China "quake lake" fears prompt new evacuation

BEICHUAN, China (Reuters) - China has evacuated more than150,000 people living below an swollen lake formed by thismonth's devastating earthquake amid fears it could burst andtrigger massive flooding, state media said on Wednesday.

The Tangjiashan lake was created when landslides caused bythe May 12 earthquake blocked the Jianjiang river above thetown and county of Beichuan in mountainous Sichuan province,near the epicentre of China's most destructive earthquake indecades.

The official death toll from the 7.9 magnitude quake wasraised on Tuesday to 67,183, and was certain to rise further as20,790 are listed as missing. The quake injured nearly 362,000people and new aftershocks toppled 420,000 houses, many alreadyuninhabitable, on Tuesday.

Downstream from the lake, residents were evacuatedovernight as engineers dug a diversion channel to preventflooding.

Up to 1.3 million people from 33 townships of Mianyang citycould be relocated if the lake barrier collapses entirely, theChina Daily said in its online edition.

Residents of Taihong looked on as the landslide demolishedtheir village. Han Haiyun, 60, was lucky to be away from herhouse at the time.

"I would never have thought something like this couldhappen in my life," she said. "...It's impossible to put intowords."

The water level in the lake, one of 35 "quake lakes" formedby the tremor and holding the volume of about 50,000Olympic-size swimming pools, has kept rising and the giantsluice would not be ready for another week, the China Dailyquoted experts as saying.

Immediately below the lake, the river runs in a loopbetween flattened high- and low-rise buildings, but threatenscommunities downstream which held evacuation drills on Tuesday.

In Tianlin village, among the first to be flooded if thelake bursts, gongs and loudspeakers directed 680 villagers torush to surrounding hills within 20 minutes.

The lake water level was 727.09 metres on Tuesday, only24.21 metres below the lowest part of the unstable landslipbarrier.

Beichuan was considering erecting two large gravestones --one engraved with the names of the victims, the other with thenames of volunteers and donors, the Beijing News said.

Over the last century, about 5,500 people have been killedby flash floods when barrier lakes burst through dams made bylandslides, according to a 2004 paper by geologists at theChinese Academy of Sciences.

In 1786, the breach of a landslide dam 10 days after amajor earthquake killed about 100,000 people in Sichuan.

The region along the faultline is densely packed with dams,raising concerns that if either the quake lakes or the weakeneddams burst, the rush of water could cause other dams to fail.

Apart from the threat of flooding disasters, officials aretrying to stave off epidemics as the temperature rises and therainy season approaches.

A massive relief effort, which involves providing food,tents and clothing for millions and the reconstruction ofhousing and infrastructure, is expected to take up to threeyears.

Beijing, host of Summer Olympics, was checking buildingsfor damage and potential quake risk, including dams, schoolsand supermarkets, the Beijing News said.

(Writing by Nick Macfie; additional reporting by Beijingnewsroom; Editing by Alex Richardson)