This afternoon's eruption on Mt Tongariro caught scientists by surprise and has left them unsure what will happen next at the volcano.
Senior Volcano Geophysicist at GNS, Steve Sherburn, told ONE News there could be more activity in the next few weeks.
"I think for the next week or two weeks at least we're possibly in a situation where we may get additional activity - it's really hard to work out. This is the difficulty of dealing with a volcano like Tongariro."
The eruption lasted for about five minutes and sent an ash plume 3km into the sky.
No-one was injured and nearby residents have reported just a light dusting of ash on their properties. However, scientists are now struggling to predict what might happen next.
"One of the key things is there was absolutely no warning of this," Sherburn said. "The seismic stations we have monitoring Tongariro showed no activity before the eruption at all.
"Nature seems to be throwing us curve balls at the moment."
Witnesses say the eruption in the Te Maari Crater came 'out of the blue' with no ground shaking or increased activity at the vent.
It came from the the same crater as another blast in August which covered the local area in ash and forced the Department of Conservation to close off walking tracks.
However, within days the seismic activity around the volcano had dropped and the area was deemed safe again, making today's events all the more surprising.
"Because the eruption in August was the first for 100 years we don't know what a normal pattern of activity is," Sherburn said.
"We do know in the 1880's and 1890's Tongariro did have a series of eruptions over a few months, and what we were thinking was the eruption earlier this year wasn't going to be followed by anything at all because everything was trending back to normal," Sherburn said.
Pressure has also been building beneath the crater lake of the nearby Mt Ruapehu and it has been suggested the heightened activity beneath both volcanoes could be linked.
However, Sherburn said he believes it is just a coincidence, "but I'd be glad for someone to prove me wrong".