1893:2016, this entire tectonic setting places all seven Northeastern states — Assam, Arunachal Pradesh, Meghalaya, Manipur, Mizoram, Nagaland, and Tripura — in Zone V, the country's highest seismic-hazard classification.

• Zone I: belonged to the earlier five-zone scheme and was merged into Zone II in the 2002 revision; the present classification has no separate Zone I.

• Zone III: the moderate-hazard band, applied to large interior and southern tracts of the country that see only occasional, low-to-moderate intensity earthquakes.

• Zone IV: the high-hazard band, applied to tracts such as the Delhi-NCR belt, the Kashmir Valley, Sikkim, and parts of northern Bihar and coastal Maharashtra.

Zone V is therefore the correct classification for the seven Northeastern states.