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New warning on earthquake in Himalayan region

New warning on earthquake in Himalayan region
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First Published: Fri, Apr 29 2011. 12 36 AM IST
Updated: Fri, Apr 29 2011. 12 36 AM IST
Bangalore/New Delhi: North India could experience a powerful earthquake, it could happen sooner than expected and wreak more damage than previously estimated, according to the findings of a research study by scientists at Bangalore’s respected Indian Institute of Science (IISc).
India is nowhere close to being ready to deal with a powerful seismic shock, according to an official at the National Disaster Management Authority (NDMA).
The researchers analysed earthquakes over the years in the seismically-volatile northern Himalayan region. Their study will be published in next month’s issue of the Journal of Tectonophysics, a peer-reviewed journal.
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For at least three decades now, seismologists have been unanimous that a major quake (exceeding magnitude 8.2) is imminent somewhere between Bihar and Nepal, and Kangra (Himachal Pradesh), referred to as the central conflict zone, as well as around Delhi and Uttarkashi. The IISc scientists point out that those studies assume that the last major quake that rocked the region happened 500 years ago, whereas their calculations and on-site excavations suggest that such a quake happened 1,000 years ago.
Nirmal Chander Vij, former army chief and vice-chairman of NDMA, headed by Prime Minister Manmohan Singh, in a note published on the authority’s website earlier this month, said that India is “likely to take between 10 to 15 years to reach a minimum satisfactory level in terms of preparedness for earthquakes” and that “some very serious shortcomings persist in the preparedness levels because of our overall complacency towards this subject (preparedness for high-intensity earthquakes)”.
An 8.2 magnitude earthquake can release at least 30 times more energy than the one in Bhuj, Gujarat, in 2001, that killed at least 20,000. Pressure in the region’s crust is building up and could be released far more powerfully than previously imagined, the researchers warn.
“In our research work, where we have revisited the Himalayan region, an earthquake of larger magnitude happened 1,000 years ago and so the strain could be building up. So it (the quake, when it happens) has greater potential to be dangerous,” said Kusala Rajendran, one of the researchers of the study and faculty member at the Centre for Earth Sciences at IISc.
Previous studies, Rajendran said, used geological data based entirely on superficial global positioning system models, while their study that spanned 12 years included archaeological and geological data, such as the age of rocks and implements at different surfaces of the earth as well as ruptures and strains on old temples and buildings in the region.
“We also visited old structures to study the damage due to seismic activities,” said C.P. Rajendran, another IISc researcher involved in the study.
Earthquakes frequently alter the soil structure in a region and this can be used to determine the timing and frequency of quakes.
The 2,500km-long Himalayan mountain range, one of the active plate regions in the world, has experienced three great earthquakes during the past century.
Kusala Rajendran said that the 500–800km segment of the Himalayan arc between the rupture zones of the 1934 Bihar–Nepal and 1905 Kangra earthquakes, known as the central seismic gap has been “still” for a really long time. The plates in the zone are moving 5cm every year, which suggests a uniform movement and, therefore, the pressure ought to be released at periodic intervals, which is not happening, she added. This stretch in the central Himalayan region has not seen any earthquake, she said.
Vij’s note, published in the aftermath of the 11 March quake in Japan and the subsequent tsunami in Fukushima, said that the enforcement of and compliance with earthquake-resistant building codes for buildings and all other types of infrastructure is “woefully lacking because of vested interests” and needs to be improved substantially.
“There is a need to expeditiously carry out risk assessment and vulnerability analysis, strengthen multi-hazard preparedness, and prepare disaster management plans at national, state, district and block levels. This exercise was commenced some time back and needs to be finished urgently, and then rehearsed Army style,” said Vij.
Narender Kumar of the Wadia Institute of Himalayan Geology said that there was still considerable debate on the timing of such an earthquake. The paper by IISc scientists is “interesting”, he said, but a better understanding of when an earthquake could strike will come only by deeper monitoring of the earth’s crust with more sophisticated measurement systems. This process had begun seriously only since the early 2000s, he added.
Graphic by Sandeep Bhatnagar/Mint
bhargavi.k@livemint.com
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First Published: Fri, Apr 29 2011. 12 36 AM IST
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