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Magnitude-5 aftershock rocks China quake lake; troops blast debris with anti-tank weapons

Magnitude-5 aftershock rocks China quake lake; troops blast debris with anti-tank weapons

Chinese soldiers used anti-tank weapons to blast away rocks and mud holding back waters in an earthquake-formed lake that threatens more than 1 million people living downstream.
The Tangjiashan "quake lake," formed when a landslide set off by the massive May 12 earthquake blocked the flow of the Tongkou River, has continued swelling despite a hastily dug diversion canal to ease pressure on the barrier.
Managing the lake was the latest challenge for Chinese government, which was working to head off another catastrophe even as it cares for the 5 million left homeless by the quake that killed nearly 70,000 people. More than 1.3 million people live downriver from Tangjiashan.
About 120 People's Liberation Army troops were sent Monday to the lake to continue the draining operation, which included workers deepening the diversion channel and others digging a second spillway.
Soldiers had been firing ammunition at debris Sunday, according to images on television and official Web sites. The operation successfully dislodged debris to speed the drainage, though the level of the lake was still rising with inflow from the blocked river behind the dam, Xinhua News Agency reported.
The water level was more than 6 feet (2 meters) above the mouth of the spillway, Xinhua said. Authorities were on alert both for increased rainfall and new aftershocks that could weaken the dam or send more debris plunging into the lake.
David Petley, a geography professor at the University of Durham in northeast England, warned the situation at the lake appeared to be reaching crisis levels.
"The teams on the dam are fighting a desperate battle now," Petley said. "The outcome is very uncertain."
Rising water levels indicate the outflow is not fast enough, he said. At the same time, news photos show worrisome signs, he said, pointing to indications that the top of the dam was holding, instead of eroding slowly as it should, while the channel further down was eroding too quickly.
That potentially could place increased pressure on the dam by suddenly sucking down large volumes of water, overwhelming the barrier, Petley said.
"I am increasingly concerned about the state of play as the level of the lake continues to rise and the channel at the crest of the dam does not appear to be eroding," he said.
New landslides sparked by a magnitude 5 aftershock Sunday underscored the threat of flooding.
Another magnitude 5 aftershock rattled parts of the quake zone Monday afternoon, including the Tangjiashan lake. Experts at the scene said the dam was safe after the quake, Xinhua reported.
The 10-second temblor sent people in the hard-hit county of Wenchuan rushing out of shaking buildings and tents, Xinhua said. There were no immediate reports of damage or casualties.
More than 250,000 people downstream from Tangjiashan lake have been evacuated in recent weeks, adding to the turmoil created by last month's massive earthquake in China's Sichuan province. Many were living in improvised camps on surrounding hillsides, surviving on instant noodles and suffering from heat, mosquitoes, and a lack of water for bathing.
The death toll from the quake climbed Monday to 69,142, with 17,551 people still missing.
The Tangjiashan lake is the largest of more than 30 created by last month's quake. Government experts quoted by state media have played down the threat of imminent flooding, though a variety of factors could set off a dam collapse: rain, aftershocks, landslides and increased leakage from the barrier.


Updated : 2021-05-09 01:55 GMT+08:00