Gas emissions from Mount Tongariro are continuing to fluctuate following an eruption in August.
GNS Science says three flights recording gas levels have been undertaken in the past few weeks.
It says though they are well below what was recorded soon after the eruption on 6 August, the levels remain abnormal, indicating that the volcanic unrest continues.
The latest flight on Tuesday recorded 540 tonnes a day of sulphur dioxide and carbon dioxide flux of 1340 tonnes per day. This compares with 2100 tonnes of sulphur dioxide three days after the eruption.
GNS Science says teams have now recovered a GPS receiver close to Te Maari crater, which was buried beneath 30 centimetres of ash and debris. It hopes to be able to get data from it.
The volcanic alert remains at level 1.