An upgrade to the eruption detection system on Mt Ruapehu is underway.
The mountain's last eruption, in September 2007, almost killed two climbers and a snow groomer driver who had to flee a fast-moving lahar.
The Department of Conservation says about half the eruptions on Ruapehu were not predictable with the old technology.
DoC says new sensors and new communication systems will mean it will be easier to detect eruptions and more information will be conveyed reliably to skiers and departmental personnel.
The last major step is the building of a new bunker on the volcano, to house equipment.
It will be built above the Whakapapa ski field at an altitude of 2500 metres. Work is due to be completed next summer.
