(January 28, 2009) Since China’s deadly May 12 earthquake, Fan Xiao, China’s chief engineer of the Regional Geology Investigation Team of the Sichuan Geology and Mineral Bureau, has been a lone voice calling for an investigation into the possibility that the Zipingpu dam reservoir, just a few kilometers from the epicenter, might have induced the earthquake. Now, he is joined by Christian Klose, a geophysical hazards research scientist from Columbia University in New York, who agrees and explains, using geophysical data, how it likely happened.
According to Klose’s presentation to last month’s American Geophysical Union meeting in San Francisco [see Abstract], “Several geophysical observations suggest that this M7.9 earthquake was triggered by local and abnormal mass imbalances on the surface of the Earth’s crust. These observations include (1) elastostatic response of the crust to the mass changes (2) slip distribution of the main rupture, and (3) aftershock distribution.” In other words, says the current issue of Science, the magazine of the American Association for the Advancement of Science, according to Klose, “the added weight both eased the squeeze on the fault, weakening it, and increased the stress tending to rupture the fault. The effect was 25 times that of a year’s worth of natural stress loading from tectonic motions … When the fault did finally rupture, it moved just the way the reservoir loading had encouraged it to…”
Representatives from the Chinese Academy of Science, meanwhile, are denying that the Zipingpu dam had anything but good effects on the region. In China’s own Science Times, dam and earthquake safety engineering experts from the Academy dismiss the idea that Zipingpu induced or triggered the devastating earthquake. But, in the absence of independent scientific analysis and a review of the data on seismic activity and reservoir levels, which Chinese authorities are keeping under wraps, it would be imprudent to dismiss the likelihood that China’s deadly earthquake was, indeed, reservoir induced.
Read more about the debate here:
Top Chinese scientists from the Chinese Academy of Sciences have dismissed the possibility that the Zipingpu dam reservoir could have induced China’s devastating 2008 earthquake, complaining that the media has been “incessantly questioning the wisdom of building more and more hydro dams in earthquake-prone southwest China” in the wake of last year’s quake. Rather than flinch, they argue, China should march forward and build bigger and stronger dams with the capability to withstand earthquakes of greater magnitudes. Read the full story, translated by Three Gorges Probe, here
2) Three Gorges Probe Exclusive: Chinese geologist describes widespread earthquake-damaged dams, says one of them may have triggered China’s deadly quake
Three Gorges Probe asked Fan Xiao, Chief Engineer of the Regional Geology Investigation Team of the Sichuan Geology and Mineral Bureau, China for his reaction to Chinese Academy of Sciences experts’ dismissal of the possibility that the Zipingpu dam induced China’s devastating May 12 earthquake. Read his rebuttal and detailed description of the extensive damage done to China’s dams by the May 12, 2008 earthquake, and why officials must address the urgent question: Did the Zipingpu dam induce the May 12 earthquake? Full story here
3) Science magazine asks the question too: “A Human Trigger for the Great Quake of Sichuan?“*
By Richard A. Kerr and Richard Stone, *Science*, January 16, 2009
Natural disasters are often described as “acts of God,” but within days of last May’s devastating earthquake in China’s Sichuan Province, seismologists in and out of China were quietly wondering whether humans might have had a hand in it. Now, the first researchers have gone public with evidence that stresses from water piled behind the new Zipingpu Dam may have triggered the failure of the nearby fault, a failure that went on to rupture almost 300 kilometers of fault and kill some 80,000 people.
Science reports on Columbia University’s geophysical hazards scientist Christian Klose’s presentation at the Fall Meeting of the American Geophysical Union meeting in San Francisco in which he explained how the added water changed the stresses on the Beichuan fault, tending to rupture it with an effect 25 times that of a year’s worth of natural stress loading from tectonic motions. [see Abstract]
New Scientist‘s Fred Pearce reported in his year-end piece that “probably nowhere on Earth are there so many large dams in an area of such seismic risk. Engineers are astounded that none of the 390 hydroelectric dams damaged in the magnitude 7.9 quake actually collapsed.
The biggest potential disaster, Pearce reports, was averted at the Zipingpu dam, just 17 kilometres from the quake’s epicenter. “Holding back more than a cubic kilometer of water … the hydroelectric dam was the largest of a new, cheap design with a rock core and concrete face. As the tight valley sides juddered, the structure was squeezed and ended up 18 centimeters downstream, and 70 cm lower. The concrete was ripped apart but the core of the dam survived.”
Pearce goes on to explain that had the quake occurred just two months later during the monsoon – when the reservoir would have been full and the stresses on it greater – “Zipingpu and the other dams would probably have failed,” inundating Dujiangyan, a city just downstream of the dam. Engineers managed to empty the reservoir and it now awaits repair.
Three Gorges Probe, January 28, 2009