Seismic activity has increased at Mt Ruapehu after the lake in the volcano's crater peaked in temperature.
Tremors under Mt Ruapehu have been occurring at a "higher than normal rate", according to GNS volcanologist Brad Scott.
Scott said an increase in volcanic tremor at Mt Ruapehu began on October 18, where a "sharp increase was noted before the energy declined a day later".
Mt Ruapehu's Crater Lake had been heating at a rate of 1C per day until it reached a peak of 40C on October 4. It has since cooled slightly and is now about 37C.
Tremor increases happened again on October 25 and 28, and the intensity of the tremor remains higher than normal.