KEY POINTS:
Mt Ruapehu's Crater Lake could cascade into the Whangaehu River as early as mid-January.
A lahar warning has been increased to 2 with low to moderate risk of the dam breaking, Department of Conservation staff said after visiting the lake on Friday, the Wanganui Chronicle reports today.
The lake level is now 2.8 metres below the top of a dam of loose volcanic material thrown there by the mountain's 1995-96 eruptions.
Seepage through the dam was also noticeable and was happening at 10 litres a second, DOC said.
There was also a wave hazard at the lake caused by large chunks of ice suddenly falling into the water.
People have been warned to keep away from the water's edge.
Water is expected to break through the dam and cascade down the mountain in the bed of the Whangaehu River some time after it rises another 0.7 of a metre.
This could happen as early as mid-January but could take longer, DOC said.
If the lake's water gets to the top of the dam before it collapses, the lahar created will be 10 to 30 per cent bigger than the one that caused the Tangiwai Disaster in 1953.
This time, however, there are warning systems in place and roads and bridges are to be closed.
- NZPA
