Dams and Earthquakes

Chinese press finally covers story that Zipingpu reservoir may have induced deadly quake

(February 20, 2009) After several weeks of widespread international media coverage of the theory that the Zipingpu dam reservoir played a role in triggering the deadly Sichuan earthquake of May 2008, China’s official Xinhua news agency has finally published an article online discussing the theory.

The story, first covered here on the pages of Three Gorges Probe, later in Science magazine, then in virtually every major media outlet around the world outside of China, explains the theory of a growing number of scientists who believe that the dam’s reservoir triggered the deadly earthquake with its weight and by increasing pore pressure in the fault line below it.

The quake was the country’s worst natural disaster in three decades, claiming 80,000 lives and leaving 5 million homeless. The possibility that the calamity was a man-made disaster makes it a politically explosive issue. The fact that it wasn’t covered in the Chinese press suggests it was a banned subject.

Now Xinhua says that Chinese and American geophysical experts with the Sichuan Bureau of Geological Exploration and Exploitation of Mineral Resources, Japan’s National Institute of Advanced Industrial Science and Technology and Columbia University have seismic evidence and analysis of the phenomenon called “reservoir induced seismicity” to back their theory.

Detractors, meanwhile, including a member of the Chinese Academy of Sciences who refused to be identified by Xinhua and Chinese experts at a Canadian polytechnic and Texas Tech, dismiss the link on the grounds that the earthquake was so powerful that it must have been due to massive tectonic pressures alone, and the reservoir was so small by comparison that its effect in the region was “like scratching your foot while wearing a dozen boots.” No reservoir has ever produced such a large earthquake and Zipingpu isn’t the largest of dams in the region by far, making the link unlikely they say.

That scientific logic doesn’t cut it with geophysical experts who think the possibility that Zipingpu triggered the Sichuan earthquake must be investigated carefully given that hundreds of old dams and new ones planned for the region may create a similar risk.

Meanwhile, Xinhua makes no mention of the fact that Chinese authorities are thwarting that very investigation by withholding crucial seismic and reservoir-level data on Zipingpu. If the increasingly credible theory that Zipingpu played a role in triggering a magnitude 7.9 earthquake is indeed unfounded, then releasing the data for scientists to analyze would help confirm that position. That the data continues to remain a closely guarded secret of the Chinese authorities leads many independent researchers to ask: what do they have to hide?

[read Xinhua’s original story]

Jameson Berkow, Probe International, February 20, 2009

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