The idea that people are able to cause earthquakes seems inherently wrong. Yet, in the wake of what has happened in Sichuan, there are reports that perhaps the Three Gorges Dam (TGD) – some 660 km (we wrongly said 200 km earlier) from Wenchuan – is partly responsible for increased seismic action in the area.
The TGD reservoir sits on two major fault lines and the rising water level is straining these fault lines. Probe International (proxy needed) has more:
For seven months after the reservoir-level increase in 2006, Chinese Academy of Engineering scholar Li Wangping says the Three Gorges area registered 822 tremors. So far, none have been severe enough to cause serious damage. But, later this year when the dam’s water level is set to rise to its full 175-meter capacity, the increase in water pressure, in water fluctuation and in land covered by the reservoir, Fan says, makes for a “very large possibility” that the tremors will worsen.
And the TGD is not alone:
Engineers in China blame dams for at least 19 earthquakes over the past five decades, ranging from small tremors to one near Guangdong province’s Xinfengjiang dam in 1962 that registered magnitude 6.1 on the Richter scale – severe enough to topple houses.
I should say here that this is not to suggest any direct link between the dam and the Wenchuan earthquake on Monday afternoon. But it is interesting that when it comes to dams and earthquakes, pro-dammers spend an awful lot of their time assuaging fears that the world’s biggest dam can withstand earthquakes (although it is designed to handle a 7.0 quake, and Monday’s was 7.8 at the epicenter). Xinhua was quick to announce that Monday’s earthquake did not damage the TGD.
However, instead of asking how dams are affected by earthquakes, it seems it may be useful to flip that question around.