January

Lahar due on one of New Zealand's most active volcanoes

A lahar is due to occur as early February or March 2007 on Mount Ruapehu, in the North Island's Tongariro National Park, one of the most active of around 30 crater lake volcanoes in the world.

Weather is one of the factors contributing to when the lahar is likely to happen.

'Probably the very low percentage (probability) would be in a couple of weeks time, if suddenly the heavens opened up and we got increased snow melt and everything went that way,' says Department of Conservation senior community relations officer Dave Wakelin.

'We'd like to think it was going to happen somewhere around about February-March or March-April but once you start moving in towards April you start getting cooler conditions, you can get the first of the snows and the frosts. . . and that would mean we'd have to go through to next summer.

'It would be nice to think that we got it out of the way this summer but it's going to be very dependent on nature, not us.'

The local tourism industry will be largely unaffected by the lahar and tourism operators are confident that their businesses will carry on as normal when the lahar occurs.

'The processes and procedures that have been put in place by DOC, along with the early warning detection systems give us confidence that this mitigates any risk to our business. Everyone in Whakapapa has been kept well informed and staff have been trained to respond in the unlikely event of an evacuation,' says Kathy Guy, General Manager of Bayview Wairakei Resort and Bayview Chateau Tongariro.

Eruptions in 1995 and 1996 from Mount Ruapehu emptied the Crater Lake and deposited tephra (ash, sandy particles and larger material) over the former lake outlet at the top of the Whangaehu River.

This material has formed a barrier of unconsolidated debris expected to collapse as the Crater Lake rises behind it, resulting in a lahar.

A lahar is a flash flood of water containing volcanic debris caused by water suddenly pouring out of a crater lake. Lahars are a normal part of Mt Ruapehu's behaviour.

The Whangaehu River is one of the most active lahar paths in the world.

The Department of Conservation (DOC), Civil Defence and Ruapehu District Council have taken many measures in preparation for the lahar. The likely path and effects of the lahar are known.

The only risk is to people or property in the lahar path. Risk to the public can be avoided by listening to, and following advice from Civil Defence before and during the event.

Further information:

Dave Wakelin
Department of Conservation
Phone +64 7 386 8607
Mobile +64 274 313 643
Email dwakelin@doc.govt.nz