The Zipingpu Dam before the earthquake.

Should we blame a reservoir close to the epicenter for giving a deadly boost to the 8.0-magnitude earthquake, which hit southwest China's Sichuan Province on May 12, or was the quake merely the result of nature's wrath?

International scientists are heatedly debating the possible link between the quake and the Zipingpu Reservoir, 5.5 kilometers from the quake's epicenter in the southeast part of Wenchuan county.

The country's worst natural disaster in three decades, the earthquake claimed more than 69,000 lives and left five million people homeless.

Some Chinese and American scientists argued that the 156-meter-high Zipingpu Dam was evidence of another case of reservoir-induced seismic activity (RIS), while other scientists challenged the claim.

Lei Xinglin, a geophysicist at the National Institute of Advanced Industrial Science and Technology in Tsukuba, Japan, said preliminary research showed the filling and releasing of water in the Zipingpu reservoir from the end of 2007 to May 2008 "affected" the earthquake activities in that area.

"We found the number of quakes increased during the reservoir's filling period, ... and the epicenters of quakes clustered in the southwest and southeast areas around the reservoir during the water releasing period," Lei and his co-workers wrote in a paper in the Chinese geosciences journal "Seismology and Geology" last December.

However, a member of the Chinese Academy of Sciences (CAS) who refused to be named said the Wenchuan tremor did not demonstrate the features of a reservoir-triggered quake.

"A RIS has a unique vertical fault movement, but what happened during the the Wenchuan earthquake was quite the opposite," the CAS member said.