A team of NIWA scientists has arrived in Tonga to explore why Hunga Tonga–Hunga Ha'apai erupted the way it did.
Three months after the devastating eruption, a group of 15 scientists are on a mission to study its underwater impacts.
It's hoped the research will help them better understand what happened during the blast and how communities can better prepare for any future eruptions.
The NIWA scientists will survey thousands of square kilometres of the seafloor from their vessel, RV Tangaroa, and collect video images of the eruption's impact.
"It's something that was not expected for this sort of volcano", says voyage leader Kevin Mackay. "So the evidence about what actually happened, about why it was so violent, actually exists on the seafloor, so we are going to investigate by mapping the ocean bed."
They'll be using sonar technology to measure how different the underwater landscape is.
Mackay says they'll also be investigating other changes around the volcano.
"In terms of water quality and chemistry, the type of seafloor, the type of sediment there is, and actually see what life exists, if any at all."
The NIWA-Nippon Foundation Tonga Eruption Seabed Mapping Project is being funded by the Nippon Foundation, Japan's largest non-profit organisation.
"This research will let us really understand not only what happened on January 15 when this volcano erupted so violently, but help us understand the risks that occur to other communities that are near volcanoes just like this," Mackay says. "These volcanoes occur all around the Pacific Ring of Fire, including places like New Zealand and Japan."
It comes after Auckland University volcanologist Professor Shane Cronin snorkelled over the volcano.
He's been collecting ash samples around Tonga, studying the effects of the eruption.