Air vision from polynesian islands of Tonga.

Robot boat maps underwater volcano in South Pacific

Image credit: Air | Dreamstime

A robot boat, remotely controlled from the UK, has returned from an initial survey of an underwater volcano in Tonga that erupted explosively back in January.

The Uncrewed Surface Vessel (USV) Maxlimer is part way through mapping the opening, or caldera, of the submarine Hunga-Tonga Hunga-Ha’apai (HTHH) volcano in the South Pacific.

The boat was developed by British company Sea-Kit International and is part of the second phase of the Tonga Eruption Seabed Mapping Project (TESMaP), led by New Zealand’s National Institute of Water and Atmospheric Research (Niwa) and funded by the Nippon Foundation of Japan.

Data collected from the USV so far has confirmed earlier reports of continuing volcanic activity from HTHH. A winch on the boat allows instruments to be deployed at depths, reaching 300m, to collect data from the entire water column.

The boat is gradually building up an elevation map of the volcano's opening, or caldera

The boat is gradually building up an elevation map of the volcano’s opening, or caldera.

Image credit: SEA-KIT/NIWA/Nippon Foundation/SEABED2030

The 12m-long Maxlimer is being remotely controlled approximately 10,000 miles away from Tonga in the small coastal village of Tollesbury in Essex, via a satellite link.

In a control room in Sea-Kit’s headquarters, several large screens display live feed images from the 10 cameras on board Maxlimer. Operators watch on as real-time data gets beamed in from the South Pacific.

Ashley Skett, director of operations at Sea-Kit, said that the operators can communicate with other vessels in the area via radio: “We have designed the boat from the ground up to be remotely controlled and remotely operated. So, every switch, every function on the boat, every light, we can control from here."

Equipment on USV Maxlimer

Image credit: BBC

Experts believe robotic, remotely controlled boats are likely to be the future of maritime operations. When surveying a dangerous area such as the active HTHH volcano, remote control ensures that no human crew are put in harm’s way.

The Sea-Kit team added that, as there is no crew onboard, the vessel can be much smaller, leading to reduced carbon dioxide emissions. “We use five per cent of the fuel that an equivalent manned vessel doing the same job that we’re going now would use,” Skett said.

The eruption of the HTHH on January 15 2022 created waves that reverberated around the Earth and reached 100km into the ionosphere. It also triggered a massive tsunami that spread across the Pacific Ocean and the atmospheric shockwave caused by the eruption was felt as far away as the UK.

When not at sea, Maxlimer is moored at Nuku'alofa on Tongatapu, Tonga's main island

When not at sea, Maxlimer is moored at Nuku’alofa on Tongatapu, Tonga’s main island.

Image credit: SEA-KIT/NIWA/Nippon Foundation/SEABED2030

The team is currently waiting for rough weather to pass through the region before taking the Maxlimer back out to the underwater volcano to fill in the remaining gaps in its map of the caldera.

Data collected from the USV will help the researchers gain a better understanding of why the eruption had such a huge and violent impact. They also hope the data will also help predict future eruptions.

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