Are Highrises In India Earthquake Proof?

India's most famous building, the Taj Mahal, is one of the safest buildings in times of earthquake. Are other buildings in your town just as safe? Probably not. In the aftermath of Nepal earthquake in April 2015, a lot of people are pondering over the same question. There are already towers which are 40 floors high in Mumbai, and there are talks about erecting 60-floor towers and even 100-floor structures.

Codes for earthquake

Building codes have a number of safety norms in place which ensure that skyscrapers are safe in times of earthquakes and other disasters. Reputed builders of upcoming properties in Mumbai and Delhi and tall buildings follow these norms and even advertise them as USPs. This is true with most new buildings which are less than five years old and which have taken safety standards very seriously. The building code, which was revised as recently as 2009, has fresh safety parameters listed out.

How can they be safe?

The choice of the ground of a building has a huge say in making it earthquake resistant. The best way would be to ensure that such buildings are built on bedrock. Those which are built on soft or filled-in soil rank much lower in safety.

There are many techniques that can make a skyscraper earthquake resistant. One of them is 'base isolation'. A number of skyscrapers designed in the last few decades are built on a base of ball bearings, springs and padded cylinders. They absorb shocks as the ground under them shakes. These buildings sway for a few feet during a tremor. Such buildings have to be spaced out so that they do not swing onto other structures.

Yet another technique is to build 'dampers' in a building in any residential project in India that reduces the sway of the building. It was used in Taipei 101 where a giant pendulum spanning four floors was built, making it the world's largest damper. 

New versus old buildings

Making a building earthquake resistant will increase its cost by around 20%. A builder can make up for this cost by getting a better premium for its insurance. So, a lot of new buildings follow the codes for making them safer. 

The worry, however, is with the highrises which were built around 10 years back or more. Older buildings continue to remain unsafe and it would require intervention of civic bodies and local governments. Experts say that older buildings can also be made earthquake-resistant by retrofitting them by strengthening the base of the structures. This would cost around 20% of the total cost of the structure. Unlike in new buildings, the cost is cannot be easily recoverable from the owners. Most of the building societies show apathy to the extra investment that they have to fork out. Also, the government finds it difficult to test older buildings.

Government push for safety

A few municipalities are encouraging the people and the societies to make their buildings safe. For example, the Delhi government is all set to publish a list of structural engineers registered with various civic authorities. A society in residential projects in Delhi can always consult these professionals to check the building for its ability to resist an earthquake. They can also suggest the kind of retrofitting required to make it safer.

Most unsafe cities?

Many experts across the country are, however, worried about other cities as well. While Mumbai and Delhi has the most highrises which can cause damage to their residents and neighborhood alike during disaster, other cities too have fewer enforcements and awareness to this extent. Bihar is in the high-seismic zone and is also witnessing rapid real estate development, including residential projects in Patna. Orissa, too, has shown a lot of apathy towards safety of buildings. Gujarat is still unsafe even after the devastating 2001 earthquake. Mumbai is the worst of the lot. It has a number of buildings which are nearly a hundred years old and score very low on all safety parameters.

(The writer has been working as a business journalist for the last nine years, and has covered beats across banking, pharma, healthcare, telecom, technology, power, infrastructure, shipping and commodities)