Kiwi volcanologist says rising Mt Ruapehu temperatures 'typical' but there is 'potential for it to erupt'

It may be rumbling a tad more than usual and its crater lake is warming, but Mt Ruapehu is no more likely to erupt right now than any time in the last year, a Kiwi volcanologist says. 

GNS scientist Graham Leonard has laid to rest excessive fears that Mt Ruapehu is on the brink of eruption after its crater lake has rose one degree every day since last Tuesday.

"It's not something we need to be worrying about any more than last week at the moment. But it is showing a little bit of a change which is quite normal," Mr Leonard said.

Mt Ruapehu goes through a typical cycle of crater lake heating and cooling over a period of months, fluctuating between 12 degrees up to 40 degrees, Mr Leonard said.

"It's quite typical of the last 15 years of Ruapehu to be in this cycle," he said.

But although the North Island's largest mountain has sat at the lowest volcanic alert level for a year now, Mr Leonard did admit it could erupt at any time.

"The thing about volcanoes is their eruptions are not regular, they're uneven in time, so like shuffling a deck of cards you can get a whole bunch of kings, or a whole bunch of eruptions closely spaced in time but it doesn't mean that they're linked," Mr Leonard said.

"They're a long way apart and they're coming from very shallow magma chambers.

"So it's a coincidence that we're seeing eruptions in Hawaii and Central America and Vanuatu at the moment."

Mt Ruapehu is also experiencing an increase in volcanic tremor, and while GNS says the mountain doesn't show any "unusual signs" of unrest they say it is a useful reminder that eruptions can occur with little or no warning.

Volcanic unrest hazards, which are possible from a volcanic alert level one, occur on and near the volcano.

They may include: steam eruptions, volcanic gases, earthquakes, landslides, uplift, subsidence, changes to hot springs, and/or mudflows.

GNS hopes to collect water and gas samples from the crater lake this week.

The Crater Lake on Mt Ruapehu.