Scientists are working on recovering $80,000 worth of equipment placed on Mount Tongariro before last month's eruption.
A GPS receiver and two seismic instruments were stationed 200 metres from the main Te Maari Crater on Tongariro when the first signs of volcanic unrest occurred in July.
GNS Science volcanologist Craig Miller says the GPS receiver has been found and the seismic instruments located.
He says although the equipment is damaged, it has important data about volcanic activity leading up to the eruption.
"Some of the instruments were sending their data in real time so we've collected data right up until the last second."
Mr Miller said scientists want to recover the equipment to get that last hour of information. Other instruments were intentionally buried so might still be in working condition.
The eruption from Mount Tongariro on 6 August sent ash over a wide area, closed roads for several hours and disrupted flights.
