Thursday, February 5, 2009

An Earthquake-Causing Dam?

The idea that last year's Sichuan earthquake was caused by the Zipingpu dam is an idea that seems to be picking up steam.

From The Associated Press:

BEIJING (AP) — Pressure from a dam, its reservoir's heavy waters weighing on geologic fault lines, may have helped trigger China's devastating earthquake last May, some scientists say, in a finding that suggests human activity played a role in the disaster.

The magnitude-7.9 quake in Sichuan province was China's worst in a generation, causing 70,000 deaths and leaving 5 million homeless. Just 550 yards (meters) from the fault line and 3.5 miles (5.5 kilometers) from the epicenter stands the 511-foot-high (156-meter-high) Zipingpu dam, the area's largest. The quake cracked Zipingpu, forcing the reservoir to be drained.

Fan Xiao, a chief engineer at the Sichuan Geology and Mineral Bureau, said Wednesday that the immense weight of Zipingpu's waters — 315 million tons — likely affected the timing and magnitude of the quake. Though earthquakes are not rare in the area, one of such magnitude had not occurred for thousands of years, Fan said.

"I'm not saying the earthquake would not have happened without the dam, but the presence of the massive Zipingpu dam may have changed the size or time of the quake, thus creating a more violent quake," Fan said in a telephone interview.

Seismologists recognize that large bodies of water may exert pressure on fault lines deep in the earth, leading to earthquakes. The pressure can push the sides of fault lines harder together, increasing friction, or cause the fault lines to slip apart.

Read On
The article later on quotes scientists who do not think that a dam could have "caused" the earthquake. Although they do concede that dams may have had something to do with the timing and intensity.

I can't see this controversy over the Sichuan earthquake being caused by a dam ever turning into an explosive issue. Although the dam was very near the epicenter of the quake, the cause and effect between dams and earthquakes seems to be conjecture. I'm not sure how one would ever prove such claims.

The scientist who is most convinced of the connection is doing everything he can to thwart the building of future dams though. China, for years, has been on a dam-building fix.

Despite any challenges from academics, I can't imagine China would stop building dams any time soon.

1 comment:

Sage said...

Mark: I'm a freelancer writing a series of articles on study abroad in China. I'd love to ask you a few questions about Xi'an. If you're willing, please email me at sage_dillon AT yahoo.com.