India is shrinking by 2 cm every year. A new analysis of satellite-based data has given precisely the rate at which the country is shedding size as it pushes northward against the Himalayas.
“India’s size is decreasing by 2 cm every year,” says geophysicist Paramesh Banerjee of the Dehradun-based Wadia Institute of Himalayan Geology. “As India’s size decreases, the thickness of the Himalayas will increase proportionately.” The analysis of data from 1998 onward reveals that the distance between Mussoorie and Badrinath is now 1.5 cm less and decreasing every year. Bangalore and Lhasa in Tibet are also closer by 4 cm.
The results emerged after scientists at Dehradun and the University of California, Berkeley, studied the concealed movement of the Indian plate by measuring distances between 40 Global Positioning System (GPS) stations in India and across Tibet, Australia, Europe, the Middle East and Southeast Asia.
The subcontinent’s northward grind is not new, but latest findings of this journey cannot be dismissed as scientific trivia. A movement of even a few millimetres of the earth’s crust is an indication of possible seismic hazards and future earthquakes. Such hazards are now greater. The 1.5 cm strain in the crust which has accumulated in a 100-km wide zone in the western Himalayan region between Mussoorie and Badrinath is a precursor to future earthquakes. “The accumulation is alarmingly high,” says Banerjee. To understand crustal strain, imagine pressing the ends of a plastic scale till it bends, then snaps.
GPS uses satellites, receivers and software to pinpoint geographic locations. Since India set up GPS networks only by 1998, data of the Indian plate’s drift has gaps. Collaborator Professor Roland Burgmann at the University of California says India and its surrounding plate boundary zones are of “great interest” internationally, given the quake hazard.
With exceptions, Indian GPS data is unavailable to foreign researchers, who rely on published results derived by Indians. “Important questions include the degree to which the Indian subcontinent is getting deformed,” says Burgmann.
Banerjee explains the long-term repercussions of the distance between India’s southern and northern tip (Kanyakumari to Himalayas) shrinking by 2 cm every year. “This means, after 200 million years, there would be no India, only a vast mountain range along the southern coast of China,” he says. While this is the fate of all continents, the immediate worry is impending quakes, he adds.