Aftershocks hit brimming China quake lake

Chinese troops are carving a third drainage channel into the unstable dam holding back a big "quake lake," as water levels rise and aftershocks send more debris tumbling into the water, state media reported on Monday.

Soldiers are also using short-range missiles and dynamite to blast apart boulders blocking the first channel, to speed up the flow of water, the official Xinhua agency said.

The Tangjiashan lake rose nearly a meter in 24 hours to Monday morning, and already stood over two meters above the drainage channel even though it only began operating on Saturday.

The massive barrier of rocks and mud was created in mid-May when a major quake shook China's southwestern Sichuan province, sending part of a mountainside crashing into the Tongkou river.

If the dam gives way it will create a floodwave that could threaten up to 1.3 million people downstream, many already forced from their homes by the quake.

Over 250,000 have been evacuated as a precaution.

The arrival of China's rainy season is an additional worry. The large catchment area for the lake, the biggest of around 30 created by the quake, means that 2 millimeters of rain could cause a water level rise of 1 meter, Xinhua has said.

"If the lake level does not start to at least stabilize, and preferably fall, soon then the danger level will rise substantially. This remains a deeply worrying situation," said landslide expert David Petley, Wilson Professor at Durham University, adding that aftershocks were an on-going worry.