The entire Himalayan arc is poised to produce a sequence of great earthquakes, and the next big quake -- of the magnitude of 8 or above on the Richter scale -- may occur during our lifetime, says a study reviewing geological, historical, and geophysical data, according to PTI.
The human toll of such an event in the densely populated countries across the arc is likely to be unprecedented, the researchers said.
So, why do earthquakes occur?
Why is it that places in India, like Mumbai or Bengaluru, experience fewer earthquakes in their entire history, than countries like Japan and New Zealand face in a month.
It is important, then, to understand the history of earthquakes in the region, and why the location is important.
This video explains it:
An earlier report (in 2018) said, earthquakes hitting densely populated mountainous regions, such as the Himalaya, are bigger in magnitude because of a fast tectonic-plate collision.
For the first time, researchers show that the rate at which tectonic plates collide controls the magnitude of earthquakes in mountainous regions. The faster they collide, the cooler the temperatures and the larger the areas that generate earthquakes. This increases the relative number of large earthquakes, they said.
So, "the impact of large earthquakes in mountain belts is devastating," said Luca Dal Zilio from ETH Zurich.
“The entire Himalayan arc extending from the eastern boundary of Arunachal Pradesh (India) in the east to Pakistan (in the west) has in the past been the source of great earthquakes,” study author Steven G. Wesnousky said.
'These earthquakes will occur again and scientifically, it would not be a surprise if the next great earthquake occurred in our lifetimes. But the resolution of our studies is at best on the order of 100 years, longer than a human lifetime,' said Wesnousky, a professor of geology and seismology and director of the Center for Neotectonic Studies at the University of Nevada at Reno, US.
Here’s a video to show you how the Himalayas were formed:
“The Himalayan faults, as shown in the paper, are poised to produce an 8-plus magnitude earthquake. So yes, we are staring at a big one in the future. How far from now no one can tell,” says Seismologist Supriyo Mitra.
Major cities along and close to the Himalayan frontal thrust include Chandigarh and Dehradun in India; and Kathmandu, Nepal.
Strong and damaging shaking in such great quakes could extend southward as far as India's capital, Delhi, one of the largest cities in the world with a population of more than 11 million, Wesnousky added.
North India has witnessed many earthquakes of small magnitude in the past four months, raising popular speculation about a big one in the region. However, he said, scientists have yet to find a systematic relationship between the occurrence of small earthquakes and the timing of greater earthquakes in the future.
'These small earthquakes are thousands of times smaller than the great earthquakes we are studying,' he said.
(With inputs from PTI)