China ready to ease pressure on quake lake

CHENGDU (Reuters) - China readied on Friday to easepressure on a swollen "quake lake" threatening hundreds ofthousands of people downstream in the southwestern province ofSichuan as the water level quickly rises toward a man-madesluice.

The Tangjiashan lake is the largest of the more than 30quake lakes formed when the May 12 earthquake triggeredlandslides that blocked rivers, raising fears of a secondarydisaster after the tremor that killed more than 69,000.

Water behind Tangjiashan's natural mud-and-rock dam rose to739.52 metres (2,440 feet) above sea level at 4 a.m. GMT (5a.m. British time), only 48 centimetres from the sluice, statetelevision said, which meant partial discharge of floodwatersbuilding up behind could occur within hours.

But the chance of the unstable dam collapsing was alsoincreasing "under the continuous influences of aftershocks,rainfall and other uncertain factors", the official Xinhua newsagency said.

"Quake lakes" burst weeks after two powerful earthquakeshit the same area in 1786 and 1933 respectively, both killingseveral times more people than those who died directly from thetremors, Xinhua said.

Underscoring the urgency, Premier Wen Jiabao visited thelake on Thursday, urging workers there to ensure there were nocasualties and calling it a "critical moment" for Tangjiashan.

More than 250,000 people have been evacuated inquake-ravaged areas of Beichuan, Mianyang and Jiangyou, addingto the millions already displaced when their homes collapsed orwere badly damaged in the earthquake.

Troops went door-to-door in some evacuated towns downstreamon Thursday to ensure residents had moved to higher ground.

The more than 600 soldiers who opened the 475-metre longsluice have pulled back from Tangjiashan, but some planned toreturn on Friday to dig it deeper, state television said.

The lake also threatens a major fuel pipeline and gasoperations owned by PetroChina and Sinopec.

An estimated 1,000 to 2,000 children have been orphaned bythe quake, an official with the Ministry of Civil Affairs saidon Friday, adding parents who lost their offsprings to thedisaster would be favoured for adoptions of these orphans.

(Writing by Lindsay Beck and Guo Shipeng; Editing by DavidFogarty)