Shen Guofang, head of an assessment group for the Three Gorges Dam, acknowledged that the dam can definitely induce earthquakes.
"It is certain that irrigation dams will induce earthquakes, but the magnitude is generally small. They are primarily microseismic or very microseismic. That is because the deep penetration of the reservoir water along the fault would reduce their resistance to shear. Also enormous pressure from the dam itself and from the water will lead to the formation of certain changes in the geological structure.”
Sheng dismissed suggestions that the Three Gorges Dam may have caused the Wenchuan earthquake in May 2008 (8.3M) and the Lushan earthquake in April 2013 (7.0M).
Source: Xinhua, December 18, 2013
http://news.xinhuanet.com/local/2013-12/18/c_125875613.htm