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Lahar Warnings on Ruapehu Ski Areas

Lahar Warnings on Ruapehu Ski Areas


we’re skiing on a very active volcano. In the past we have had serious volcanic mudflows called lahars coming down through the skilled with no alarm system. So we got a quite a serious situation which we have to manage. These volcanic mudflows are really hazardous. We’ve actually measured them at up to 90
kilometres an hour moving down the mountain, through where people are skiing. 90 km per hour is far faster than people can ski The lahar is full of snow, ash and some boulders – it’s going to bowl you over and drown you and smash you against rocks – so the message is all about trying to get people out of the way. GeoNet New Zealand’s natural hazard monitoring system has a whole lot of seismometers spread throughout the National Park. Several of those have got blast detectors – little pressure sensors. This system Eruption Detection System or EDS that we have got on the mountain system draws information from GNS equipment that’s in the park From an eruption to the top of the ski field we’ve got about 90 seconds before it hits the ski field and so people need to react really quickly When there is an eruption those sensors detect the data and it sends a message here to these speakers and that then sets the alarms off. [sound of alarm] The warning system consists of speakers in the three main lahar paths – where people are in danger, so we’ve got speakers where they need to be, but we haven’t got speakers where they don’t need to be. Loudspeaker: “Move immediately out of valleys to high ground. This is a volcanic emergency… …A lahar is expected to pass through the ski area” This warning system needs to be as effective as it can but it depends on a lot of things. it depends on people hearing it,
and people knowing what to do, and then doing it. This is a fantastic place to ski, there’s great terrain to ski, but if you’re in the bottom of the valley when there is a lahar siren going, that message to people is to get out of
the valley. During tests like the one you have just seen we have people on the ground watching what people do and how people
move and we add up the numbers of people in the risk zone at the
beginning of the warning and at the end and we look at the percentage of people
who get to safety. This graph shows the results of these observations from
tests over several years. For each test there is a proportion of people skiing who are
at risk at the start of the test and a smaller proportion who have still not
got out of the way by the end of the test. And in this last year we can see
about 72% of people were at risk at the start and a bit over 10% we’re at risk at the end. It can mean anywhere from a few people to maybe forty or fifty
people are still left at risk on the ski area We also conduct surveys awareness
of the skiers and we ask them a range of questions including what’s the right
thing to do when there’s lahar warning and we see in the green bars
we know the proportion of people who know all the correct actions in the blue
bar we can see about 10 percent of people in this year knew some of the actions but the the tan
bars are still in the thirty to forty percent range which concerns us. That’s thirty to forty percent of people who don’t know what to do. We’ve developed a range of education
materials: we have posters and brochures with hazard maps on them and warning
information. We’ve added to that with signs added to the lift towers asking
people questions about mudflows and telling them what to do. The most
important message is: If you’re on the ski field and hear the siren move out of the valleys onto the ridges nearby. We’re continuing to conduct
communications and education research every year to come up with new ideas to
further improve people’s response. The systems we have here particularly the
EDS system is a unique system obviously in New Zealand and also around the world. We’ve got a number of partners that support this system such as the
Department of Conservation, GeoNet, EQC and obviously RAL, the ski field.

5 thoughts on “Lahar Warnings on Ruapehu Ski Areas”

  1. Not all of the people on the skifields will speak English and certainly not all will know what a lahar is. Granted 90 seconds is not much time, will people from countries where there are no volcanoes understand the warnings in time to make themselves safe?

  2. hey stupid what the hell are you doing on that thing? those things go boom and can kill a lot of people including you. ok, just stay there and play while a torrent of mud and rock comes after you. you won't do that again!

  3. Not all of the people on the skifields will speak English and certainly not all will know what a lahar is. Granted 90 seconds is not much time, will people from countries where there are no volcanoes understand the warnings in time to make themselves safe?

  4. 90 seconds is not going to work. Sorry but relocate or accept that warning system is pointless. This is a perfect example of compromising until a non functional theory of a system is acceptable because of 'stakeholders concerns'. You should move the ski hill to a slope that does not get lahars. You already are pushing it with the whole 'ski hill on an active volcano' thing, how much tempting fate is too much?

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