Bethany Rolston meets the 25-year-old Waikato volcanologist who has dedicated the last three years of his life to creating a 500km2 geological map of Mt Pirongia. His map - the key to uncovering the mountain's 2.5 million-year volcanic history - shows Pirongia's eruptive history was more explosive than previously recognised.
As a young boy, Oliver McLeod was fascinated with Mt Pirongia.
He remembers gazing up at the mountain while visiting the Waikato from Auckland, awestruck by its size, rugged terrain and mystery.
Two decades later he embarked on a journey to create a geological map of the mountain, which covers a level of detail like no other.
Pirongia is 20km west of Te Awamutu. The extinct volcano rises to 959m and is the highest peak in the Waikato region.
McLeod's map is the key to unlocking information about its 2.5 million-year history.
The three-year project is part of his PhD at the University of Waikato.
The 25-year-old has a Bachelor of Applied Geology from the University of Otago.
He pitched his idea about Pirongia as a PhD topic to the University, having heard rumours no one had studied it.
It was accepted, although he was warned the mapping could take 20 years. Oliver has taken less than three years.
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Magnificence of the maunga
McLeod says the early days of mapping Pirongia felt like scrambling around in the dark.
"The first time I stood up on one of the peaks I realised just how big the project was and shocked at how big the mountain was — the valleys are 300m deep and the peaks about 1km high."
"Anyone who's hiked on Pirongia knows that."
But he's come to know the extinct volcano like the back of his hand.
He mostly tramps alone, saying it's the best way to think clearly, traversing dense bush and steep terrain, gathering information and rocks.
"I've spent thousands of hours on the mountain — people joke that it's like my second wife," he says.
The work is intense, but the magnificence of the maunga keeps calling McLeod back.
"To not only hike the mountain, but to do high-quality field surveys was a challenge," he says.
"After a day of field work you almost can't walk. Your legs are like jelly."
He's had a couple of close calls — once becoming disoriented and another time almost getting hypothermia.
However, he always takes his personal locator beacon and is thankful to have never needed it.
McLeod has completed more than 50 separate field surveys — all by foot — often doing 12-hour days and carrying 20-40kg of rocks home.
He then needs a week or two to process and record the information before his next excursion.
Mapping the 'unmappable'
McLeod believes other volcanologists haven't mapped Mt Pirongia because it would be difficult and time-consuming.
Maps of the regional geology were produced in 1926, 1994 and compiled in 2005.
They define the extent of Pirongia's volcanic terrain — its outline — but give no details on the volcanic stratigraphy.
"There have been a handful of famous geologists come through Pirongia, including Ferdinand von Hochstetter in 1864," McLeod says.
"None have attempted to map Pirongia because it is covered in dense native bush. There are very few outcrops of rock, meaning you have to work a lot more to find the field data."
He says other mountains around New Zealand have often taken centre stage in volcanologist circles, while Pirongia has been overlooked.
"Pirongia is tucked between Auckland and Taupō, so most of the research funding goes to those fields.
"To me, this was the perfect opportunity to study it, because no-one else was."
A dying art
McLeod is a field scientist, who uses and admires traditional fieldwork methods.
His ground-based geological surveys map volcanic stratigraphy — the layers of rock and the processes that created them.
He relies on the simple field tools of a GPS, camera, field notebook, compass clinometer for measuring the orientation of rock and small magnifier, called a hand lens, for identifying rocks in the field.
He also uses a hammer — handmade by a local blacksmith for the project — to break hard basalt rocks.
McLeod says the method is a dying art and believes it's the best way to create a map.
"Nothing can replace the learning environment that nature provides," he says.
"For me to understand the landscape, I must be immersed in it."
He's using the same methods as generations of volcanologists before him, building on the maps they created.
One of his mentors is University of Waikato honorary fellow Roger Briggs.
Briggs dedicated much of his career to studying the Alexandra Volcanic Group, of which Pirongia is the largest volcano, and is regarded as an authority on the volcanic geology of Western Waikato.
Also involved is Dr Adrian Pittari, McLeod's chief supervisor who has facilitated the PhD study.
The Australian volcanologist specialises in large rhyolitic eruptions, has accompanied McLeod on the field and is actively involved in daily discussions about the project.
Dr Marco Brenna is also on the team. The University of Otago petrologist is a world expert in the interpretation of textures in volcanic rocks and their source zones in the earth's mantle. He provides insight into the processes by which Pirongia's basalts, which are incredibly rich with large crystals, came to be erupted in this part of the North Island.
McLeod's mapping has revealed new information about the previously poorly-understood mountain.
"The map marks a point in our relatively young scientific history of New Zealand volcanoes," he says.
"It provides a snapshot in time of our understanding of how volcanoes work, and how they are formed."
His map suggests Pirongia's eruptive history was more explosive than previously recognised.
It updates the interpretation of Pirongia as a shield-type volcano, to a complex stratovolcanic system with numerous overlapping eruptive centres.
McLeod hopes the map will endure as a record of the mountain's geology for future generations of geologists, who will expand on the research in decades or centuries to come.
"The point of producing a map is to create a document with some degree of permanence, as a way to preserve scientific discovery in a visual form."
He also believes the map will dramatically change the geoheritage value of Mt Pirongia.
He will present his map to the Geoscience Society of New Zealand, along with an accompanying book he has written, next month.
■ Closer to home, McLeod is the guest speaker at the Pirongia Heritage & Information Centre AGM, speaking about his exploration of and new findings about Mt Pirongia. The meeting at the Heritage Centre is on June 20 at 7.30pm, with McLeod speaking around 8pm. Those interested in local history, or who have a Pirongia connection, are invited to the event
A passion for Mt Ngauruhoe
Oliver McLeod's passion for Mt Pirongia isn't the first story we have told about a volcanologist with a passion for volcanic mountains.
We first met Te Awamutu's own volcanologist Dr Janine Krippner back in 2010 when she was visiting home during celebrations of the Centenary of Te Awamutu Brass.
Krippner was staying with her parents Gaynor and Peter Krippner.
Her mum is from our Twin Town Moree, and Krippner's grandfather Ted Newbery and aunties Jenny and Glenda were over for the occasion — so it was a real family get-together — but she found time to visit and hike on her mountain, Mount Ngauruhoe, with like-minded friends.
Krippner left Te Awamutu College at the end of 2003 to pursue her dream.
She says while at high school the seed of her interest in volcanoes was sown by teachers Wayne Carter and Bruce Taylor.
In fact she says when she undertook her thesis, her subject being Mt Ngauruhoe, it was a dream she had held since the age of 14.
When she was home in 2010, Krippner was working for Shell in Perth.
The year before she had completed her Master's in Volcanology at Waikato University, like McLeod also working with Roger Briggs.
Her job was seismic interpretation — studying seismic readings and identifying the likelihood of gas and oil.
In 2017 she completed her PhD, which focused on pyroclastic flows on Shiveluch volcano in Kamchatka, Russia, and the 1980 Mount St. Helens eruption.
Krippner is currently working at the Smithsonian Global Volcanism Program (GVP) located in the National Museum of Natural History in Washington D.C. as GVP Image Collection Curator and Outreach Specialist, piecing together global volcanic eruptions and their impacts using reports, satellite data and social media.
Krippner also works with eruption archive photographs and information to create volcanic hazards material to help educate the world on volcanic activity and how people can stay safe.
"I am a science communicator, where in the world of 24/7 online media and social media I work to improve how volcanology interacts with international media to increase accessibility to information on volcanic activity," she says. "This could mean the difference between life or death in an eruption.
"During a volcanic crises that makes the media, I work to ensure that people are getting accurate information and understand what that information means."
Krippner has been interviewed by media about 200 times in 21 months, recorded podcasts and made a documentary.
Looking at McLeod's work, Krippner says after growing up near Pirongia and imagining it erupting when she was a child growing up in Te Awamutu, it is wonderful to see such an extensive study done to understand the history of this extinct volcano.
"This is an impressive effort, especially with the vegetation on Pirongia."
"When volcanologists work on active volcanoes to understand what they might do and how they might affect local populations, this type of geology work is key to forecasting what those impacts might be.
"While Pirongia will not be erupting again, the more we know about volcanic activity in the past, the more we can help the 800 million people around the world who live within 100 km of a potentially active volcano."
Janine says McLeod's research is another important link in the chain of understanding how our country evolved, and appreciating what our active volcanoes can do in the future.