Mt Tongariro has continued to emit steam and gas but beneath the mountain, things have been quiet so far this year.
The Te Maari craters, the site of eruptions in August and November last year, continue to be active with continuous emissions of steam and volcanic gas, GNS Science said.
The gas was coming from a large fumarole and crack in a cliff just east of the Upper Te Maari crater.
The main Upper Te Maari crater is also discharging gas but at a lesser rate.
"Gas and steam emissions from the volcano will continue to be a feature of the mountain for several years to come," GNS head vulcanologist Gill Jolly said.
GNS Science vulcanologists are planning to take new gas measurements to compare with those made at the end of December.
Aerial observations at the end of last year showed a large amount of material had filled in the Upper Te Maari crater in the November 21 eruption but the main shape of the crater had not changed.
Meanwhile seismic activity had remained relatively low, with no earthquakes yet recorded beneath the mountain this year.
GNS said Tongariro continued to be in a heightened state of unrest and eruptions could occur with little or no warning.
- Manawatu Standard