On the basis of the intensities or the destructiveness of the earthquakes a map of India has been published by the Meteorological Department in collaboration of the Indian Standard Institution. The map shows the five seismic zones based on modified Mercalli Scale.
Zone I - Intensity V or below (instrumental, feeble, slight, moderate rather strong)
Zone II - Intensity VI (Strong)
Zone III - Intensity VII (Very Strong)
Zone IV - Intensity VIII (destructive) Zone
V - Intensity more than VIII (disastrous, catastrophic)
Comprises some areas of Punjab and Haryana, plains of Uttar Pradesh, Coastal plains of Maharashtra and Kerala, certain parts of the plains of Bihar and West Bengal, certain areas in Rajasthan and major part of Gujarat except Kutch.
Includes southern Punjab and Haryana, certain parts of the plains of Uttar Pradesh, eastern Rajasthan, coastal areas of Orissa and Tamilnadu. This is the low damage risk zone.
Covers southern and Southeastern parts of Rajasthan, larger parts of Madhya Pradesh, Maharashtra, Karnataka, Jharkhand and northern and northwestern part of Orissa.
Represents areas where there is high damage risk by destructive earthquakes. This zone comprises the State of Jarnmu and Kashmir, Himachal Pradesh, northern part of Punjab and Haryana, Delhi, eastern Uttar Pradesh, tarai and bhabar regions, the Himalayan areas of Uttaranchal, Bihar and Sikkim.
Represents areas of the most destructive and catastrophic earthquakes where there is extremely high damage risk. The following areas fall into this zone: certain parts of Jammu and Kashmir, parts of Himachal Pradesh, Uttaranchal, Monghyr and Darbhanga districts of Bihar, northern part of India and Kutch region of Gujarat.
This map gives the most generalised picture about the intensities of earthquakes occurring in different zones. There are, it is true, some very strong exceptions. Calcutta earthquake of 1737, which killed about 300,000 people offers as typical example.
As shown in the map of the earthquake prone zones of India, Calcutta is located in a zone where normally there is little chance of very destructive earthquakes.