Earthquakes don’t kill as much as poorly-constructed buildings do. This is the lesson the M7.9 (earthquake with an intensity of 7.9 on the Richter scale) Nepal temblor has flung yet again at the face of policy-makers.
Seismologists are of the view that the entire Himalayan region, including north and east India, is vulnerable to high-intensity earthquakes of a magnitude exceeding 8 on the Richter scale.
In the last 150 years or so, four such events have occurred: Shillong, 1897 (M8.7); Kangra, 1905 (M.8.0); Bihar-Nepal, 1934 (M8.3); and Assam-Tibet, 1950 (M 8.6).
Given this, the Nepal event was only waiting to happen, a top official at the National Disaster Management Agency said.
The Kashmir M7.6 earthquake (2004) had raised concerns that the contiguous region of the Himalayas to its east (covering India and Nepal) could well have been brought closer to a ‘large’ earthquake M7.8<M8, or perhaps a ‘great’ earthquake. Given the rise in population and the prevalence of poorly-assembled concrete structures, it is possible that future earthquakes will result in significant loss of life in the region, says Roger Bilham, renowned US-based seismologist and geologist.
“Your list of themes (of unsafe buildings and structures such as dams) is well posed,” Bilham had said in an e-mailed message to Business Line sometime ago.
“The true extent of vulnerable buildings is likely to be revealed only after earthquakes have damaged them.” It may be recalled that Bilham called these structures ‘weapons of mass destruction’ in the aftermath of the mega quake in Haiti a few years ago.
The population density at risk from an earthquake in the Himalayan region is large, and Bilham estimated in a paper titled ‘Seismic future of cities’ of a death toll of up to 1.5 lakh for a rupture length of the order of 150 km. Earthquake-resistant construction is absent here and despite the good intentions of the engineering community, there is no plan, nor much hope of fixing these buildings before their collapse.
The experts noted that low cumulative fatality count in India contrasts markedly with the seismic potential of the Himalayas and the subcontinent, and with the existence of large current populations.