Brimming crater lake ready to burst

By JO-MARIE BROWN

Dramatic images of Mt Ruapehu's crater lake reveal that time may be running out before a mudslide breaks from the volcano's summit.

Since March 1999, when the first of these pictures was taken, the crater lake has risen 52m and is filling at a rate of 5300cu m a day.

Department of Conservation scientist Harry Keys said the lake was now 96 per cent full and a lahar - a volcanic mudslide - could occur as early as November.

When it does, water, mud and debris will burst through a 7m-high wall of ash which surrounds the crater rim, and run down the mountain's southern side through the Whangaehu Valley.

The present lake level is 1.9m below the base of the ash wall.

An estimated 60 lahars have swept down that path in the past 150 years, including one in 1953 which killed 151 people at Tangiwai.

The Government has ruled out undertaking engineering work at the rim to drain the lake before a lahar occurs, and has installed a warning system on the mountain.

National MP Nick Smith yesterday accused the Government of dismissing civil defence advice about the dangers of a lahar. He told Parliament that earthworks on the crater rim taking "just three days' work with a bulldozer, costing $68,000" would prevent a lahar forming.

He claims the Government is allowing "political correctness" over Maori sensitivity and the environmental movement to influence it.

Yesterday, Dr Keys brought forward by two months his prediction of the next possible lahar because the extremely wet summer meant the lake had filled faster than usual.

But winter would slow the rate.

Although it was impossible to predict the size or exact timing of the lahar, Dr Keys said it was likely to be "a relatively large event" and would probably occur once the water level crept 5m or so up the dam.