Modern monitoring systems watch Ruapehu around the clock, providing information in real time that simply wasn’t available when the volcano erupted in 1995.
Scientists say that means New Zealand is far better equipped to detect the warning signs, manage the risks and respond to a future event than it was during the dramatic 1995-96 eruptions.
Advances in monitoring technology mean volcanologists have a much clearer picture of what is happening inside and beneath the mountain than they did three decades ago, and improved hazard modelling and emergency management procedures are in place.
“We’ve done a lot of planning over the last 30 years,” says Geoff Kilgour, chief scientist of Volcanic Hazards at Earth Sciences NZ.
“We’ve got the 24/7 (monitoring) centre, we’ve got on-call volcanologists, and we’ve even got on-call people above them. I think we’re just so much better prepared. We’ve got our procedures in place – we’re ready.”
Scientists, Civil Defence and emergency managers, and iwi representatives gathered at Maungarongo Marae in Ohakune on 19 June to mark 30 years since the eruptions and to reflect on what was learned.
“Thirty years ago, we had a sparse network of sensors, and a couple of those were seismometers, detecting earthquakes. We might have had three or four in the national park. Now we have about eight, and we have a lot of other different sensors,” Kilgour said.
In the 90s, there were occasional field visits to survey for ground deformation and take samples.
Volcanologist Graham Leonard, general manager of the Geological Hazards Science Mission at Earth Sciences, said the work was “completely different” today.
“We’ve got so many more data streams and in different places, and they come through live.”
Advances included real-time monitoring, satellite deformation data, gas sensors, automated earthquake detection and alert systems when activity is building.
“We’re in a better position than we were 30 years ago,” Richard Smith, director of the collaborative national Natural Hazards and Resilience research programme Te Pae Turoa, says.
“One of the challenges with volcanoes is that it’s all happening underground until it isn’t, and so it’s really hard to know in detail and to measure is difficult.
“A lot of the advances are the various new technologies that enable us to look underground and work out what’s going on.
“There’s a whole new way of being able to detect and track what is happening, and so we’re getting much more information.”
Smith said the challenge is bringing that information together and communicating it effectively.
“There’s still a need for a lot of work on bringing together a message that resonates with the community, so they can understand what are the actions that we can take based on that information.”
Former Department of Conservation scientist Harry Keys recalled the hindrance of “slow communications” in 1995.
“It was so difficult compared with now. In those days we had smart faxes – you put a whole lot of addresses in. I remember doing that after meetings. We’d be at it for hours to get all the information out.”
Deanna Wilson, who heads Ngāti Rangi’s environment and cultural development team, says iwi involvement is vital in helping the community prepare for and respond to eruption.
“It’s important for everyone’s safety, ours as well, because I know that many of us would not move – a bit like Pompeii – because of our belief in and our connection to our maunga. But we have to be mindful of taking on the benefits of both the western science and what we believe to be true.”
The 30-year commemoration brought together a group that has been gathering every decade since the eruptions to look at the science evolving to help the country understand how best to live with volcanic activity.
Smith said part of the reason for bringing this group back together is to keep awareness alive.
“Awareness is important in preparing for the next event.”
Smith said the tragedy at Whakaari, which killed 22 people, remained front of mind. A key focus was helping communities understand the risks associated with volcanic environments and how those risks can be managed to avoid further loss of life.
In the meantime, scientists are using their new technology to watch for signs of future eruptions.
“We’re tracking for magmas rising toward the surface,” Kilgour said. “When that happens, it generates earthquakes and there’s different gases that we can detect at the surface, monitoring in near real-time.”
Ground sensors and satellites can also detect whether the ground is inflating or doming, tracking movement at very small scale – “by several millimetres up or to the side”.
How likely is another eruption?
Leonard says the basis for anticipating a future eruption is mostly the past.
“We’re lucky we’ve got quite a good historical record here for the last 100 or 200 years, and before that through mana whenua.
“That gives us a feeling for the tempo of the frequent smaller eruptions.
“For bigger eruptions, we look to the geological past – understanding the rocks and the ash lying in the landscape and making the volcano, and finding out when they erupted.”
Leonard says Ruapehu remains one of the country’s most active volcanoes and there is “a decent chance” of an eruption in any decade, with larger eruptions like those in 1995-96 every 50 to 100 years.
Very large eruptions – “the really big ones, the ones we haven’t seen in human history” – were much rarer: once every thousand, 2000 or 3000 years.
There is no recorded history of a Ruapehu lava eruption, although the volcano is built from lava.
“It’s been very dominated by ash coming out through the summit lake, but there’ll be future lava eruptions,” Smith says.
“It is still an active system, and it’s got a long history going back hundreds of thousands of years. It’s a big volcano – and it’s still got plenty of life.
“Ruapehu will erupt again.”
LDR is local body journalism co-funded by RNZ and NZ On Air
