On the 17th March 2013 I wrote about the risks posed by a volcanic eruption in the Auckland Volcanic Field. I posed a number of questions as much as anything, since as a geologist, I go on evidence, and frankly, I was at a loss to find any. I don’t live in Auckland, so I don’t have any particular interest beyond an odd-hours research, but since writing this story, I’ve seen an escalation in interest in the issue. Might it be that there is more evidence than originally reported? Well there is a follow-up story in the NZ Herald today which raises several more issues which I want to address:
1. Focus of activity – The story probably creates unnecessary fear because it suggests that each of the old active volcanic craters in the Auckland Volcanic Field is active. This is unlikely. More probably an eruption is going to be in the Rangitoto Island area, if not the existing cone.
2. Eruption history – It suggests that Rangitoto has a sporadic eruption history of up to 1000 years. This is less important than the nature of the eruption. Really the threat posed is from an early blast rather than a later flows of liquid, highly fluid magma. Since the eruption is probably going to be offshore, I suggest the greater threat is a mini-tsunami in the bay, as well as a volcanoclastic surge blasting your windows to smithereens. You might want to rethink that bay-side waterfront apartment acquisition; if only for the high rents and the surge risk.
3. Eruption activity – The evidence suggests that volcanic activity has increased in intensity, i.e. the latest eruption some 500 years ago from Rangitoto Island was the most activity in terms of lava flow and ash. Where does that leave us? Maybe more explosive coming? Maybe simmer or subside.
It goes without saying that Auckland is unique in the world. It is not unknown for cities to be built adjoining volcanoes. The problem for Auckland is that it is probably the only place that I know which is actually built on top of a volcanic field. Having said that; the next eruption is probably going to be offshore. Let’s not forget how ‘recent’ human arrival was; and I’m including the Maoris.
Does it make sense to rethink the focal of NZ development? Does it make sense to keep developing Auckland? Well, given the characteristic of these types of volcanoes, I think it does make sense to keep developing Auckland. Does it make sense to retain it as the centre or focal point for NZ development? Perhaps not; but then expensive housing prices are probably destined to drive people out. Who wants a bird’s eye view of a volcaniclastic surge? Not me.
The reality is that there is a great deal to question about the nature of this volcanic phenomenon. Does one lead one’s future in the hands of academic volcanologists with a limited understanding of geological events? Such volcanologists are really learning as they go, largely on the basis of empirical evidence. They have not even observed an eruption from any field with this style of eruption; let alone from this volcanic field. Reason for caution? Not really perhaps until the evidence trail grows.
Associate Professor Phil Shane said: “Future planning would have to consider living with active volcanism for a long period of time….It is not as bizarre as it sounds, if you think about Iceland and Hawaii - societies have gotten used to living with volcanic activity for generations”.I have a problem with this statement insofar as Hawaii and Iceland are a completely different type of eruption centre; both in terms of style and character. I doubt there is even the evidence to suggest that Auckland is even a ‘hot spot’ in the conventional sense. Certainly not like Hawaii with its flood basalts, or Iceland for that matter. I suspect its origins are more tectonic than is appreciated, with activity arising from a fractures opening up offshore of Auckland. The evidence is simply not there. There is a major kink in the tectonic plate at Wellington, and you can bet no work has been done interpreting earthquake activity offshore from Auckland.
The problem too often with ‘empirically-driven’ scientists is that they only start questioning convention when some event jumps up in front of them to tell them how little they know about the world (having an incomplete geological account due to erosion and limited observation) and not a great deal of knowledge about the cause of the Auckland Volcanic Field. In this last respect, these empiricists are largely ‘talking blind’. There are not too many geologists around who say ‘I don’t know’. Neither are there many people who define themselves as ‘critical geologists’. Everyone wants to fall back on convention to convey how much they know. The flipside is that unpopular academics seems to be a contradiction in terms, hence you cannot always expect volcanologists (indeed any scientist with unconventional ideas to get taken seriously). Can you imagine how safe one must get with life-time tenure? Can you imagine how annoying a person could become if you worked opposite a professor you did not like for a lifetime? My sense is that they grow to get along; much like the Japanese, defined by their own sense of safety.
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