A day after parents staged an impromptu rally in Mianzhu on Saturday,the Communist Party’s top local official,Jiang Guohua,came to plead with the protesters to not carry out their plan to march to Chengdu,the provincial capital,where they sought to prevail on higher-level authorities.Mr.Jiang,on his knees,failed to deter the parents,who shouted in his face and continued their march.
Scientists in China and the U.S.have published new reports examining the possibility that a giant dam may have helped to trigger last May's massive earthquake in China's Sichuan province,renewing controversy over the devastation and other dam-building projects across China's earthquake-prone western regions.
Evidence remains unclear on what effect the added pressure of water collected behind one dam would have on an earthquake of that size.The Zipingpu Dam is 5.5 kilometers away from the epicenter of the Sichuan quake,a 7.9 magnitude temblor.It killed about 80,000 people.
The dam was built 500 meters from the earthquake's fault line.A research paper by a group of Chinese scientists concluded that the weight of collected water clearly affected seismic activity.'It is worthwhile to further study if the effect played a role' in triggering the quake,according to an abstract of the paper published in the December issue of the Chinese Journal of Geology and Seismology.
Separately,Christian Klose,a researcher at Columbia University,put the extra weight of water in the area at about 320 million tons,without mentioning the dam by name.He said it 'amplified the strain on the earth's crust' in a way that would alter the stresses below.
In China,debate could have an impact on plans to build even more dams.A group of 62 Chinese environmentalists and scientists has already appealed for a moratorium on dam construction in the region pending further study of the risks.The government -- and some Chinese scientists -- has said there is no connection between the dam and the quake.
Scientists discovered 10 years after the Hoover Dam was built in 1935 that its reservoir was increasing seismic activity.Since then,it has been well established that other human endeavors can set off powerful tremors beneath the earth's surface.These include coal mining,quarrying,oil drilling,and the injection of wastewater into the ground.Along China's Three Gorges Dam,officials acknowledge that seismic activity has increased slightly since the 400-mile reservoir began filling eight years ago.
Proving that such projects cause large earthquakes is another matter.'What was the rate of seismic activity in the area before the dam was built,and did that rate increase after the dam began to fill with water?' says Ross Stein,a geophysicist at the United States Geological Survey and member of a team that published a 'stress analysis' of the Sichuan quake.'In the absence of that,' he adds,'it's a very hard case to make.
