NZ research lead to scientific rethink on volcanos | Pacific Beat

NZ research lead to scientific rethink on volcanos

NZ research lead to scientific rethink on volcanos

Updated 23 August 2012, 10:30 AEST

Scientists at Auckland University are excited about the potential of new research on volcano behaviour.

The scientists are studying Rangitoto, Auckland's youngest volcano, and they say the results so far could change their understanding of how volcanos work.

The research is investigating how often a volcano is active and how long it lives.

Presenter:Geraldine Coutts

Speaker:Associate Professor Phil Shane, Auckland University

SHANE: Oh well I think for a long time scientists studying these types of volcanoes like we have in Auckland have always assumed that they sort of only erupt once and over quite a short period, sort of just weeks to months, and then they never erupt again. So if we have future activity we always assume a new little volcano will form somewhere else within the region. But some of our recent research on the youngest one that's erupted in Auckland, that's called Rangitoto, it's an island out in the harbour, it erupted roughly about six or seven hundred years ago, we've been looking at the past records a little bit more detailed and we're starting to get, we haven't published the work yet, but we're just starting to get a lot of data back now showing that it erupted over a longer period in time and erupted more than once. 
COUTTS: Well did you look at Kilauea in Hawaii? How do you regard that because it has lava flow most of the time so is that considered one eruption then if it just doesn't stop?
SHANE: Hawaii's very different, it's a very different sort of volcano, not all volcanoes are the same. In Hawaii yes it's problematic as to do you call that lots of eruptions or just one big continuous eruption. You could argue well there's been activity at Kilauea over the last 20 years almost non-stop, so you could call that just one, one eruption even though it's long-lived. But these ones in Auckland our knowledge of them based on similar sorts of ones overseas, though Hawaii's not a similar sort of one, we would have thought that they're actually quite short-lived, and instead Rangitoto may have erupted over 500 or even a thousand years. And of course we get into the speculative stuff after that. Of course people always start to wonder will there be future eruptions from that actual volcano?
COUTTS: Well now that you've got this data it will change your approach to researching volcanoes, in what way?
SHANE: Well one of the main outcomes is one of our jobs is always to look at what's happened in the past to get some feeling for what could happen in the future, because people, planners and local government always want to know well what's going to happen in the future. And of course these things are very hard to forecast. And I think up until recently we always told them chances are one day but maybe not in our lifetime a new volcano would form in a new location and the activity could well be all over within a year, even though that would be hugely disruptive, that's sort of what we would expect. But actually we now have to consider the option that it could go on for a very long time, maybe even hundreds of years.
COUTTS: Does this help in any way to predict when a volcano might erupt?
SHANE: Well I don't really know if we can predict when a volcano erupts. We'd rather like to see it in the terms of knowing what's happened in the past, we get a better feeling for what could happen in the future. So I know I haven't sort of answered your question directly but that's a really difficult question to answer. But I guess now we're going to look at them a little bit more differently than we did in the past.
COUTTS: And also Auckland is highly susceptible to lava flows, so how does this help you manage that?
SHANE: Well again there's very little you can do other than knowing what areas are most likely to be affected. If we could predict where there'd be a new eruption, although I've just explained that's a very difficult thing to do, at least we've got a good feeling from our work on what's happened in the past to know where lava would go or perhaps even more importantly where ash would blow. Lava can be quite restricted where it goes but there's problems with ash in the atmosphere and that sort of thing. So I guess we've been looking at past ash layers recorded in the geological records. So we're starting to get a bit better picture of where ash would blow and how much and for how long. So we can't really do much about it but at least if we know what happens we know like where to evacuate or when we know we could come back or that sort of thing.
COUTTS: So your analysis has been of previous eruptions and looking at the average length and all the other dimensions to it, so the information's always been there then, it's just basically the way you've interpreted it this time?
SHANE: Well yes it's partly fresh eyes looking at old information, that's part of it. But another part of it is also we've been deliberately ... volcano ash gets preserved in lakes and in swamps and that sort of thing, and we've been deliberately digging into swamps and lake sediment and that sort of thing to look for volcanic ash layers. And that's when we realised that there wasn't just a single ash layer from Rangitoto from any one eruption, there was actually ash spread over geologic time, sort of spread over a longer time than we expected. So a little bit of fresh eyes on old data, but also a little bit of new work too. 
COUTTS: And when will the study be published?
SHANE: Well I guess we're just so busy I wish I could say in a month or two, but we tend to sort of have a backlog of work we want to get done. I suppose it's just really when I have some free time to sit down, make sure that our work is completely water-tight, we don't want to rush off and I just want to check that everything's correct. But I'm hoping in the next six months or something like that.
COUTTS: So you think that Rangitoto's still got some more business to do?
SHANE: Well I think our new work suggests that we just have to look, I wouldn't go as far as right, that's where the next eruption will be. I think that just that we now have to look at these volcanoes a little bit more differently, that it is possible, at least Rangitoto, not the other ones, could come back to life, or alternatively, perhaps even more likely if a new one is formed, that's sort of the old way of thinking of it then well that might keep going on and on and off and on for a very long time.

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