Quake-prone
September 21, 2011
Some 55 million years ago, the so-called Indian tectonic plate broke of from the supercontinent, Gondwanaland, and collided with the Eurasian plate. The impact of the collision resulted in the creation of the Himalayan Mountains, the highest and youngest in the world.
Even now, the Indian plate continues to edge towards central Asia - by about 47 millimeters every year. It is this geological shift that makes the Himalayan region prone to earthquakes. The two plates put pressure on each other and destabilize the layers of the earth's crust.
According to the scientific journal "Nature Geoscience," geological changes taking place well below the earth's surface are also creating tensions under the its outermost shell. Scientists are apparently surprised that the Indian plate has not stabilized after impacting on the Eurasian plate.
Computer simulations
A software program called 'Underworld code' has been developed to help understand how the collision between the plates took place millions of years ago. Statistical analyses can help show the structure of the tectonic plates before and after the collision, and what kind of geological impact the changes might have had.
Thanks to their research, scientists now know that the upper surface of the Indian tectonic plate is much denser than its inner layers, or the mantle and this explains why it is still moving towards Central Asia. The upper crust of earth's surface is collapsing under the impact, dragging the continental plate down with it. The dense upper layer can thus easily sink into the mantle and the pull frequently manifests itself in the form of an earthquake.
India has been divided into four zones according to the degree of vulnerability towards earthquakes: Uttarakhand, Srinagar in Indian-administered Kashmir, Himachal Pradesh and parts of Bihar. The Kutch region in Gujarat and the northeastern part of India fall into a fifth, highly sensitive, category. Since 1934, five high intensity earthquakes have occurred in the Himalayas, causing extensive damage.
Author: Onkar Singh/ mg
Editor: Grahame Lucas