China quake a new skirmish in an old battle

The tectonic battle between the Indian subcontinent and the Eurasia Plate has been raging for tens of millions of years, pushing the Himalayas higher and spurring countless earthquakes such as the one that struck central China on Monday.

“India is basically ramming into the rest of Asia,” said John Stix, an earthquake expert at McGill University in Montreal.

The clashing continental plates move an average of 2 inches a year, creating stress along an extensive series of faults throughout Asia.

Monday’s magnitude-7.9 quake released massive amounts of energy along the Longmenshan Fault, which separates the Tibetan Plateau from the Sichuan Basin.

The Tibetan Plateau, pushed by the Indian subcontinent, is gradually moving north and east, rising up and over the hard crust of the Sichuan Basin.

The earthquake probably moved the plates several meters, estimated Kate Hutton, a Caltech seismologist.

“Unfortunately, it’s more of the same – big earthquake in an area of high population with maybe not so great buildings,” Hutton said.

The area’s last major earthquake was a magnitude 7.5 that killed 9,300 people in 1933. Stress had been rebuilding along the fault for at least 75 years, Hutton said.

Globally, earthquakes measuring 7.9 occur about once a year, most centered beneath the oceans.

 alan.zarembo@latimes.com