WELLINGTON, Jan 29 (Reuters) - A crater lake on a New Zealand volcano used as a backdrop in the "Lord of the Rings" films is on the verge of collapsing and could send a torrent of muddy water down the mountain in coming weeks, media reported on Monday. Melting snow on Mount Ruapehu has filled the lake to within 1.5 metres (5 feet) of its lip, according to the New Zealand Herald newspaper. The 2,797-metre (9,177-feet) volcano is the highest mountain in the North Island and home to two commercial ski fields. Scientists say a lahar, or mudflow composed of volcanic material and water, is inevitable as warm summer weather causes the snow to melt and fill the lake. "It is still expected the earliest the dam might start collapsing to create a lahar down the Whangaehu River is February/March," the Herald quoted a Department of Conservation official as saying. On Dec. 24, 1953, a lahar rushing down the Whangaehu River destroyed a railway bridge, causing a packed passenger train to plunge into the river, killing 151 people on board. Since then, a barrier of boulders and gravel has been built to divert any lahar flowing into the river. No major towns would be in its path. Mount Ruapehu, which last erupted in 1995 and 1996, creating the present crater dam, is in Tongariro National Park, where Peter Jackson filmed some scenes for his "Lord of the Rings".
