A Mig-26 helicopter swings an excavator to the barrier lake in Tangjiashan, Beichuan County, southwest China's Sichuan Province, May 26, 2008. Machinery has been carried from Leigu to Tangjiashan by air and the operation on dynamiting the dam of the barrier lake is speeded up. (Xinhua Photo)
A Mig-26 helicopter carries an excavator to the barrier lake in Tangjiashan, Beichuan County, southwest China's Sichuan Province, May 26, 2008. A Mig-26 helicopter has carried machinery from Leigu to Tangjiashan by air and the operation on dynamiting the dam of the barrier lake is speeded up.(Xinhua Photo)
The Mig-26 helicopter swings an excavator to the quake lake in Tangjiashan, Beichuan County, southwest China's Sichuan Province, May 26, 2008. A Mig-26 helicopter has carried machineries from Leigu in the vicinity of Tangjiashan which could only be reached on foot currently. As heavy machineries are carried into Tangjiashan by air, the operation on dynamite the dam of the quake lake speeded up. (Xinhua Photo)
An excavator is carried to the barrier lake in Tangjiashan, Beichuan County, southwest China's Sichuan Province, May 26, 2008. A Mig-26 helicopter has carried machinery from Leigu to Tangjiashan by air and the operation on dynamiting the dam of the barrier lake is speeded up.(Xinhua Photo)
Excavators start to work in Tangjiashan barrier lake, Beichuan County, southwest China's Sichuan Province, May 26, 2008. Nine machines have been transported here to rescue the swelling Tangjiashan lake, formed by landslides that blocked a river known as the Jianhe after the May 12 earthquake. (Xinhua Photo)
Professionals and materials are airdropped for operations to blow a barrier lake at Tangjiashan, Beichuan County, which was formed by landslides after the May 12 earthquake and now blocks the river Jianhe. (Xinhua Photo)
Armed policemen jump off a truck before they start to walk toward Tangjiashan quake lake in Beichuan county, southwest China's Sichuan Province, May 25, 2008. Armed police troop treked to the quake lake that poses a threat to the dam as airdrop can not be performed due to heavy fog.(Xinhua Photo)
Armed policemen prepare to start to walk toward Tangjiashan quake lake in Beichuan county, southwest China's Sichuan Province, May 25, 2008. Armed police troop treked to the quake lake that poses a threat to the dam as airdrop can not be performed due to heavy fog. (Xinhua Photo)
