Scientists had no warning before Mt Tongariro eruption
Wednesday 21 Nov 2012 6:18 p.m.
By Tom McRae
Schoolchildren and trampers ran for their lives, not knowing if this was the big one. In the end, Mt Tongariro fired off just the once – but it was scarily spectacular all the same.
Tongariro erupted silently, and with no warning, sending a 2km plume of ash shooting into the sky.
By chance a camera crew were filming the crater when the eruption happened.
The biggest danger from the eruption was to people walking the Tongariro track. Up to 90 Napier schoolchildren were only 1km away when the crater blew.
For the Department of Conservation the priority was to get trampers off the mountain as soon as possible.
The scientists that monitor Tongariro were given no warning. As GNS Science volcanologist Michael Rosenberg explains, there weren’t even the earthquakes that normally precede an eruption.
“The earthquake activity around the north side of Tongariro has been very quiet for a couple of weeks, and there have been no earthquakes in that area that would suggest this was going to happen,” he says.
And they don't believe it's related to recent activity in Ruapehu.
“Each has its own separate body of magma underneath and separate plumbing system to get that magma and fluids up to the surface, so we are not making any connection between the unrest at Ruapehu and this eruption this afternoon.”
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The eruption caused the aviation colour code to be updated to red, meaning there has been a significant emission of ash into the atmosphere. Air New Zealand says the eruption will disrupt flights east of the mountain, and already flights between Taupo and Wellington have been cancelled.
- READ MORE: Tongariro ash cloud – Where will it go?
There are no road closures but police are warning those who are tempted to sight-see to stay away.
This is the second time the Te Maari crater has erupted this year. Shortly before midnight on August 6 an eruption sent blocks of rock flying up to 2km from the crater to damage the Ketetahi Hut, and vents were reactivated that had been covered up since Tongariro last sprung to life in 1896.