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Seismologists Say Collision of Indian, Eurasian Plates Caused South Asia Quake


Deep beneath the breathtaking, tall mountain ranges of the Himalayas is a divide that has been producing violent tremors for centuries. On Saturday, a powerful collision between these plates unleashed the devastating earthquake in Kashmir that has killed at least 25,000 people.

Seismologists say Saturday's 7.6 magnitude earthquake in Kashmir was hardly surprising. Some have long warned of an imminent great earthquake in the Himalayas.

Scientists say the Indian subcontinent has been moving northward by four centimeters a year and colliding with the Eurasian continent. That movement has over time created the tall mountain ranges of the Himalayas, the Karakoram, the Pamir and the Hindu Kush in India, Pakistan, Afghanistan and Nepal.

As the Indian plate moves northward, it is pushed beneath the Eurasian plate. This movement is accommodated by a slip on a number of major fault zones. Experts say Saturday's earthquake, with an epicenter 10 kilometers from Muzaffarabad, Pakistan, probably occurred on one of these faults.

Ravender Chandha is a seismologist at India's National Geophysical Research Institute.

"The earthquake occurred along the thrust fault," he explained. "The Indian plate going below the Eurasian plate - that is the boundary and these boundaries are marked by main boundary faults. It was essentially a thrust movement that has created this earthquake in the region."

Great earthquakes in the Himalayan region have occurred from time to time but without any kind of predictable interval.

A 7.5 tremor in the Kangra region in 1905 killed about 20,000 people. In 1935, 30,000 people perished in Quetta, Pakistan after a big tremor.

Saturday's quake is the second deadly tremor in Asia in less than a year. Last December, a magnitude nine earthquake off Indonesia's northern Sumatra island triggered the massive tsunami that hit a dozen countries along the Indian Ocean. Since then, Asia has been rattled by a number of medium to large earthquakes.

Mr. Chandha says Saturday's tremor may be linked to the Sumatra quake but there is no conclusive evidence yet.

"There is a belief that the Sumatra earthquake, because it was a huge event that it shook the whole planet, even the rotation of the earth was affected, can possibly trigger these kinds of earthquakes in different places," he said.

Mr. Chandha says it is possible that the South Asia quake would trigger tremors. He says earthquakes would likely occur close to the vicinity of the Saturday's epicenter but probably would be of smaller magnitude. However, scientists stress they are years away from accurately predicting when or where the next big one will happen.

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