Many Aucklanders know that they live on an active volcanic field, but what would a future eruption be like and when might it happen? What can you do to help yourself if there was an eruption? Dr Jan Lindsay answers these questions.
DR JAN LINDSAY
In a future Auckland volcanic field eruption, we think that the eruption will start with phreatomagmatic activity, which is basically the magma interacting with water and creating an explosion, and that would probably affect all houses and people within a 5-kilometre radius of the vent
So the idea in a future eruption is to evacuate everyone before that phase of the eruption occurs. After a while – we don’t know how long, but it might be days, it might be weeks – a scoria cone is likely to form, and scoria cones form by fire fountaining out hot blobs of rock, in this case, basalt rock, and forming a sort of steep-sided cone, very close to the vent. Now that will be very, very close to the vent. Those rocks won’t travel very far, but by the time that scoria cone forms, everyone will be well and truly out of the way.
And then we have ash, and volcanic ash is the most widespread volcanic hazard, and that can affect a lot of people directly or indirectly because it will fall on people in houses and create a direct problem, if you like. But it will also affect a lot of people and organisations indirectly, because it will close the airport, it will cause havoc on roads, that sort of thing. It’s something that has to be constantly cleaned up.
Interesting to think about how people might cope because I mean the first obvious answer is we really don’t know. However, I think Auckland is in a very good position to respond to this sort of event. We have a really good and strong Civil Defence group. We have a strong group of scientists working on the field. In terms of the public, it is very hard to know how the public will behave. You never know, I mean a lot of people do seem to put the responsibility on the government for bailing them out of this sort of situation, whereas in a natural disaster, really it’s up to the individual to contribute and to help themselves if you like.
I would expect that every Auckland household has a getaway kit and a survival kit of some description so that they could survive for 3 days. And that’s regardless of whatever natural disaster they may face. The first few days, it is really important that individual households can survive with enough food and water for those initial days.
Ministry of Civil Defence and Emergency Management, Auckland Regional Council