Most structures built more than a decade ago are unlikely to qualify for existing seismic requirements of the National Building Code, upgraded based on the frequency of earthquakes. Though the city falls under seismic zone III and is categorised a moderate risk zone, structural experts underscore the need for scaling up buildings to make them earthquake resistant so that they are safe for occupants in the event of a natural calamity.
Experts say the magnitude of impact of the moderate earthquake on buildings in the city would have been higher had the epicentre been close to its coast. Chennai-based structural engineer T M Ramakrishnan, who has designed buildings across the country as per seismic zones, said older buildings would have suffered damages in such a situation.
“People look for water sources, public transport and location while choosing a house, but there is a lack of awareness on seismic parameters for homes. In fact, buildings constructed more than 10 years ago must be overhauled to comply with seismic code and designs,” he said.
Retrofitting has become common in cities such as Delhi and Mumbai, he added.
The Tamil Nadu Combined Development and Building Rules lays down norms for adhering to the National Building Code for constructions ranging from single storey homes to multi storey structures. Kumar, former chairman of Confederation of Real Estate Developers’ Association of India (CREDAI), Tamil Nadu chapter, said developers had moved to Mivan technology to make structures quake resistant.