Huffing and puffing - Ruapehu lets off steam as crater lake temperature rises

Tuesday, 3 May 2022

Freelance journalist Neesha Bremner's photo of a steaming Mt Ruapehu.

It’s huffing and puffing again, but will a steamy Mt Ruapehu blow the house down or is it a case of the boy who cried wolf?

Large plumes of steam were sighted coming from Mt Ruapehu and have been steadily building up since Tuesday morning.

The temperature of the crater lake has also increased from 38C to 39C however, the Volcanic Alert Level remains at Level 2 and the Aviation Colour Code remains at yellow.

Freelance journalist Neesha Bremner, who lives 26km north of the mountain in the settlement of Ōwhango, said she got a phone call from a friend this morning saying steam was building up over the mountain.

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She said locals were certainly not panicking but were keeping a close eye on the mountain as it continued to release clouds of steam, and there was a noticable smell of sulphur in the air.

“Some friends said this is what it did the last time the big eruption happened in 1995/96. There's a lot of steam coming out and the occasional smell of sulphur in the air, so there’s definitely something happening.”

Bremner said the locals were all quite pragmatic about the situation, telling her it was okay, as long as it didn’t affect the ski season.

“Of course we don’t know what it’s going to do, but it is unsual and there’s a lot of steam up there today.”

An image from a GNS webcam shows steam rising from Mt Ruapehu on Tuesday.

She said she had an emergency bag packed, had bottled extra water, and had stocked up on dog food for the pets.

GNS Science duty volcanologist Geoff Kilgour said the first sign of the plume occurred at 9.45am and it ascended slowly to around 1.5km above the summit.

“No seismic or acoustic activity accompanied the plume appearance, indicating the steam plume was not generated by strong activity in the lake,' he said.

“We cannot rule out that very minor activity has occurred, which is why our scientists conducted an observation flight early this afternoon.

“Observations from that visit indicate that central vent continues to be actively upwelling, and the lake level is marginally higher.”

Kilgour said the lake temperature is now around 39C.

“In the past, lake temperatures this high, combined with cool and calm atmospheric conditions, have generated visible steam plumes above the lake.

“We may expect more plumes to be seen over the coming weeks/months under suitable weather conditions.”

He said analysis of the latest crater lake fluid samples were similar to past analyses and showed no clear indication that magma was interacting with the hydrothermal system beneath the lake.

“We will conduct further gas measurement and observation flights as weather conditions allow.

“Mt Ruapehu is an active volcano and has the potential to erupt with little or no warning when in a state of elevated volcanic unrest.”

National Park Four Square and Gas owner Dhruv Dewan said the mountain does it’s own thing and there’s nothing anyone could do about it.

“To put it in perspective, it is an almighty mountian, I am but a human, it’s going to do what it’s going to do and I’ll have to live with it.

“If it does go up we’ll get a lot more journalists down here needing some gas … and it will definitely put National Park on the map.

“There’s no such thing as bad publicity,” Dewan said.

For information about responding to volcanic activity there are guidelines from the National Emergency Management Agency's Get Ready website.