Volcanoes

Volcanoes are New Zealand’s landscape

Aotearoa New Zealand sits across the boundary between the Pacific and Australian tectonic plates, which is part of the ‘Pacific Ring of Fire’. This boundary is defined by the Hikurangi Trough off the east coast of the North Island and marks where the Pacific Plate descends under the Australian Plate. The volcanoes in New Zealand are fed by molten material (magma) produced by this process. Magmas are generated by a mix of partial melting of material from the Pacific Plate and the Australian Plate. These magma bodies accumulate and feed the active volcanoes above them.

Our volcanoes are world renowned, both in frequency of eruptions and volumes of material ejected. Familiar to the public, they dot the landscape of the North Island and extend in a line under the ocean along the Kermadec Ridge north-east towards Raoul Island and beyond. Today, many of these volcanoes are classed as active while some of the older ones are extinct. The time between eruptions can range from a few years to over a thousand years.

At GNS Science, we study extinct and active volcanoes to better understand what is happening in our dynamic landscape. Our research has applications in volcanology, preparedness, emergency response and community resilience.

Studying the past and present

Studying extinct and active volcanoes gives us insight into our volcanic past, present and future.

To look into the wonders of our volcanic environment our researchers:

Use radioactive isotopes to date eruptions
Link rocks to past eruptions to see how far material travelled
Conduct geochemical analyses of material expelled to understand the state of the magma system driving the volcano when it erupted
Examine the material from a particular site for clues to the duration, magnitude and length of each phase of an eruption

We also monitor present conditions of New Zealand’s active volcanoes by:

Visual observations
Chemical analyses
Seismic and acoustic monitoring
Ground deformation assessments

Data from monitoring of our volcanoes is fed into GeoNet. The volcano monitoring team gauge the present state of our active volcanoes and communicate this through the NZ Volcanic Alert Level system and through direct communication with stakeholders, responding agencies, infrastructure providers and the public.

Alert level raised at Taupō Volcano - 20 September 2022 transcript

In Aotearoa New Zealand, we use a volcanic alert level system to describe how active volcanoes are.

Volcanic alert level one means minor unrest. And in the volcanic alert level system, it is the lowest level of unrest at a given volcano.

Lake Taupō, until very recently was at volcanic alert level zero. So why are we changing the volcanic alert level to one at Lake Taupō?

One of the key things is over the past few years, we've really started to understand better what volcanic alert level one means at Lake Taupō Volcano, and with the current level of activity that we've recorded, the earthquakes and the ground deformation, we feel it is appropriate to set the alert level at one.

Behind me is Lake Taupō, and when we mention Lake Taupō, people think about very very large eruptions. There has been some large eruptions, like 30,000 years ago that created a huge crater now filled with this lake.

And then later on, 1800 years ago, another big eruption created another of those calderas inside the bigger one. But the reality is that the vast majority of the eruptions at Lake Taupō are actually quite small.

Over the last 29 eruptions, only two of them were actually large. All the other eruptions were very small size, probably similar to what happened to Ruapehu in 1995, 1996.

Lake Taupō, like most large volcanoes go through some quiet periods and periods with a bit more unrest. When we've got those periods of unrest, we start to see more symptoms.

At the surface, we see some earthquakes. We also see the ground deforming slightly. Not something that people can usually see, but something that we can measure with our monitoring network.

Since May 2022, we have recorded about 600 earthquakes in the lake area. Some of them were actually big enough to be felt by people. The vast majority of those earthquakes were actually quite small and wouldn't be felt, but they would be recorded by our instrumentation.

So remember, if in the future you feel one of those, drop, cover and hold. In addition to being a large volcano,

Lake Taupō is also crossed by a number of really big faults which are crossing the whole region, what we call the Taupō Volcanic Zones. And when we do have earthquakes occurring inside the lake, they are either occurring
along some of those faults or they are occurring around the body of magma, those molten rocks that we know exist under the surface at depths since the last eruption.

So a key thing for us as we try to understand what those earthquakes actually mean during those periods of earthquakes, is to try to understand where they occur and what process they actually related to.

And we keep monitoring the volcano and we will keep you updated on the activity.

Applications for research

Studying volcanoes and past eruptions provide valuable insight into the timing, size and extent of past eruptions. This provides useful information for predicting and modelling future eruptions. These models inform our predictions of when an eruption may occur happen and how much damage it may cause.
Modelling is also used for creating hazard scenarios. If we can predict the timing, location, size and eruption style of a given volcano, we can predict hazards associated with it. These hazard scenarios are useful for emergencies services, lifeline groups and communities living near our active volcanoes for planning a response.
Mātauranga Maori

Māori oral history records may provide insight into eruptions of the recent past and into changes noted in the pre-eruption landscape. We work with Māori practitioners to provide a more holistic understanding of the behaviour of our maunga. Mātauranga Māori also informs the development of useful, culturally relevant disaster management plans and recovery plans that ensure mana whenua are supported through recovery and in developing resilience.