A new volcano warning system - which would have alerted people to the Whakaari/White Island eruption 16 hours before it happened - is ready to be made operational.
A view of Whakaari/White Island from the air as a helicopter approaches. Photo: Supplied/Auckland Rescue Helicopter Trust
The warning system, developed by a team of scientists at Auckland University, is thought to be the first of its kind anywhere in the world.
For the past decade, scientists have been monitoring seismic signals including vibrations in the earth - at Whakaari/White Island.
Over the 10 years, there have been five eruptions, including the eruption last December which led to the deaths of 21 people.
University of Auckland senior lecturer Dr David Dempsey is one of the researchers behind the new warning system.
He said they've developed an algorithm which can pick up patterns in the seismic activity before the eruption happens.
"In particular, there is a four-hour burst of seismic energy, that seems to occur hours or days before an eruption," Dr Dempsey said.
"If you can pick that up in real time, then that then serves as the basis of an early warning system."
The team compiled the data collected before December's eruption, and ran it through their system.
"For last year's eruption, there was the four hour burst started about 17 hours before that eruption.
"So the early warning system that we had developed, when it was shown that data, it issued an alert 16 hours beforehand."
As far as he's aware, nothing like this is being used in the world.
Volcanologist Professor Shane Cronin, who worked on the system, told Morning Report it would have almost certainly have made a difference at Whakaari/White Island.
"Each time there's an alert there's something like an 8.5 percent chance of eruption."
- "There's a bit of a black hole where warnings are issued and how they're acted upon"- Shane Cronin
Warning system not 100 percent reliable
Geoff Hopkins visited the volcanic island on 9 December, and was returning to Whakatāne when the eruption happened.
He said his expectations arriving on the island in the morning was that everything was being checked.
"My experience at Whakaari was that we knew it was a highly monitored volcano, yet that gave you a false sense of security, because it felt like it was being monitored, yet none of that information at that current stage was able to predict that eruption."
A damaged helicopter is seen on White Island after the eruption. Photo: Instagram/The Helicopter Page
The warning system is not 100 percent reliable - out of the five eruptions over the past 10 years at Whakaari, it would have picked up four.
But even with that ratio, such a system would help tour operators make calls on whether to proceed or not.
Whakatāne Mayor Judy Turner wants tours to resume at Whakaari, but in a much more restricted way.
"Depending on the level of seismic activity is whether you just stayed on the boat and sailed around, whether you could land on the island, but not go up to the crater, or whether on some occasions it may even be appropriate to go up to the crater as has been the norm."
She said the new warning system would help reassure tourists and operators.
Ruapehu and Tongariro next to be looked at
Scientists are now looking to see whether the warning system will work for other high-risk volcanoes, such as Ruapehu, or Tongariro.
Because it can be triggered without a subsequent eruption there will be times when tourism businesses will have to close unnecessarily - the scientists estimate for about a month a year on average.
The White Island Tour operators rescue people from the island, just after the eruption. Photo: Supplied / Michael Schade
Ruapehu District Council destination manager Warren Furner said businesses will need to be convinced introducing it would be a plus not a minus.
"The risk that that places on small to medium enterprises particularly, around Ruapehu, where a lot of tourism-support businesses are vulnerable, to even small impacts on their income.
"So there's quite a lot of work to do in that space in terms of some of the consequences."
The Auckland University researchers said they were now in talks with GNS Science to get the system operational.
Dr Dempsey said he hoped it could then be picked up around the world.
GNS Science volcanologist Nico Fournier said while the warning system was promising, there was still some way to go before it was operational.
He said more research was needed before it was deployed.