Last week the world witnessed a spate of high-magnitude earthquakes in Japan, Ecuador and Myanmar. Roger Bilham, seismologist at the University of Colorado, who has studied the seismicity of the Himalayan belt and is a world-renowned expert in the field, has predicted that four great earthquakes are expected to hit North India, each of magnitude 8.0 or more. Disaster management experts from the ministry of home affairs also echoed similar views. The rupture of the Himalayan fault has begun and we will be seeing periodic earthquakes for the next 20-25 years until all accumulated strains are dissipated.
In India, the Supreme Court has passed explicit instructions on earthquake safety through a public interest litigation. Our country has the maximum number of quake-unsafe buildings in the world.
The Supreme Court order on earthquake safety vide its judgment dated December 5, 2014, on a public interest litigation states that the National Disaster Management Authority (NDMA) should undertake a public awareness campaign on a national basis through print and electronic media. It states that all buildings housing more than 100 persons and all multi-storey buildings with more than five storeys, both new and old should have an engraved metal plate mentioning the earthquake-resistant category of the building. Advertisements of all realty projects should carry the earthquake-resistant category.
IIT-Roorkee recently reported on the vulnerability and danger of ‘flat slab’ buildings collapsing in the event of an earthquake. Construction of ‘flat-slab’ buildings is not allowed in seismic zones 3, 4 and 5 but these continue to exist, most of them in the high occupancy category.
Advice for homebuyers
1. When buying a house, you should not shy away from asking specific questions on earthquake safety from the seller. Written records of the questionnaire sent and responses received should be saved. This will give legal tooth, if anything were to go wrong in future
2. Earthquake resistant buildings are of 4 types, Type A – operational, Type B – immediate occupancy, Type C – life safety and Type D – collapse prevention. Type A is the best and Type D the lowest. It is important for occupants of buildings to know which category their building falls in
3. Nearly 100% of the buildings in India are being designed and constructed under Category D or Collapse Prevention standard. These buildings will get severely damaged and will not be habitable or economically repairable after an earthquake.
4. Home buyers should not get confused with statements like the building has been designed to Zone 5 or Zone 4 standards. Zones depict the seismic hazard and earthquake resistance category depicts the seismic performance of a building
5. A Type B building will typically cost approximately `350 per sq ft more than a Type D building. Type B building will have minimal structural damage and will be structurally safe to occupy and use even after a major earthquake.
Credits Hindustan Times