Ruapehu won't move out of Volcanic Alert Level 2 for some time

Source: 1News

Mount Ruapehu won't be moving out of Volcanic Alert Level 2 for some time, a volcanologist says.

This comes despite a steam plume being seen above the crater lake for 45 minutes on Tuesday morning. It rose up to 1.5km in the air.

There has been elevated volcanic unrest on the mountain for the last six weeks and in the last week it has recorded its strongest tremor in 20 years.

Geoff Kilgour, a volcanologist with GNS Science, told Breakfast the plume was another example of the volcano showing signs of unrest.

READ MORE: Scientists optimistic for Ruapehu ski season as steam plume rises

He explained a steam plume is generated when the crater lake is warm but the air around it is still.

No seismic or acoustic activity accompanied the plume's appearance, indicating it was not generated by strong activity in the lake.

Kilgour said GNS Science had sent up a plane to do an observation flight as they were "concerned enough" about making sure they hadn't missed anything to do with the lake.

He repeated GNS Science's words from Tuesday, saying this doesn't mean minor activity hasn't occurred.

The crater lake temperature is now around 39C.

Kilgour said magma is pushing towards the crater lake, so further changes in Ruapehu's chemistry and temperature will be seen. More sulphur dioxide will also be present in the volcano's gas emissions.

Due to this, he said Ruapehu won't be moving out of Volcanic Alert Level 2 for some time.

He said higher alert levels are reserved for an eruption. GNS Science can't predict an eruption, but Kilgour said Ruapehu is clearly heating up and unrest is building as the tremors do.

More steam plumes could also be seen over the coming weeks and months under suitable weather conditions.