Air New Zealand says flights in and out of Rotorua are back on, but Taupo, Gisborne airports remain affected by a predicted ash cloud following the eruption of Mt Tongariro yesteday.
Tongariro's Te Maari crater erupted for about five minutes on Wednesday afternoon, sending a plume of ash and gas up to 4km into the air.
GNS Science says the eruption - which occurred without any warning - appears to be over, but they haven't ruled out further eruptions over the next few weeks.
There was a similar sized eruption from the same crater in August.
Air New Zealand says it's cancelled 10 flights on Thursday morning at this stage, but the airline will continue to monitor the situation.
Some early flights from other regional airports will also be affected as aircraft will need to be repositioned following disruptions on Wednesday.
The volcanic alert level remains at two, which signals minor eruptive activity. The aviation colour code has been decreased from red to orange, indicating that a volcanic eruption is underway, but with little or no ash being produced.
August's eruption sent rocks smashing into nearby Ketetahi Hut but Wednesday's burst only contained ash and gas, Conservation Department spokeswoman Kim Turia told NZ Newswire.
Light winds meant the plume went straight up and dissipated, but Civil Defence officials said volcanic ash could fall downwind to the east and people in affected regions should stay indoors.
Last week, GNS warned there was increased activity underneath nearby Mt Ruapehu but scientists have dismissed a link between the two.
In August, the upper Te Maari Crater erupted for the first time in more than a century, sending rocks falling within 1km of the crater.
CROSSING CLOSED FOR AT LEAST 3 DAYS
The Department of Conservation says the decision to re-open the Tongariro Crossing on Labour Weekend in October was the right one.
The crossing was closed on Wednesday following the eruption from Te Maari Crater on Mt Tongariro about 1:30pm which pushed a plume of ash and gas about 2km into the air.
In August the crater erupted for the first time in more than a century, ejecting rocks that fell up to 1km away and forcing the closure of the popular Tongariro Crossing track for trampers.
It was re-opened at Labour Weekend and there were a number of trampers on the mountain, including up to 90 school students, who had to hurry off the mountain when it erupted on Wednesday.
But DOC Ruapehu area manager Jonathan Maxwell said he didn't regret the crossing being reopened.
"We'd had a fairly stable time after the initial eruption," he told Radio New Zealand.
"We have a rahui (restriction) in place a kilometre around that Te Maari crater. That proved to be a good call and the right distance so no one was anywhere near it."
Mr Maxwell said the crossing would be closed for at least three days, after which a new assessment would be made.
He said anyone wanting to view the mountain on Thursday would be best to do so from State Highway 46, which was safe and provided a good view.
Mr Maxwell said the crossing was important for businesses in the area, but that would play a small part in the decision on when to re-open it.
"That is a factor but it's not the paramount factor. The paramount factor is the safety and obviously we do not compromise that."
NZN / 3 News