Tamatea Intermediate School's volcano studies took on unexpected realism as Tongariro erupted in front of a fifth of the school's pupils on a trek during their end-of-year camp yesterday.
As part of their studies, pupils had been making their own volcanoes, complete with explosions, teacher and camp leader Paul Lowes told Hawke's Bay Today from the Mission Bay camp where the 90 Year 8 children and 10 teachers and parents are staying.
Lessons came to life on the Tongariro Track when ash and gas burst from the Te Maari Crater shortly before 1.30pm.
"We weren't too close, but we got a marvellous view," Mr Lowes said. Using cellphones, leaders were able to advise principal Roy Sye immediately that the group was safe.
Mr Sye, who had been to the area last week with another group of pupils, was in Wellington yesterday but was able to broadcast the good news to worried families who had begun flooding school telephones with calls.
But what had been a moment of fear back home was being taken in stride by the children, as they got "fantastic photos and fantastic footage", Mr Lowes said.
"The ash cloud rose and rose," before the wind began to disperse it away from the group, which had arrived in the area aboard two Nimons buses on Monday and is due back at the school tomorrow afternoon.
After the mountain silently blasted ash and gas two kilometres into the sky on the western side of the mountain, police and Department of Conservation (DoC) staff closed the Tongariro Alpine Crossing at Ketetahi and Mangatepopo roads..
DoC community relations manager Kim Alexander-Turia said about 50 people were thought to be on the crossing at the time of the eruption. All were thought to be safe.
GNS Science duty volcanologist Nico Fournier said there was "essentially one explosion, and it was not sustained".
Little effect was being seen in Hawke's Bay last night, although there was some disruption of flights between Napier and Auckland.
One early evening arrival was 50 minutes late, and passengers on the back flight to Auckland were told it was being rerouted to avoid any possible ash cloud and would take about one hour, 45 minutes, rather than the usual hour, and one flight in each direction was cancelled.
Hawke's Bay Civil Defence emergency management controller Ian Macdonald said late in the afternoon ash was falling northeast of the mountain and was not expected to affect the Bay.