Scientists are warning Mount Tongariro may erupt again as the Department of Conservation looks at re-opening the remainder of the iconic Tongariro Crossing next month.
GNS Science say emissions of steam and a gas plume have been a continuous feature of the mountain since the August 2012 eruption.
Scientist Tony Hurst said the volcano is still in an "active" state.
"Therefore we have to be prepared there will be other events like that without any warning," said GNS Scientist Tony Hurst.
The risk of another eruption is causing concern for the Department of Conservation as it prepares to reopen the northern section of the Tongariro Crossing which was damaged in the August eruption.
Department of Conservation Ruapehu Area Manager Jonathan Maxwell told ONE News the eruption had not dampened the popularity of the 19.4 kilometre walking track.
He said DOC was forced to close an access way to the track shortly before Christmas when tourists began flocking to the area.
"It's become a destination so in the end total anarchy broke out with cars and buses," said Maxwell.
"There were wing mirrors being knocked off and cars damaged as well as people trying to park in incredibly stupid places."
GNS Scientists are also concerned neighbouring Mt Ruapehu may be due to erupt.
Gas samples show there could be a blockage underneath the volcano's surface. The blockage could burst and erupt without warning.
Tourism operator Stewart Barclay from Adrift Outdoors said tourism on Mt Ruaphu and Mt Tongariro is reliant on the findings of GNS scientists.
"We can't do anything until the scientists scratch their heads and reckon it's all safe to go up," said Barclay.
DOC has closed the area within 2km of the centre of crater lake at the summit of Mt Ruapehu.