GNS Science volcanologist Brad Scott said, “After the second eruption in November we now have to consider the possibility that Tongariro might have entered an eruptive episode and this unrest could continue for several months. Within an episode Tongariro might quietly discharge steam most of the time, but occasionally have small eruptions with little or no warning. There was a similar episode of activity in the 1890s”.

GNS Science head volcanologist Gill Jolly said, “There is still a lot we don't know about the recent activity and this means it is difficult to be certain what will happen over the next few months. Unfortunately with active volcanoes nothing is black and white and our best assessments still have a lot of uncertainty”.

“What we can say is that eruptions substantially larger than that on 6 August should give us some warning signs and at the moment we don't see any such signs ”, said Dr Jolly. In recent days GNS Science have received several reports of possible eruptions, but these have been normal steam discharge coupled with fine weather and light winds making for a prominent steam and gas plume.

There has been only minor seismic activity at Tongariro since 21 November, and no volcanic gas measurements last week due to poor weather and high winds. Gas may continue to be smelt downwind from Tongariro and be a minor irritant.

Background

The Volcanic Alert Level ranges from 0 to 5 and defines the current status at a volcano. Level 1 indicates volcanic unrest, with departures from background levels.

Aviation Colour Codes are based on four colours and are intended for quick reference only in the international civil aviation community. Code Yellow indicates that volcanic activity has decreased significantly but continues to be closely monitored.