China courting disaster with dam buildings: Report

A new report reveals that the more than 130 large dams being built in western China are in areas of high seismicity.

It could eventually trigger disasters such as earthquakes and tsunamis.

The report was released by the Canadian-based environmental group Probe International.

In a worst-case scenario, dams could collapse creating a tsunami that would wipe out everything in its path, including downstream dams, and cause untold loss of life and property.

To pierce the Chinese government's secrecy over its dam-building, the Probe report overlays a Chinese map of dam locations with US Geological Survey earthquake data and a United Nations' seismic hazard map. Probe also used Google Earth satellite images to confirm the state of completion of about one-half of the dams.

According to the report, 98.6% of the dams being constructed in western China are located in moderate to very high seismic hazard zones. The Zipingpu Dam, for example, which is now thought to have triggered the
magnitude 7.9 Sichuan earthquake in 2008 that killed an estimated 80,000 people, was built in a moderate seismic zone. The force of that quake cracked the dam and shook it so severely that it sank one metre and
moved 60 centimetres downstream.

The location of large dams near clusters of recorded earthquakes with magnitudes greater than 4.9, and especially when the earthquake focal points are also close to the surface, "is cause for grave concern," said
John Jackson, a geologist and the report's author.

"In addition to the hazard of high natural seismicity in western China, reservoir-induced seismicity is likely to increase the frequency and perhaps the magnitude of earthquakes in this area," he warns.

Especially worrying in this environment, said Mr. Jackson, is the cascade-like positioning of the dams which follow one another so closely there is no terrain between them for energy to dissipate in the event of
catastrophic dam failure.

"If one dam fails, the full force of its ensuing tsunami will be transmitted to the next dam downstream, and so on, potentially creating a deadly domino effect of collapsing dams," he says.

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