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    Future risk of major Nepal-India earthquake, say scientists

    Synopsis

    The researchers believe that some of this stress has shifted west, to an area stretching from the west of Pokhara in Nepal to the north of Delhi.

    The researchers believe that some of this stress has shifted west, to an area stretching from the west of Pokhara in Nepal to the north of Delhi. 
    LOS ANGELES: Western Nepal and northern India face an increased risk of a future major earthquake, warn scientists who have found that the devastating 7.8 quake that struck Nepal in April released only a fraction of the energy "locked" in the underlying fault.

    Using data from the GPS stations, an accelerometer that measures ground motion in Kathmandu, data from seismological stations around the world, and radar images collected by orbiting satellites, an international team of scientists has pieced together the first complete account of what physically happened during the magnitude 7.8 earthquake that struck near Gorkha, Nepal on April 25, killing nearly 9,000 people.

    "This is a place that needs attention, and if we had an earthquake today, it would be a disaster because of the density of population not just in western Nepal but also in northern India, in the Gangetic plain," Professor Jean-Philippe Avouac, from the University of Cambridge, told BBC News.

    The researchers show that the earthquake occurred on the Main Himalayan Thrust (MHT), the main megathrust fault along which northern India is pushing beneath Eurasia at a rate of about two centimetres per year, driving the Himalayas upward.

    Based on GPS measurements, scientists know that a large portion of this fault is "locked."

    Large earthquakes typically release stress on such locked faults - as the lower tectonic plate (here, the Indian plate) pulls the upper plate (here, the Eurasian plate) downward, strain builds in these locked sections until the upper plate breaks free, releasing strain and producing an earthquake.

    The researchers believe that some of this stress has shifted west, to an area stretching from the west of Pokhara in Nepal to the north of Delhi, the report said.

    There are areas along the fault in western Nepal that are known to be locked and have not experienced a major earthquake since a big one (larger than magnitude 8.5) in 1505.

    The researchers said the new stress that has moved there could already be adding to the tension that has been building up over five centuries.

    The Gorkha earthquake ruptured only a small fraction of the locked zone, so there is still the potential for the locked portion to produce a large earthquake.

    "The Gorkha earthquake didn't do the job of transferring deformation all the way to the front of the Himalaya," said Avouac, also a geologist at Caltech.

    "So the Himalaya could certainly generate larger earthquakes in the future, but we have no idea when," said Avouac.

    The epicentre of the April 25 event was located in the Gorkha District of Nepal, 75 kilometres to the west-northwest of Kathmandu, and propagated eastward at a rate of about 2.8 kilometres per second, causing slip in the north-south direction - a progression that the researchers describe as "unzipping" a section of the locked fault.
    (Catch all the Business News, Breaking News Events and Latest News Updates on The Economic Times.)

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    4 Comments on this Story

    Kollur Brahmam1827 days ago
    As Himalayas is situated in larger thrust zone there may be periodic intense in seismic activity around Himalayan thrust zone. Naturally and rarely a thrust zone causing mountain region is covered the biggest ice sheets whose pressure on the greatest mountain varies as season change and change in rainfall due to greenhouse gases./ The highest mountain range is being swept by greenhouse gases which may cause abrupt and sudden heat changes on the surface of the great mountain regions. Large ice mass is subjected to mass transfer in the form of water causing floods. Mass transfer and flud pressure in the subsurface of the region cause periodic tremors as stress build up periodically. The recent massive earthquake is du to melting of millions of tons of ice and subjected to pull and push of earths rotation and revolution. The Earth along with its shifting masses due to large scale melting and forming floods make the Earth shiver and shake for a moment causing high magnitude earthquake. I am able to say that Himalayas experience periodic tremors and surely and certainly not high magnitude eaerh quake that has happened recently. But distant places may not withstand due thrust zone implications and experience quakes.
    Nam Singh1827 days ago
    An earthquake of 8.5 and above will have an impact like depicted in Armageddon, and unimaginable destruction and loss of life. !!
    hemkant beedkar1827 days ago
    See what happened by the 7.5 magnitude earthquake. Scientists now predicting one of 8.5 magnitude. Taking into consideration this imminent danger the infrastructure to be build in these areas needs quake-resistant properties.And the area under consideration for such precautions must extend upto Nagpur to avoid a very great loss to life and property.
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