Two Third of Country’s Population and Housing Located within Seismic Zones
Shri Vilasrao Deshmukh said that twenty seven cities in India have a population of one million or more and around 25% of the total urban population of the country lives in these cities. Addressing a workshop on “Current Scenario of Seismic Microzonation in India” here today, Shri Deshmukh informed, “This is compounded by the fact that while geographically, 57% of the Indian landmass is under Seismic Zones III, IV and V, about 2/3rd of the population and housing are located within these zones. Over the years, most of the urban complexes in India have undergone a phenomenal growth for various socioeconomic reasons. Thus, the vulnerability of our cities exposure to different hazards has also increased considerably. This necessitated a proper hazard assessment and management framework.”
Natural disasters are location depending in the sense that a hazard is aggravated by the geology, topography and land cover at the location of the hazard. Most casualties during earthquakes are caused by the collapse of structures, both engineered and non-engineered. The last few decades have seen a phenomenal growth of infrastructure including high-rise buildings, water and sewage works and transportation networks, in urban areas. The Minister said that all these efforts towards seismic microzonation of mega centres must be incorporated in the master plan of the Ministry of Urban Development and State Governments as well as panchayat and village levels. It will also bring awareness amongst the public for mitigating the earthquake risk in future
Over the years and particularly during the last two decades, the study of earthquake has received prime attention of the Government of India. The loss of life and the damages inflicted by the recent significant earthquakes and the Tsunamis have shifted our focus from a culture of reaction to practices and norms of prevention and preparedness. There is no scientific technique to prevent or forewarned earthquake. Under these circumstances, it is pragmatic to formulate strategies to minimize the primary and secondary effects arising out of large earthquakes. This necessitates development of tools for hazard assessment and subsequently mapping the parameters necessary for improvement of long-term planning of the cities. This will ultimately bring improvement of long-term planning of the cities. The accurate knowledge of subsoil structures and probable complex source mechanisms in used to study the local site effects in large urban areas and mega cities.
Talking about microzonation Shri Deshmukh said, “ This is similar to the macro level hazard evaluation. It also requires more rigorous inputs about the site specific geological geophysical, geotechnical, seismotectonic, ground response to earthquake motions. And their effects on the safety of the constructions, taking into consideration the design aspects of buildings, ground conditions. This would enhance the earthquake effects and safe construction practices to avoid the losses from the future earthquakes. In India seismic hazard and risk assessment studies of urban complexes at micro level are more than a decade old. During this period, different institutions and individuals have carried out some basic work and accomplished useful results. It is contemplated that seismic microzonation and risk assessment of individual urban centres falling in seismic zones V, IV and III would be completed in the near future.”
He said that if the principles of microzonation are judiciously applied, they could be useful in establishing criteria for land use planning and a strategy for the formulation of a systematic and informed decision making process. Although the effort and work involved in microzonation of urban centers is huge, successful attempts have been made for a few selected cities in India.
The Minister also released “Seismic Microzonation Handbook” and “ Seismic Microzonation Manual”. He said this is timely and will prove immensely useful to the Geo-Scientific ,geo-technical and Earthquake Engineering community in the country.
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