Hoping to harness the power of the river, the Chinese government began building the dam a few years ago, expecting to finish by 2009. As the water rises, it will drown more than 1,400 rural towns and villages abandoned earlier by government decree. The water rising behind the dam will power 26 huge turbines to provide electricity, and will allow people to control a river that has killed 300,000 people by flooding during the 20th century. No one knows how local seismic faults will react to the incredible mass of water behind Three Gorges Dam. Like heavy snow on an overloaded roof, the weight of water blocked by dams can cause existing cracks in Earth's crust to slip, resulting in earthquakes.
Faults tend to slip more often when a nearby giant reservoir is filled with water.
The largest was a magnitude 6.5 triggered by the Konya reservoir in Turkey. That earthquake killed 200 people in December 1967. NASA funded Jeff Freymueller and Shusun Li of the Geophysical Institute to help the Chinese determine the seismic risk of Three Gorges Dam. Millions of people downstream from the dam are at risk should an earthquake damage or destroy it. He added that the chances of the dam being destroyed by an earthquake are small, but because the consequences are so severe any seismic activity induced by the reservoir has to be taken seriously.