TURN TO PAGE 2 Preparing Taranaki for eruption possibilities
When Taranaki Maunga blows, a large eruption could leave about 27,000 homes without electricity for five months and about 13,000 homes without water for more than three months.
And when it begins erupting, there’s a chance it could continue erupting for a lifetime, decimating the region’s economy and transport routes and making life in Taranaki radically different for generations.
Whether the community is ready for such an event has been the question addressed by a five-year, $13.7 million study of possible eruption scenarios.
The project, funded by the Ministry of Business, Innovation and Eduction (MBIE), involved risk management organisations working alongside scientists on possible post-eruption scenarios and the region’s readiness.
The research put the likelihood of a Taranaki Maunga volcanic eruption happening in the next 50 years at between 30% and 50%.
Tom Wilson, a professor of disaster risk at the University of Canterbury, said communities in the Taranaki region might have to learn to live with eruptions.
“It could be that you look at your weather forecast and you also look at the ash forecast,” he said.
“Do I hang my washing today because we are likely to get ashfall?”
There were communities around the world, such as the people living around the Sakurajima volcano in Japan or under La Soufrière, a volcano in Saint Vincent and the Grenadines, that had learnt through severe challenges to deal with eruptions, he said.
Wilson, who is also the National Emergency Management Agency’s chief science adviser, said the project, Transitioning Taranaki to a Volcanic Future, focused on post-eruption planning.
Many would lose water supplies and access to electricity and would be isolated because of lahars (volcanic mud flow) destroying bridges and flooding roads, he said.
“We’d want to be making sure that we’ve got a good evacuation process.
“It’s a scary prospect, you know – leaving your home for an unknown period of time is really scary.”
But the loss of an essential service such as electricity because of ashfall could be prevented by the development of offshore wind farms and moving the electricity cables underground, he said.
Market Economics Research director Nicola McDonald said one of the scenarios showed a large-scale eruption, involving two periods of eruption each lasting about one month, with a quiet period in the middle of two to three months’ duration.
Impacts would be disproportionate over New Zealand, she said.
The Taranaki region, for example, could lose about 50% of its gross domestic product in the first eight months. For the country as a whole, the loss would be 1.3% of GDP.
McDonald, who studied the economic impact the eruption would have, said the loss would be about $5.1 billion after two years.
“It is important that people can take actions to mitigate or reduce the economic consequences of an event.”
That would include interventions to make the electricity and water supplies more robust, she said.
“Each of these interventions could reduce the losses in GDP over two years by around $0.5b to $0.6b.”
As the result of a large eruption, about 27,000 homes would be without electricity for more than 150 days and about 13,000 homes would be without water for more than 100 days.
It was research figures like this that University of Auckland professor of volcanology Shane Cronin said were aimed at moving people from a state of relaxation about a future eruption to a state of awareness.
“One day when it does erupt, or when it begins to erupt, then it will probably remain a threat for a lifetime,” he said.
The research project received $13.7m in funding from MBIE in 2019 and will end this year.
Researchers from Canterbury, Lincoln, Otago and Massey universities have taken part, as have research centres and universities in Colombia, Germany, Italy, Mexico and the United States.
Cronin said they have been collecting geological evidence, such as samples of ash layers, that documented the past 30,000 years of Taranaki volcanic activity.
The team had been working on environmental archives in the Auckland and Waikato regions – “and even across as far as Hawke’s Bay”.
There have been quiet patches without eruptions of between 100 and 200 years, he said, but also high-activity patches.
Cronin, who led the research, said that in the past 2000 years, 20 to 22 eruptions had occurred – which meant one eruption every 90 to 100 years on average.
The last documented eruption was in 1790, he said.
Statistical data suggested the next volcanic eruption in Taranaki was overdue.
“We’ve been doing a lot of in-detail geochemistry and geophysical work to try to understand: how would we recognise the volcano is warming up?”
Their last expedition on Taranaki Maunga in January, which involved Italian scientists from Bari and Bologna universities,
was aimed at discovering the first materials that erupted during individual eruptions.
“We were looking at the very, very, very first ash that was produced by each eruption,” he said.
From the materials they could understand how the volcano reacted each time. “That kind of starting-off of the eruption gives us an idea of what might happen next,” Cronin said.
Taranaki has been a “dormant beast”, but things could change fast, he said.
The next volcanic eruption in Taranaki could go on for decades, as it had happened previously.
“Once things move into an active cycle, then the volcano is a very different beast to live around than it has been for the past 200 years.”
That future eruption could trigger irreversible changes, at least in a generational perspective, he said.
Rather than publishing a research paper at the end of the project, Cronin said, the group had been holding meetings every six months to inform people about the results and working with local authorities to provide tools to cope with the eruption.
Part of the research involved the introduction of a new monitoring approach.
“We’ve identified new warm springs that are surrounding the volcanoes, and we’ve developed a new monitoring approach based on those warm springs,” he said.
Some volcanic springs were warm and some were cold, Cronin said.
The study of these volcanic waters was undertaken by New Plymouth-based volcanologist Cindy Werner.
Werner said she has been working in collaboration with all the iwi in the region, but mostly Te Ātiawa and Ngāruahine.
The springs were sacred for the iwi, she said.
“There are several sets – there is some on the flanks of the volcano and some on the ring plain, so outside the national park,” she said.
Werner said the geochemical monitoring of the springs could be used for forecasting the next eruption.
As part of the research project, GNS Science, a Crown research institute, has put a monitoring station on the mountain’s west side.
She said it was the first real-time monitoring station in Taranaki measuring the temperature of the spring water.
“The work is ongoing; it’s not finished yet,” Werner said.