Delhi and NCR may have escaped the wrath of Saturday’s earthquake but it is virtually sitting on a faultline. A major earthquake measuring six or more on the Richter scale may spell disaster in the city, which is seeing unbridled construction for the past few years.
While on one side there are uncountable high-rise commercial and residential buildings that have turned Delhi and satellite towns of Gurgaon, Noida, Faridabad, Ghaziabad, and Sonepat – which fall in seismic zone 4 - into cities of concrete, the unchecked growth of unauthorised colonies have compounded the problem.
Experts believe there could be serious issues in structural designs and implementation of building codes making the high-rises susceptible to strong vibrations. The concrete structures that have come up in unauthorised colonies do not meet even the basic requirements of building codes.
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The 2010 Lalitha Park building collapse, which left 71 dead and more than 200 injured, is a case in point. The five-floor residential building, which housed more than 200 tenants and had several sweatshops running on its premises, had flouted all rules of building construction.
“Such structures in unauthorised colonies and lal dora area are quite vulnerable. A large number of such structures have come up along the banks of the Yamuna where the severity of earthquake increases due to loose soil. While the new government in Delhi should look at this issue carefully, the civic agencies are also required to look at the old structures in the Walled City, which require strengthening,” said RC Kehar, former chairman-cum-managing director, National Building Construction Corporation.
Delhi currently has close to 2,000 unauthorised colonies, which are in different stages of regularisation. Close to 50 lakh people live in these colonies.
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While there are strict building codes for high rises in Delhi and NCR, experts agree that many structures still lack structural safety. Illegal changes in shape and design of the structure during the construction stage make these buildings vulnerable.
“There are enough codes and practices published by the Bureau of Indian Standard BIS on how to design earthquake resistant structures. But implementation is an issue. It is the job of structural engineers to give proper shape and form to a building, which has strong vertical load bearing capacity as well as face the horizontal forces in times of earthquake. But structural engineers are rarely involved in overall design, planning and construction of the building,” said Mahesh Tandon, president, Indian Associations of Structural Engineers.
Dikshu Kukreja, managing director of prominent architectural firm CP Kukreja and Associates also concurs on this. “The concept of getting structural stability certificate came up only a few years ago. Numerous changes are made in the structural design during the construction,” Mr. Kukreja said.