Causes for concern

India and southern Tibet are moving towards each other by two metres a century The strain is not deforming the rock much but is accumulating instead

Up to 50 million people could be at risk across Bangladesh, Bhutan, India, Nepal and Pakistan, the researchers say.

Five major earthquakes have struck India in the last decade but according to geologists the worst may be yet to come.

The prediction is based on several lines of geological evidence that point to potential large earthquakes in the region.

Today, about 50 million people are at risk from great Himalayan earthquakes, many of them in the towns and villages in the Ganges plain.

Authors Bilham, Gaur and Molnar, Science

The Himalaya are situated at a point where two of the tectonic plates that make up the surface layer of the Earth meet.

Global Positioning System measurements show that India and Tibet are moving closer together by around 20 millimetres every year.

The movement creates pressure across the Himalayan region, and the only way to release this pressure is through earthquakes, says a team of scientists led by Roger Bilham at the University of Colorado in Boulder, US.

The last big earthquake in India caused huge damage

There have been six major Himalayan earthquakes in the past 200 years, they say, the most recent in 1950.

"The population of India has doubled since the last great Himalayan earthquake in 1950," the scientists say in the journal Science.

"The urban population in the Ganges plain has increased by a factor of 10 since the 1905 earthquake, when collapsing buildings killed 19,500 people.

"Today, about 50 million people are at risk from great Himalayan earthquakes, many of them in towns and villages in the Ganges plain."