Seismic activity zones

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Bureau of Indian Standards , based on the past seismic history, grouped the country into four seismic zones, viz. Zone-II, -III, -IV and –V. Of these, Zone V is the most seismically active region, while zone II is the least. The Modified Mercalli (MM) intensity, which measures the impact of the earthquakes on the surface of the earth, broadly associated with various zones, is as follows:

                       Seismic Zone                                                   Intensity on MM scale

II  (Low intensity zone)                                                     VI (or less)

III (Moderate intensity zone)                                           VII

IV (Severe intensity zone)                                                 VIII

V  (Very severe intensity zone)                                          IX (and above)

  • Twenty-nine Indian cities and towns, including Delhi and capitals of nine states, fall under “severe” to “very severe” seismic zones, according to the National Centre for Seismology (NCS).
  • A majority of these places are in the Himalayas, one of the most seismically active regions in the world.
  • Delhi, Patna (Bihar), Srinagar (Jammu and Kashmir), Kohima (Nagaland), Puducherry, Guwahati (Assam), Gangtok (Sikkim), Shimla (Himachal Pradesh), Dehradun (Uttarakhand), Imphal (Manipur) and Chandigarh fall under seismic zones IV and V.
  • The Bureau of Indian Standards (BIS) has classified different regions in the country into zones II to V, taking into consideration earthquake records, tectonic activities and damage caused, the director of the NCS, Vineet Gauhlat, said.
  • Bureau of Indian Standards, based on the past seismic history, grouped the country into four seismic zones, viz. Zone-II, -III, -IV and –V. Of these, Zone V is the most seismically active region, while zone II is the least. The Modified Mercalli (MM) intensity, which measures the impact of the earthquakes on the surface of the earth, broadly associated with various zones, is as follows:Gk bit – Seismic Zone Intensity on MM scale:
ð Seismic Zone ð Intensity on MMI scale ð % of total area
ð II (Low intensity zone) ð VI (or less) ð 43%
ð III (Moderate intensity zone) ð VII ð 27%
ð IV (Severe intensity zone) ð VIII ð 18%
ð V (Very severe intensity zone) ð IX (and above) ð 12%