Seismic Mapping : Vulnerability of important cities/towns of India Under threat of Earth Quakes

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-By Jay Singh Rawat

Minister of State (I/C) for Science & Technology and Earth Sciences, Shri Jitendra Singh informed the Lok Sabha  on 30 July 2021  in a written reply that, considering the recorded history of earthquakes in the country, a total of ~59% of the land mass of India (covering all states of India) is prone to earthquakes of different intensities. As per the seismic zoning map of the country, the total area is classified into four seismic zones. Zone V is seismically the most active region, while zone II is the least. Approximately, ~ 11% area of the country falls in zone V, ~18% in zone IV, ~ 30% in zone III and remaining in zone II.

 

List of important cities/towns of India that fall under the high seismic zones of IV
and V, State/UT-wise, are given in table below:

 

City/Town State/UT Zone City/Town State/UT Zone
Almora Uttrakhand IV Jorhat Assam V
Ambala Haryana IV Jalpaiguri West Bengal IV
Amritsar Punjab IV Kooch Bihar West Bengal IV
Baharich Utter Pradesh IV Kohima Nagaland V
Barauni Bihar IV Kolkata West Bengal IV
Bhuj Gujarat V Ludhiana Punjab IV
Bulandshahr Uttar Pradesh IV Mandi Himanchal Pradesh V
Chandigarh Chandigarh IV Monghyr Bihar IV
Darbhanga Bihar V Moradabad Uttar Pradesh IV
Darjeeling West Bengal IV Nainital Uttrakhand IV
Dehradun Uttrakhand IV Patna Bihar IV
Deoria Uttar Pradesh IV Parganas West Bengal IV
Delhi Delhi IV Pilibhit Uttar Pradesh IV
Dinajpur West Bengal IV PortBlair Andaman & Nicobar  V
Ghaziabad Uttar Pradesh IV Roorkee Uttrakhand IV
Gangtok Sikkim IV Sadiya Assam V
Guwahati Assam V Simla Himanchal Pradesh IV
Gorakhpur Uttar Pradesh IV Srinagar Jammu & Kashmir V
Imphal Manipur V Tezpur Assam V

 

The National Centre for Seismology under the Ministry of Earth Sciences is the nodal agency of the Government of India (GoI), for monitoring earthquakes in and around the country. For this purpose, NCS maintains a National Seismological Network (NSN) consisting of 115 observatories spread across the country. The information of earthquakes reported by NCS is being disseminated to the concerned central and state disaster authorities in the least possible time to initiate adequate mitigation measures.

 

Secondly, the Seismic Microzonation of cities in India having a population of 5 Lakh and above is also considered. The purpose is to generate inputs for constructing earthquake risk resilient buildings/structures to reduce and mitigate the impacts of earthquake shaking and for minimizing the damages to structures and loss of lives for safer urban planning.

Additionally, National Disaster Management Authority (NDMA) of Indiais engaged with conducting regular awareness campaigns every year through print, electronic as well as social media from time to time to sensitize programs on prevention and preparedness for building safety from earthquakes.

Besides, the Government of India is poised to follow guidelines by the Bureau of Indian Standards (BIS), Building Materials & Technology Promotion Council (BMTPC), and Housing and Urban Development Corporation (HUDCO) etc. for design and construction of earthquake risk-resistant structures to minimize the loss of life and damage to property caused by earthquakes. These guidelines are in wide circulation amongst the public and the administrative authorities responsible for the design and construction of earthquake-resistant structures in earthquake-prone areas.

The seismic Zonation map of the country (state-wise) given by the Bureau of Indian Standards (BIS) has categorised into several seismic zones (Zone II to Zone V) with variability of peak ground acceleration (PGA) (0.16g to > 0.36g) with of 10% of exceedance in PGA in 50-years as shown in the figure below. According to this map the state of West Bengal falls under Zone IV, III and II. A larger portion of West Bengal state lies in Zone III. The state of Uttar-Pradesh, the state lies in Zone IV, III, and II.

 

 

 

The seismic zones of the entire country including West Bengal are classified based upon the empirical seismic attenuation law with respect to the maximum credible earthquake source zone located at the vicinity of the area under study, which has further corroborated with historical seismicity and ground motions of the earthquakes observed in various parts of the country in past. This data was analysed by Bureau of Indian Standards to prepare a Probabilistic Seismic Hazard Zonation Map of India.

 

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