Mount Tongariro has erupted, GNS Science reports.
The eruption came from Te Maari Crater, on the western side of the mountain, about 1.30pm.
A massive plume of ash can be seen coming from the mountain.
Tongariro, in the centre of the North Island, erupted in August for the first time in 115 years, sending ash as far east as Napier.
According to GeoNet, Tongariro is a complex of multiple volcanic cones constructed over a period of 275,000 years.
The mountain’s active vents include Te Maari, Emerald, North Crater and Red Crater.
Last week GNS Science increased the likelihood of neighbouring volcano Mt Ruapehu erupting, following increased activity on the mountain.