The Hindu : National : A great earthquake may be `overdue' in the Himalayas

Online edition of India's National Newspaper
Tuesday, Apr 05, 2005

National

National

A great earthquake may be `overdue' in the Himalayas

By N. Gopal Raj

THIRUVANANTHAPURAM, APRIL 4. A 100 years ago today, a powerful earthquake, estimated to have had a magnitude of 7.8, with its epicentre near Kangra in Himachal Pradesh claimed over 20,000 lives and caused extensive damage. Experts worry that some parts of the Himalayas could be ready for another dangerous quake.

Roger Bilham of the University of Colorado in the United States has long argued that a great earthquake is "overdue" in the Himalayas. There were a dozen examples of regions across the Himalayas that could rupture and produce an earthquake with a magnitude over 8, Dr. Bilham said in a talk at a conference to mark the centenary of the Kangra earthquake. "Potentially the most dangerous of these is the so-called Central Himalayan Gap whose rupture in 1505 may have occurred as a 600-km-long rupture, similar to the tsunamigenic initial phase of the 2004 Sumatra earthquake," he said.

In a commentary published recently in the scientific journal Nature, Kerry Sieh of the California Institute of Technology spoke of the hazards posed by big faults north of the rupture that produced last December's earthquake. The northern extension of the 2004 rupture continued for another 1,000 km, up the west coast of Myanmar, well past Bangladesh to the eastern end of the Himalayas. Moreover, long sections of the enormous thrust fault along which India was diving down beneath the Himalayas had not failed for centuries and were only one to three fault-lengths away from the 2004 rupture, he observed.

With greater population density, up to 300,000 lives could be lost if an earthquake the size of the 1905 Kangra earthquake was to occur today, warned Harsh K. Gupta, currently Secretary to the Department of Ocean Development, in the December 2000 issue of EQ News, a newsletter published by the Department of Science and Technology.

Strains at weak zones

There are also earthquake threats away from the boundaries where the Indian plate is colliding with the Eurasian plate. Strains can accumulate at weak zones within the Indian plate, says C.P. Rajendran of the Centre for Earth Science Studies here. The earthquake at Bhuj in Gujarat on Republic Day in 2001 is an example of such an earthquake. There are faults around the Rann of Kutch and in Assam that could produce large quakes, he told The Hindu .

As earthquakes cannot be predicted, reducing the risk of buildings and other constructions such as dams and bridges collapsing becomes critical. India must move to a system that estimates the probability of varying levels of ground movement occurring, R. N. Iyengar of the Indian Institute of Science, who was director of the Central Building Research Institute at Roorkee, said. An important building, such as a hospital, could then be designed to withstand a more powerful earthquake that may happen only infrequently. In vulnerable cites such as Delhi, Mumbai, Chandigarh and Guwahati, microzonation, which examines how soil and rock in a locale would respond to an earthquake, would also be needed, he added.

Printer friendly page
Send this article to Friends by E-Mail

National