Auckland: A city waiting to erupt

MARK BROATCH - Sunday Star Times -  27/11/2011

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An Aerial view of Mangere Mountain scoria cone from 2009 showing the two craters and extensive pre-European terracing on the crest and outer slopes. The Auckland Domain volcano from the southeast, showing its large explosion crater and small central scoria cone. An aerial view of the two coalescing explosion craters of Lake Pupuke and surrounding tuff ring from the north. The site of Three Kings volcano showing the extent of the large explosion crater and surrounding, house-covered tuff ring. Big King with its summit water reservoir, upper left, is the only scoria cone that has not been quarried away.

ALASTAIR JAMIESON

LAVA CAVE: Inside the Wiri Lava Cave with its classic Gothic arch cross-section and surge benches on the walls.

MAP: The volcanic cones of Auckland.

 Volcanoes of Auckland: The Essential Guide - AUP

It is not often noted by those who live south of the Bombay (Mumbai?) Hills that 1.5 million Aucklanders share more things than rampant egotism and a love of violent crime - one of them being that they conurbate on several dozen volcanoes.

As I child I virtually grew up on one - the now wonderfully misnamed One Tree Hill, ever since some ideologue took a chainsaw to the stately pine because it wasn't local enough. Before the place became a haven for strollers and camera-happy tourists, we blithely tore up the terraced slopes on our choppers and slid down them on large sheets of cardboard. Good thing they banned kids like us.
And good thing there were people like Governor George Grey, Sir John Logan Campbell, George Winstone, and those many small groups of loud lobbyists - without whom we would be much the volcanically poorer. They saved many endangered peaks and lava caves from being ground down into roads and buildings. And in 1973, world-first rules were passed protecting views of the mountains. Pity this visual-pollution forethought hasn't been matched elsewhere in the city.
For Auckland's volcanic cones - recently upped in number to 55 after four new ones were noticed - are so much more than swathes of green that, had they not been vertical, would probably have been paved over by our frequently philistine local government predecessors. They are our refuges, our points of reference, our vantage spots, the singular destination of coaches of foreigners, places where our kids can harass cows and sheep close up.
When will the next magma arise? The book is unsure, as science must be around anything geological. Rangitoto erupted 600 years ago, but the peak - ho ho - of eruptions occurred in the main in period between 24,000 and 35,000 years ago. "It could be next month or not for thousands of years." Reassuring. We may only have a few days' warning. But the book, written by a geologist, a curator and a heritage consultant, reckons it will probably happen on the isthmus where most Aucklanders live, and bubble up somewhere where it hasn't happened before. Someone call Peter Jackson for the movie rights.
This is an essential guide, every page decked out with a new or historical photograph or clear illustration, and offering more technical information than even geologists will probably need. The mountain-by-mountain pages will be pored over. AUP obviously realised they had one shot to get every possible vulcanophile, and they got the mix right.
My one concern is that the binding of mine came loose after a couple of weeks, but if you love Auckland's volcanoes, and are not sure quite why, get this book.