Man-made trigger likely for China quake
Researchers investigating the cause of the devastating earthquake that shook China's Sichuan Province last May believe it may have been a man-made disaster.According to a report in Science magazine, there is evidence that water piled behind the new Zipingpu Dam may have triggered a nearby fault in a 300km rupture that killed some 80,000 people.
The chief engineer of the Sichuan Geology & Mineral Bureau, Fan Xiao, last month issued the conclusion of his investigation into the disaster, which said pressure from the reservoir had probably affected the timing and scale of the earthquake. Xiao opposed construction of the dam in 2003 amid safety concerns.
Other scientists have reached similar conclusions,. but the news is politically and economically sensitive for China. A report delivered by Christian Klose of Colombia University's School of Engineering to an American Geophysial Union meeting last year stated: "Several geophysical observations suggest that this 7.9 earthquake was triggered by local and abnormal mass imbalances on the surface of the Earth's crust."
He said that the fault had not been activated for thousands of years previously.
Fan has detailed how changing water levels just prior to the quake could have been the trigger: "As we now know, a week before the May 12 earthquake, the water level fell more rapidly than ever before," he said.
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