What if the 7.9-magnitude Nepal earthquake had its epicentre in Delhi?
After the 7.9-magnitude earthquake ravaged Nepal’s Kathmandu Valley, many in India who were jolted by the tremors wondered what would have happened if the epicentre had been closer to home. Experts have already said that if the epicentre of Saturday's temblor had been in or near Delhi, about half of the metropolis of nearly 17 million people would have been wiped out.delhi Updated: Apr 27, 2015 16:24 IST
After the 7.9-magnitude earthquake ravaged Nepal’s Kathmandu Valley, many in India who were jolted by the tremors wondered what would have happened if the epicentre had been closer to home.
Experts have already said that if the epicentre of Saturday's temblor had been in or near Delhi, about half of the metropolis of nearly 17 million people would have been wiped out of earth.
DK Paul, professor emeritus at IIT Roorkee’s earthquake engineering department and part of a team that carried out a microzonation study of Delhi in 2007, told HT that devastation in the city would be greater because of its high seismicity (it falls in the high-risk Seismic Zone IV) and unplanned growth that flouts structural safety norms.
The microzonation study had revealed that private buildings in Delhi, especially those in the trans-Yamuna and Walled City areas, would suffer maximum damage if an earthquake of 7-magnitude or higher strikes the capital.
“An earthquake of 7 and above magnitude with its epicentre in and around Delhi would cause havoc in the capital mainly because buildings here lack seismic resistant measures. Not only is Delhi densely populated but there is complete lack of enforcement by authorities to ensure that building codes and structural safety norms are followed,” said Paul.
Experts have said that very few buildings across India meet standards prescribed in the Indian Standard Criteria for Earthquake Resistant Design, last revised in 2005.
"These (standards) are not enforced, so almost no one knows such earthquake-resistant standards and guidelines for home-owners exist," said a report by IndiaSpend.
A study done by IndiaSpend showed that the Delhi Metro is one of the few Indian structures built to withstand a quake.
According to norms, municipalities have to give the go-ahead for construction only if buildings comply with the Indian Design Code, which was revised in 2002 and lays down criteria for earthquake-resistant design.
“But the problem is we do not have a regulatory framework to ensure compliance of the building code, resulting in people getting clearance even if their building does not have retrofitting or other seismic resistant measures,” Paul said.
The intensity of Saturday’s quake in Delhi was about 5, which experts said was not very potentially damaging.
“It is not earthquakes that kill, it is the buildings. It depends on how resilient a building is...on structural design. If a building is structurally sound, nothing would happen,” said India Meteorological Department chief Laxman Singh Rathore.
Experts said Delhi also faces different kind of risks when compared to other cities in zones with high seismicity.
“The devastation will differ in different locations. For instance, areas in east Delhi along the Yamuna that are in the liquefaction zone would suffer the maximum damage on account of dense, unplanned growth,” said Santosh Kumar, director of the SAARC Disaster Management Centre.
“Rampant unauthorised construction has meant that building bylaws have not been adhered to, even basic soil testing was not carried out before starting construction.”
Even in the case of Nepal, researchers had warned that destruction would be massive because of the rapid and unplanned urbanisation of Kathmandu.
A report published earlier this month by GeoHazards International, a US-based nonprofit that helps poor nations in tackling disasters, warned that Kathmandu ran the risk of massive destruction whenever a calamity struck because of its annual population growth rate of 6.5% and one of the highest urban densities in the world.
The report said the Nepal government did not control the valley’s rapid development and there were no building codes in place. “…nearly all construction took place without consideration of seismic force concerns,” it said.