Deep-sea eruption ‘goldmine’

Scientists have shed new light on a powerful undersea eruption north of New Zealand that proved larger than any on land in the past century.

In a just-published study, researchers have analysed the 2012 eruption of the seafloor Havre volcano, which lies in the Kermadec Islands, about 1000km off the North Island.

The largest deep-ocean blow of the past century was revealed when satellite imagery picked up pumice spread across 400sq km of ocean.

“We knew it was a largescale eruption, approximately equivalent to the biggest eruption we’ve seen on land in the 20th century,” said the study’s lead author, University of Tasmania volcanologist Dr Rebecca Carey.

“This event is a scientific goldmine as for the first time there are quantitative constraints on submarine eruption dynamics, and the role of the ocean in modulating those dynamics.”

The volcano had been discovered only a decade earlier.

With 80 per cent of Earth’s volcanoes on the seafloor, the study of submarine volcanism was “very important”, said Carey, who worked alongside Otago University’s Professor James White on the study.

Volcanism was also an important source of heat and chemicals to the ocean, and supported life.

Over the two-year study, researchers used submersibles to map, observe and collect samples from Havre.

“This is the first event of high silica magma composition where we are able to provide the constraints that test whether the hydrostatic pressure [ the pressure from the ocean above] did suppress explosivity,” Carey said.

“We were able to demonstrate that the eruption was very complex, involving more than 14 aligned vents that represent a massive rupture of the volcanic edifice.”

Carey said data collected for the study has also led to much interest from the broader scientific community.

“The eruption blanketed the volcano with ash and pumice and devastated the biological communities. Biologists are very interested to learn more about how species recolonise, and where those new species are coming from,” she said.

“There is a decade worth of interdisciplinary science to do based on our 2015 voyage data and samples,” she said.

“It’s very exciting to marry the geosciences with other scientific disciplines addressing novel research questions.”

The study was published online in the journal Science Advances.