Mitigating the lahar risk at Whakapapa Ski Area, Mt Ruapehu : public perceptions and the effectiveness of the new warning system

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Leonard, G.S.; Johnston, D.M.; Paton, D. 2004 Mitigating the lahar risk at Whakapapa Ski Area, Mt Ruapehu : public perceptions and the effectiveness of the new warning system Institute of Geological & Nuclear Sciences science report 2004/02 46 p.

Abstract: Surveys conducted around the last three annual tests of the Eruption Detection System (EDS) at Whakapapa Ski Area, Mt Ruapehu, New Zealand, indicate a strong need for increased staff and public awareness of what to do when the alarm sounds. Two additional studies of public perceptions of (a) Ruapehu’s volcanic hazard and (b) the EDS have also been conducted and indicate a significant drop in awareness of the EDS (50 % aware in 2000 down to 37 % in 2003) while awareness of volcanic hazards remains steadily high. The EDS automatically triggers a siren and loud-speaker announcement across the ski area in an eruption. Water from Crater Lake has been ejected into the catchment above the ski area in three eruptions in the last 35 years, creating potentially deadly lahars (dense volcanic-ash-saturated flash floods) down several ski runs. On hearing the alarm skiers have as little as 90 seconds to clear the lahars’ paths on the highest runs. The proportion of skiers aware of the EDS who knew that the correct action in an alarm was to ‘move out of the valleys’ decreased from 79 % in 2000 to 66 % in 2003 (there is currently no public education regarding the EDS). There is increasing confusion of the hazard posed by an impending Crater Lake rim partial collapse (no hazard to the ski area), with the eruption lahar hazard to the ski area discussed here. Audibility of the siren in the last two tests has been apparently continuous across the ski area, but the announcement is not always understandable due to environmental conditions, skier noise or hearing impairment. Therefore, the only way to ensure that all skiers follow the correct actions when the EDS is activated is to ensure that they have prior knowledge through education. The annual EDS tests themselves appear to be acting as an effective educational tool for annually returning customers; 37 % of those aware of the EDS in 2003 had been present for at least one test. Staff receive lahar training each year, but the tests also give them hands-on training of the correct actions to take in an alarm. In the two tests in which staff were alerted prior to the test their actions were more effective at moving people to safety and keeping them calm, than the year in which the test was triggered ‘unannounced’. This has been attributed to staff choosing to learn critical information in the hours between being informed and conducting the test. A public education program involving posters and brochures is underway as a product of this ongoing research, in conjunction with the Department of Conservation and Ruapehu Alpine Lifts. Several recommendations for staff training are also made, especially an increase in testing to at least twice annually – once at the beginning of the season with staff aware, to act as a training exercise, and once late in the season ‘unannounced’ to test the EDS’s effectiveness. Ongoing cooperative research continues to feed back into the education process and the EDS itself, in an integrated system of (a) warning system maintenance and enhancement, (b) education, (c) research and (d) response planning. This integrated system is seen as an essential model for warning system development for a wide range of environmental hazards. (auth)