The massive earthquake that hit the Indo-Pakistan border on Saturday is not the great Himalayan earthquake predicted by scientists. That means the worst is yet to come. Though the magnitude of the present earthquake _ 7.6 and large enough to cause widespread destruction and loss of life in Pakistan administered Kashmir and the Indian state of Jammu and Kashmir, it appears that this was not the worse case yet. American and Indian scientists, who have been studying both historic and present earthquake data as well as measuring plate movements, predicted in 2001 that several large intensity quakes are overdue in the Himalayan region. Prof Roger Bilham of the University of Colorado, who has been spearheading the research effort for several years now, said that the Muzaffarabad quake is not the massive quake his team had predicted. The quake was not strong enough to release a build up of energy below the Himalayan range. Only earthquakes of intensity greater than eight could release this pent up energy.``Yes, it was in the right place but not as big as forecast,'' said Prof Bilham, who is currently involved in intensive research on the Sumatra quake that caused the Indian Ocean tsunami.
The latest quake occurred on a thrust fault in the region of collision between the Indian and the Eurasian plates. According to calculations made by Prof Bilham's team, the Indian plate is moving 5-cm closer to the Asian plate each year, while Tibet moves 32-mm closer to the Asian plate each year. As a result, the Kingdom of Nepal is shortened by 18-mm each year.
This is equivalent to the loss of two soccer fields a year along its 600 km-long northern border. The mountains of Tibet, the Tien Shan, and the Himalayas are results of compression caused by plate collision millions of years ago.
The number of great earthquakes known in the past several centuries appears inadequate to accommodate the Himalayan convergence being observed, said Prof Bilham. Hence, the scientist concludes that several earthquakes of magnitude greater than eight may be overdue. ``Due to the increased population and urbanisation in the Ganges plain, the death toll from any one of these earthquakes could now exceed one million. We know only approximately where these future earthquakes will occur and we know considerably less about their timing,'' he said.
The area in focus is a 500-km-to-a-800 km-long segment, popularly known as the Garhwal-Kumaun Himalayas, where earthquakes of magnitude greater than eight have not occurred since historic times. In scientific talk, this segment is referred to as the ``central seismic gap''since it defines an unruptured part of the Himalayan arc. However, a section of Indian experts believe that the absence of any great earthquake in the region in the past century may have something to do with a period of dormancy.
``An assessment of historical and archaeological database from the central Himalaya and the Gangetic Plains leads us to conclude that the central segment of the Himalayas is undergoing an intriguingly long period of quiescence in terms of generation of plate boundary earthquakes,'' said scientists at the Centre for Earth Science Studies, in Trivandrum.
| "On the other hand, who the hell knows?" they added. |