Nation rests on very shaky ground
About 80 percent of India’s population resides in regions that are vulnerable to earthquakes of moderate to extreme intensity. If an earthquake of a magnitude as strong as the Nepal earthquake occurs in India, will our buildings survive?
Last year, a report by the National Disaster Management Authority had pointed out that 95 percent of deaths during past earthquakes in India have mainly been due to the collapse of poorly engineered buildings and structures. This calls for a reflection on the nature of the country’s buildings and construction practice, and whether they can survive earthquakes with little or no damage.
India has commendably improved its post-disaster response and management capacity, as was observed in the rescue and relief mission in Nepal. But it is yet to strengthen its infrastructure to withstand earthquakes. “Pre-disaster preparedness is a big area for intervention. We are systemically building our capacity for this, but there is still a lot to achieve,” says Santosh Kumar, executive director, National Institute of Disaster Management (NIDM), New Delhi.
Codes to prevent collapse
In 2006, the government-appointed Tejinder Khanna Committee found that 70-80 percent of buildings in Delhi violate building and development control regulations. Other cities are not better off. “Just a fraction of cities and towns in India take into account National Building Code (NBC) and other building regulations,” says Anup Karanth, public safety and risk management specialist in Delhi.
Buildings need to be designed with safety features to withstand earthquakes. The Bureau of Indian Standards (BIS) prescribes seismic codes that help engineer such buildings. The popular perception is that a skyscraper would be more dangerous than a shorter building during an earthquake. But both are equally vulnerable if not engineered properly. Ground shaking is a natural phenomenon, and buildings are expected to be engineered to withstand this. Taller structures are more flexible. They absorb earthquake vibrations by distributing them along their height. This lowers but does not eliminate, the impact of the quake. In case of shorter buildings, the force of the earthquake gets concentrated due to lack of height to dissipate the energy, often resulting in collapse.
“Codes have been frequently revised and cover all kinds of construction technology and building typology,” says Sanjay Pant, director of civil engineering at BIS.“NBC has even laid out detailed administrative guidelines for implementing these codes,” he adds.
The ground below a structure is as important as the design and engineering of the building. Bedrock is better at absorbing shockwaves than sandy soils or landfills. So buildings on solid rock will be much less affected than those built on softer soil or reclaimed land. Further, if <g data-gr-id="129">softer</g> soil has water, it will be prone to liquefaction—a phenomenon where the ground becomes a little like quicksand—during an earthquake. Buildings on top of liquefied soil usually sink and often topple. Development control regulations formulated by the government address these vulnerability issues, but these regulations are not strictly adhered to in India.
The urban local bodies are responsible for checking compliance to NBC and development control regulations at multiple stages—first at the design stage of the building, then during its construction and finally at the time of completion before granting occupancy certificate. But the guidelines are blatantly violated, either because the urban local bodies are understaffed or underqualified. “The building’s structural design is hardly checked by government authorities, especially in the case of residential units, while the construction, too, happens more or less unchecked. Such loopholes make way for deficiencies, such as <g data-gr-id="125">poor</g> strength of concrete, use of improper material and improper method of construction,” Karanth says.
While it is the responsibility of structural engineers to check building designs at the municipal level, their availability is a challenge as most of them are absorbed in medium and large construction firms. “Civil engineering is a stepping stone to specialisation in structural engineering, but seismic designs are hardly covered in the civil engineering curriculum,” says Mahesh Tandon, president, Indian Association of Structural Engineers.
The seriousness of the problem was demonstrated during a building collapse in November 2010 at Lalita Park in east Delhi’s Lakshmi Nagar, in which more than 60 people died. Following this tragedy, the Delhi government issued an order in April 2011 making it mandatory for all builders to submit sanctioned building plans along with structural safety certificates for their new buildings. Within days, the number of applications for property registration saw a drastic fall. Ten days later, the Municipal Corporation of Delhi informed the government that it did not have enough structural engineers to issue the certificates. The order was revoked.
Accountability is another problem. “Today structural safety certificates are bought and sold and there is no cross-checking of their authenticity. There is no statutory body in place to regulate engineering practice,” Tandon adds. Such administrative loopholes in the approval and construction of buildings can spell disaster whenever the country is rocked by a major earthquake. So, what is the way ahead?
Retrofitting is the only solution
Seismic codes have been in place since 1962. But the collapse of more than 200,000 houses in the Bhuj earthquake made the government realise that the codes were lenient. BIS revised them in 2002 to meet stronger seismic threats. This revision implied that India’s buildings constructed before 2002 are not strong enough to withstand earthquakes and require retrofitting.
NIDM is preparing a possible retrofitting roadmap for India. “The main challenge is the time needed for retrofitting. Providing adequate housing to people while their buildings undergo retrofitting is challenging,” Kumar says. <g data-gr-id="113">Cost</g> of retrofitting can also be very high. Pant adds that it is often cheaper to demolish a complete structure and rebuild it to withstand earthquakes than undertake retrofitting.
But such expenditure is non-negotiable as the safety of occupants is at stake. Take New Zealand, for example. After a 6.3 magnitude earthquake killed 185 people in Christchurch in February 2011, buildings are being retrofitted to reduce vulnerability. New Zealand also mandates unsafe buildings to display warning notice. A similar order was issued by the Supreme Court of India in December 2014 seeking all buildings that house more than 100 people to display their earthquake resistance status. But there is no clarity on who is responsible for its implementation.
In the absence of administrative action, public participation becomes crucial. But how would a resident know if his or her building needs retrofitting? “Any building built or designed before 2002 and/or located on reclaimed land or floodplains should consult a registered structural engineer or an experienced civil engineer,” Tandon says.
People can also learn some basic visual screening to determine seismic defects. There are simple things that people can check for. In case of masonry structures, the buildings must have continuous concrete bands connecting all doors and windows at lintel and sill levels. Also, the total width of all the openings in any wall must not be more than half the total length of the wall. In case of reinforced concrete structures that are multi-storey, presence of soft storeys—any floor with only pillars and no walls—is dangerous. People should ensure that extensions to buildings are done with proper engineering inputs.
Long road to safety
Another challenge is that poor people’s homes are not included in the government’s plan of action for disaster preparedness. Currently, there seems to be no strategy in place to deal with the aftermath of a disastrous earthquake. “Since implementation of seismic codes is difficult to monitor, awareness campaigns should be the long-term approach. It should be coupled with the certification of building artisans and training and upgradation of their skills and knowledge,” says Rajendra Desai, managing trustee and joint director, National Centre for People’s Action in Disaster Preparedness, an Ahmedabad-based non-profit.
Karanth maintains that important institutions—hospitals, police stations, fire stations, sewage and water treatment plants, community halls, schools, libraries, government offices and utility companies dealing with electricity, power and gas—should be immediately assessed and retrofitted for seismic safety on a priority basis.
“Rapid Visual Screening of elevated urban infrastructure like bridges, flyovers and metro lines should be undertaken every six months and a detailed inspection carried out every three to five years,” Tandon suggests.
How an earthquake will affect a city has a lot to do with how its citizens and governments have engineered buildings and civic infrastructure. Lessons can be drawn from cities like Tokyo and San Francisco, which frequently battle shaking grounds with their quake-resilient engineering.
Administrative intervention could not prevent 450,000 houses from collapsing during the Kashmir earthquake in 2005. The numbers can reach millions if an earthquake hits a more densely populated region such as the seismically vulnerable Indo-Gangetic plains. The government should put in place a mission framework which can fast track and absorb the massive cost required for improving the seismic performance of our structures. Earthquakes cannot be stopped, but casualties and economic damage can be averted by acting wisely, and now.