A teacher who was on Mt Tongariro with a group of 90 students has captured the "absolutely spectacular" eruption of the volcano on video.

GNS Science confirmed the eruption, at the Te Maari crater, happened shortly after 1.20pm. It is the second eruption on the mountain this year; an eruption on August 6 was the first on Tongariro for more than 100 years.

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Tamatea Intermediate teacher Lomi Schaumkel said they were near the Katetahi hot springs when eruption began.

‘‘We were right up there next to it. It was just amazing. It was pretty scary from where we were and it just looked absolutely spectacular, the ash that came out. It really did look like one of those atom bomb explosions, and it made a rumbling sound.’’

There were 90 students, six parents and four teachers in the group.

‘‘Some panicked, some didn’t. Everyone came down safely and it was great’’.



The group were about 1 km away from the eruption, Schaumkel said.

''We saw all these tourists running away from it. We didn't stick around long.''

A further 20 Year 8 pupils from Gulf Harbour School in Whangaparoa were making their way off the track with parents and guides after being just 750m from where the crater erupted.

Two bus drivers from Nimon and Sons, who took the Napier children to the mountain, had reported back to their base that they could see an ash plume 2km high, a spokesman said.



TONGARIRO CROSSING CLOSED

Department of Conservation (DOC) area manager Jonathan Maxwell said 30 to 50 people were being evacuated from the Tongariro Crossing track. No injuries had been reported but the crossing had been closed.



Today's eruption lasted for about five minutes. GNS has updated the alert on Tongariro to level 2, meaning there is "minor eruptive activity". The aviation colour code has been lifted to red, meaning there is "significant emission of ash'' into the atmosphere.



A national advisory has been issued by Civil Defence saying regions from Waikato down to Hawke's Bay could be affected by ash cloud.



"Minor volcanic activity is occurring at Tongariro - Te Maari craters and could be hazardous in the immediate vicinity of the craters.



"Light volcanic ash fall can be anticipated downwind of Tongariro and may impact the following areas or regions: Waikato; Hawkes Bay; Gisborne and Bay of Plenty."

Air New Zealand said tonight it was not expecting to operate services to or from Taupo, Rotorua or Gisborne airports tomorrow morning because of the ash cloud.



Ten services in and out of Taupo, Rotorua and Gisborne have been cancelled so far and the airline says it will continue to assess the situation as the morning progresses.



Some early flights from other regional airports will also be affected as aircraft will need to be repositioned following today’s disruptions.



Genesis Energy was shutting production at its Tongariro hydro scheme site south of Lake Taupo.



Tongariro/Rangipo Prison - which is located near the base of Mt Tongariro, off the Desert Road - was operating as normal at this stage.



Corrections Department central regional manager Terry Buffery said there was no local site impact following the eruption.



''However, robust plans are in place to manage the facility should the situation escalate. Safety is always a priority for staff, prisoners and the public. We are confident in our ability to respond accordingly.''



CREW IN ‘RIGHT PLACE AT THE RIGHT TIME’

Three crew members from Kiwi web-video production company 90 Seconds TV were lucky to be in the "right place at the right time", said chief executive Tim Norton.



The crew were aware of recent geothermal activity and counted themselves lucky to be able to catch close-up footage of the eruption, he said.



''We went into this trip knowing another eruption would happen some day, and sure enough it went up.''



The group were making a Tongariro Crossing video today, joined by two people from Australian Geographic and a representative from Rotorua Airport.



They were shooting a video to encourage Australians to travel to the Great Lakes area.



Norton said the vulcanologist and geologist were in the middle of their on-camera interview when ''she blew her top''.



''I have watched the footage of the explosion. There was a big boom, which lasted quite a while.



''There was quite a lot of euphoria, lots of screaming and yelling. There wasn't a lot of fear.''



He said the fear came later, when the smoke and ash began to pour into the sky.



''I think when that happened, when they felt the rumble deep in the ground, that was a little bit frightening,'' he said.



The crew were about to return to the base of the mountain.



Norton said the latest eruption would do little to put Aussies of travel to New Zealand.



''It will have the opposite effect. They love volcanos and geothermal activity.



''Tongariro will boost tourist numbers.''

STAY INDOORS, SAYS CIVIL DEFENCE



Civil Defence has warned people to stay indoors if ash is present.



"Volcanic ash could be a health hazard, especially if you suffer from breathing difficulty. If outside, seek shelter (e.g. in a car or building)."



It was advising people to close all windows and cover their mouths if caught in the ash. People should stay out of designated restricted zones.



DOC had a helicopter in the air and was canvassing the volcano to see if they could locate anyone on the mountain, a Taupo Council spokeswoman said.



"There is a helicopter looking to see if there's anyone around, any visitors on the mountain to make sure everybody is safe," she said.



Taupo Council's civil defence emergency manager Phil Parker, who coordinated the response last time the volcano erupted, was working with DOC and other organisations.



LAKE ROTOAIRA RESIDENTS ALARMED



Lake Rotoaira resident Robyn Bennett said there was a big, black ash cloud over her house, which was about a kilometre from the eruption site.



"It's just blew her stack," she said.



She said the air smelled of sulphur.



"It's hard to breathe if you go outside, it's pushing out quite heavily." Bennett said she didn't hear the eruption but it looked like a new vent had formed in front of a previous eruption crater. The ash cloud was moving east towards Napier and Taupo.



Ann Lambert, owner of the Rainbow Motel at Tokaanu, near Turangi, said she had not heard any noise, unlike the previous time Tongariro erupted when there had been a "huge loud noise".



"We weren't aware it had happened. We just looked up and saw it," she said.



"It's just a grey cloud at the moment ... It's not as imposing as the last time."



Kathleen Konui, who lives at Otukou Marae "just below" the mountain, said she had heard a sound like a shotgun going off.



"The mountain was all covered with white smoke," she said.



In the hour or so since then the air had cleared, although she could still see some smoke coming from about four holes on the mountain.



"I'm standing here now looking at them."



The sky was too hazy for her to be able to see a plume from the eruption.



At 1.30am this morning a New Zealand Couriers truck driver reported a strong smell of sulphur on the Desert Road while Motuoapoa resident Cindy Greaney said she noticed an "obvious smell of sulphur" at 6am.



HISTORY REPEATS



This is the second eruption this year. The Te Maari crater erupted on August 6, the first time in more than 100 years.



The eruption, on August 6, widened and deepened the crater and reactivated vents which had been covered up in the 116 years since it last erupted in 1896.



Ruapehu has also been active recently but has not erupted. Pressure was building under the volcano and there was an increased likelihood of an eruption, GNS said last week.



The volcanoes are close to each other but scientists did not believe that the activity at both volcanoes was related.



However, they couldn't exclude the possibility, GNS vulcanologist Nico Fournier said earlier this week.



"We don't have evidence at the moment that the activity of the two volcanoes are related," Fournier said. "But we can't exclude it entirely."



GNS vulcanologists were researching if activity at the two volcanoes was connected and also were looking at the relationship between earthquakes and volcanic activity.



A series of earthquakes rattled the ground beneath Tongariro in the weeks leading up to the August eruption and another series of quakes have shaken the ground beneath Ruapehu in the last few weeks.