THREE KEY FACTS: 

• Rivers of lava could flow for kilometres through Auckland if an eruption occurred within the large and young volcanic field beneath the city. 
• New Zealand scientists recently visited the Spanish island of La Palma, where an 85-day eruption damaged hundreds of homes in 2021, to learn lessons for Auckland. 
• Among other insights, they found that lava flows could pose a major fire risk for Auckland’s many timber-frame buildings. 

An Auckland eruption would likely send slow-moving rivers of lava flowing through the city – so scientists have been looking for lessons from a recent disaster in Spain’s Canary Islands. 

While its 53 volcanoes are considered unlikely to erupt again, the Auckland Volcanic Field is geologically young, potentially active, and could unleash fast-moving surges of gas, widespread ashfall – and lava bombs and flows. 

“With the type of volcanoes we have in Auckland, we can almost certainly expect to see lava flowing for hundreds of metres to several kilometres from [the volcano] vent,” GNS Science volcanologist Dr Geoff Kilgour said. 

Kilgour recently led a research trip to the island of La Palma, where an 85-day eruption released more than 160 million cubic metres of lava that measured 70m thick in some parts. 

The scale of destruction there was “hard to imagine”, he said. 

Damage from an 85-day eruption in 2021 on La Palma, in Spain's Canary Islands, amounted to more than $1.5 billion. Photo / GNS Science 

“Thick rivers of lava flowed through populated areas towards the sea, burying hundreds of houses,” he said. 

“We spoke to Canarians who lost their homes and have had to relocate, and others whose health is suffering because they continue to live in damaged homes they can’t afford to repair.” 

The team found it would be important to carry out on-the-ground damage assessments as soon as possible after an eruption, rather than rely on remote methods such as via satellite. 

They also observed how lava ignited fires as it flowed: insights they would use to inform models for Auckland. 

“We expect fires to be a big issue in Auckland, where we have many more timber-frame buildings, and our volcanoes produce similarly hot and fluid lava.” 

Kilgour expected there would be similar engineering challenges with rebuilding critical infrastructure. 

“Layers of cooling, but still very hot lava means nothing heat-sensitive can be built directly on or below ground.” 

Researchers on a GNS Science-led trip assess one of hundreds of homes destroyed in an 85-day eruption in 2021 on La Palma, in Spain's Canary Islands. Photo / GNS Science 

Dr Jo Horrocks of the Natural Hazards Commission (NHC) Toka Tū Ake, which funded the research, said the findings would be useful for planning and modelling. 

Although the everyday chances of a major eruption in New Zealand were low – the commission last dealt with eruption-related claims after Mt Ruapehu’s blow three decades ago – the damage caused by an Auckland event would be “significant”. 

Previous modelling has indicated the economic fallout from impacts on the city’s commercial and industrial sectors alone could stretch into the tens of billions. 

“As we saw in La Palma, given the monumental impact that a volcanic eruption could have on people and property, it’s important to be prepared,” Horrocks said. 

Jamie Morton is a specialist in science and environmental reporting. He joined the Herald in 2011 and writes about everything from conservation and climate change to natural hazards and new technology.