'Great Himalayan Quake' may occur in India

Saturday's devastating Nepal earthquake, though a big one, may not be the Great Himalayan Earthquake scientists have anticipated for a long time.

US geo-scientist Roger Bilham, who had predicted two decades ago the chances of a big quake in the western Himalayas with a magnitude of more than 8 on the Richter scale, said larger quakes are possible to the west of the epicentre of the Nepal quake—an area covering the Kumaon-Garhwal region in India.

“Larger earthquakes are possible to the west of Saturday's earthquake. We do not understand the way in which Himalayan earthquakes are segmented. This earthquake bridged a gap between two large historical earthquakes (in 1934 and 1505),” Bilham, a veteran researcher at the US’ University of Colorado, told Deccan Herald on Sunday.

Working with several Indian scientists over many years, Bilham identified a “seismic gap” in the central Himalayas—between Kathmandu in Nepal and Dehra Dun in India—that has not seen a large earthquake over the past 200 years.
They believe the number of smaller earthquakes are not good enough to release the stress accumulated over the years, and that the likelihood of an earthquake with magnitude of over 8 was serious. 

“We know the inevitable outcome. The lock holding the spring will break, propelling the Himalayas southwards in a giant earthquake. And when this happens, the impact on human life and property and the national economies of India and Nepal will be catastrophic because the central parts of the Himalayas face the cultivated plains of the Ganges and populous cities of north India,” Bilham had said in an interview to a science magazine in 2001.

Asked if Saturday's temblor could contribute to the big one, Bilham said, “Yes it can. But in the past the increased stress from one earthquake has not triggered a second nearby major earthquake in the Himalayas. This does not mean one should not be vigilant for such a possibility.” 

Mike Taylor, a geophysicist with the University of Kansas, who had reported a previously unknown seismically active fault in Nepal in January 2014, told Deccan Herald: “Nepal and the surrounding mountainous communities have experienced devastating events like this in the past, and they will continue to occur. Geo-scientists have long recognised the significant seismic hazards associated with the Himalayas.”

Future catastrophic earthquakes would indeed occur, and several regions were considered sufficiently stressed to witness a major earthquake in the future, said Bilham, who has studied the Himalayas and the Indian plate extensively.