This afternoon's small eruption at the Te Maari crater on Mount Tongariro appears to be over, GNS Science reports.
Accordingly, GNS scientists have now decreased the Aviation Colour Code from Red to Orange, signalling that ash is no longer being emitted.
However, minor eruptive activity continues and the Volcanic Alert Level remains at 2.
GNS reports that the eruption occured in the Upper Te Maari crater, in the same area that erupted on August 6th this year.
However, today's eruption did not produce any directed rock blasts or debris flows like those made in the previous explosion.
Today's eruption happened at 1.25 pm and lasted for less than 5 minutes, with local earthquake activity continuing for about 15 minutes.
GNS Science staff Nico Fournier, Agnes Mazot and Craig Miller witnessed the eruption from a few kilometres away.
"We didn't hear anything but could suddenly see an ominous dark grey cloud of ash drifting towards us" said Fournier.
The eruption was also seen by trampers walking on the Tongariro Crossing. Ash erupted during the first few minutes reached 3 km to 4 km height and was clearly seen from Taupo.
There are no reports of injury.
Further eruptions possible
GNS also said that this afternoon's eruption occurred without any measured precursory changes, highlighting the unpredictable nature of volcanoes.
Senior Volcano Geophysicist Steve Sherburn told ONE News there no warning signs before the eruption.
"One of the key things is there was absolutely no warning of this the seismic stations we have monitoring Tongariro showed no activity before the eruption at all."
Sherburn said there are no volcanic patterns emerging because nature seems to be "throwing us curve balls at the moment".
GNS also said that any further eruptions are not expected to escalate in size.
"We cannot say what will happen next at Tongariro but the scenario considered most likely, based on the August 2012 eruption and the description of late 1890's eruptions, is that we could expect another eruption of similar size at any time during the next few weeks," scientists said.
Light dusting of ash
Locals are reporting a light dusting of ash on their properties, following the eruption of a crater on Mount Tongariro this afternoon.
"The families in the south east corner say they have got a very light dusting of ash," local resident Bubs Smith told ONE News.
"I suppose Tongariro has had a big cough, it's got the ash cloud circling around, but on the north east side there's still a bit of ash to come down," he said earlier.
A light dusting of ash fell across part of State Highway 46 and northeast towards Turangi but no more ash has been reported this afternoon as the gas and steam cloud drifts towards the south east.
Ash is being collected this afternoon and will be analysed at Massey University to assess potential human and animal health effects, GNS reported.
At this stage, Wellington Airport has only cancelled two afternoon flights between Taupo and Wellington.
Airways NZ said they are working with the airlines to ensure their flight paths are well above or around the cloud of ash and steam coming from the eruption.
Taupo police report that there are no road closures in place at this stage, but advises people against sight-seeing trips to the area.
"We don't want unnecessary congestion to contend with, and want to ensure the road network remains free-flowing just in case there is any further volcanic activity," said Inspector Steve Bullock.
According to GNS, Tongariro is a complex of multiple volcanic cones constructed over a period of 275,000 years.
The active vents include Te Mri, Emerald, North Crater and Red Crater.
There have been five reported eruptions from the Te Mri craters between 1855 and 1897 but they have been dormant until 2012.