New Volcanic Futures

Mt Taranaki eruption could knock out power to entire region

by Robin Martin, RNZ, Reporter

Contrary to popular opinion, Mt Taranaki is neither extinct or dormant, but an active volcano with a 50 percent chance of erupting in the next 50 years.

The view of Mt Taranaki reflected in the tarns on the Pouakai saddle. Photo: RNZ / Robin Martin

New modelling has revealed a significant eruption could knock out power to the entire region.

Mt Taranaki is believed to last have erupted more than 200 years ago.


Photo: Supplied

University of Canterbury professor in disaster risk and resilience Tom Wilson reckons the next time it erupts it could be severe.

“Given that the last eruption was we think back in the 1700s about 1760-ish, we think. It possible means there’s been a recharge of the magma chamber and the next eruption is going to be a little bit bigger or on the bigger side of what Taranaki can produce,” Wilson said.

Wilson has been working alongside PhD student Alana Weir to examine the risks posed to the region as part of a study called Transitioning Taranaki to a Volcanic Future.

It is focused on the disruption to the economy, infrastructure and the road to recovery after an eruption.

Photo: Supplied

Taranaki Civil Defence regional manager Craig Campbell-Smart said there was there was a good understanding of the immediate threats to life during an eruption such as falling rocks, deadly pyroclastic flows volcanic mudflows or lahars and the study had brought into focus secondary hazards.

He was also worried about electricity supply.

“That’s the key lifeline asset for us that could be taken out by an accumulation of ash fall and so that’s a really important work to focus on building resilience into that asset, and the asset owner Transpower and the lines company Powerco I’m sure will be looking to invest more strongly into the future but also to understand the vulnerability that they have at the moment.”

What does the public know?

On the streets of New Plymouth there was mixed understanding of how likely an eruption on Mt Taranaki was.

Joe reckoned any threat was a while off.

“I’ve heard it has a major eruption once every hundred thousand years or something like that.”

Helen was expecting anything untoward.

“We were told it was dormant at school, yeah, we were told it was dormant growing up.”

Blair had heard something similar.

“I thought the mountain was asleep but could wake up at anytime.”

Photo: Supplied / Taranaki Civil Defence and Emergency Management

“The length of time from the last eruption is long and we’ve just lived and grown up in this region without experiencing those eruptive events so that’s quite a bit of history to re-tell and that’s a challenge, but I think it is a really important one.”

He wanted everyone to do their bit by making sure they had three days’ drinking water and a week’s worth of food at home so they could care for their own immediate needs in the case of an eruption.

In a statement, Transpower said all its overhead electrical networks – both transmission and distribution – were susceptible to volcanic activity.

The State-owned enterprise said although there was no specific workaround that would guarantee supply to Taranaki in the case of an eruption, it did have diversity of supply to the region with transmission lines coming from both the north and south.

Transpower said it continued to work with researchers – including those at GNS and the University of Canterbury – to monitor and understand changes to probability or consequence models across all hazards that could impact the its network.