Little-known eruption near NZ the biggest in 100 years

Scientists studying a little-known volcano off the coast of New Zealand now believe its 2012 eruption was one of the biggest the world has seen in the last 100 years.

The Havre volcano, on the floor of the Pacific Ocean about 1000km northeast of the North Island, was only discovered in 2002. Its 2012 eruption went unnoticed until a Kiwi woman saw something strange while flying home from Samoa.

Havre volcano
Location of the eruption. Photo credit: Supplied

"I took a couple of pictures, wondering if it was an algal bloom, oil spill or, recalling a conversation with a friend the week before, a deposit from a volcano," artist Maggie de Grauw told the Waikato Times in 2013.

A week later, the massive deposit of ash and pumice was found by an Air Force Orion crew, and satellite imagery soon showed it was 480km long and about 50km wide - bigger than Israel.

Researchers from the University of Tasmania and around the world have spent the past two years investigating the eruption, and now think it was one to rival the biggest we've seen in recent history.

"We knew it was a large scale eruption, approximately equivalent to the biggest eruption we've seen on land in the 20th Century," said volcanologist Dr Rebecca Carey, who led the study.

"The eruption was very complex, involving more than 14 aligned vents that represent a massive rupture of the volcanic edifice."

Rebecca Carey.
Rebecca Carey. Photo credit: Supplied

The pumice - solidified lava filled with air bubbles - ended up on beaches across the Pacific, including New Zealand and Australia.

Ms de Grauw even found some herself six months later, which she turned into jewellery.

The eruption wasn't good news for local wildlife however, and Dr Carey says biologists are "very interested to learn more about how species recolonise, and where those new species are coming from".

"There is a decade worth of interdisciplinary science to do based on our 2015 voyage data and samples. It's very exciting to marry the geosciences with other scientific disciplines addressing novel research questions."

The study was published Thursday in journal Science Advances.