Rumble in the Himalayas.(study forecasts massive earthquakes in India)(Brief Article)(Statistical Data Included)

Images of the devastating earthquake that hit Gujarat, India, last January have yet to fade from memory: buildings reduced to rubble, weeping relatives, the occasional dust-and blood-covered survivor miraculously plucked from the wreckage. That magnitude-7.6 quake, with an epicenter near the city of Bhuj, was India's deadliest ever, wiping out more than 20,000 people. Now, a study published last week in the journal Science says Bhuj may be a mere shiver compared with what lies in store for the subcontinent. The Gujarat quake, says the report, distracts attention from the region where the greatest loss of life should be expected: the 2,100-kilometer Himalayan arc, which stretches from Kashmir in the west to Bhutan in the east. This is the site of the greatest continental collision on earth, where the Indian tectonic plate is ramming northward against Eurasia. Its progress is slow--about 2 centimeters per year--but energy has been building up over the centuries. Eventually the rock must fracture, allowing the Indian plate to lurch northward beneath the Himalayas.

This rupture (read: massive earthquake) is overdue. Geologist Roger Bilham of the University of Colorado in Boulder, the study's lead author, says the fault line running along the whole length of the Himalayas is set to crack. But it won't go all at once. Based on a re- examination of the region's seismic history for the past 300 years and on new GPS satellite data, he and his colleagues estimate that it would take at least seven massive earthquakes, each affecting a 200km to 300km strip of the fault line, to permit the entire plate boundary to slip. Each quake may have a magnitude of at least 8, depending on the timing and severity of the region's most recent disturbance.

Not only would these quakes be more powerful than the Bhuj disaster, but they would occur in more densely populated areas. The danger zone encompasses the capitals of Bangladesh, Bhutan, India, Nepal and Pakistan, and several other cities with populations in excess of 1 million. Several dams, including the massive Tehri hydroelectric dam in Uttar Pradesh, haven't been built to withstand earthquakes. If the Tehri dam broke, it could kill 10 million people. In all, 50 million people are at risk. "If one of the large earthquakes occurred in Delhi, with a population of [13] million," says Bilham, "the fatality count might be unprecedented. It could be 10 percent of the population."