Lahar exercise a world first

Ruapehu Bulletin, 20 August 1991, Page 3

Lahar exercise a world first

Thirteen hundred skiers were "saved" from death by lahar at Whakapapa last Tuesday in an exercise held to test the area's disaster warning svstem.

Civil Defence officials were at the exercise, carried out by Department of Conservation and Ruapehu Alpine Lifts staff, to observe the procedures developed to deal with a massive mudflow caused by an eruptiQn of the Ruapehu Crater Lake. It was the first time the system has been physically tested, involving members of the public, and was claimed to be the first test of its kind in the world. The lahar warning system starts with seismic monitors at the Crater Lake which warn of an eruption. An eruption warning automatically triggers an alarm in the Knoll Ridge and Te Heu Heu Valley area, the Waterfall T Bar area, and at the Whakapapa Village. The alarm is an air-raid type device which is followed by loud-speaker instructions advising people where to move to to get out of the path of the lahar. Clockwork Assistant civil defence commissioner Keith Dixon said the evacuation worked like clockwork, with Pinnacles Platter cleared in just a few minutes and the Waterfall Chairlift unloaded

in about eight minutes. These areas have been affected by lahars in the past, with damage caused in 1969 and 1975. Mr Dixon said in last week's exercise scenario, lahar material flowed down from the crater, split to flow into the Te Heu Heu Valley and the Waterfall Gully, then rejoined near the Pinnacles , Platter drive station and flowed over into Skippers Canyon. Material would have flowed through the Waterfall Express chairlift to a depth of three metres, he said. Once into Skipper's Canyon little is seen of the lahar until it reaches the Whakapapa Village, so the Top of the Bruce is relatively safe. In Tuesday 's scenario

the road bridge above the village was 'taken out' as were three cabins in the motor camp and two houses in Hepi Terrace wiped out. Water and power would have been cut. Department of Conservation field centre manager Russell Montgomery said the evacuation of the village went very well. He said a lahar would take about 15 minutes to reach the village. In the exercise they allowed 10 minutes to evacuate the areas threatened and this was achieved. Shopping list Mr Dixon said normally there is 'a shopping list' of changes needed after such an exercise but in this case only minor modifications were deemed necessary. Mr Montgomery said handling such an emerTurnpage4