Here in New Zealand we woke Tuesday morning to news that Mount Tongariro had erupted – briefly, but with enough vigour to send ash falling over my home town, Napier. I don’t live there these days, but I have family who do.
It was the first eruption of Tongariro since 1897 and came by surprise. New Zealand has an excellent seismograph and volcano warning system – there are live webcams in the craters. Here’s White Island’s, complete with dinosaur. But this Tongariro eruption was left-field. It’s officially over as I write this – Geological and Nuclear Sciences have reduced the danger level - but White Island also erupted last week and Ruapehu is on heightened alert.
All these are tiddlers beside Lake Taupo, an active caldera in the same league as Toba and Yellowstone. The last big eruption, Hatepe, was around 180-230 AD and coated the central plateau with ash. It also gave the Romans and Chinese wonderful sunsets. The Oruanui eruption, around 26,500 years before the present, was the largest the world has seen in the last 70,000 years. It changed the structure of the lake, obliterated everything in the central North Island, and sent dust whipping through the upper air worldwide.
The immediate risk, though, is Auckland. William Hobson chose the site in 1841 on the back of musket wars politics. Nobody knew, then, that it was atop a lava field. That’s why there are so many small extinct volcanoes – they’re driven from one source, and it erupts in a new place, usually, every time. Maori knew. Rangitoto – that island in the middle of the Waitemata – means ‘bleeding sky’. Hmmn…
Copyright © Matthew Wright 2012