A robot boat maps an underwater volcano in the South Pacific

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

The Unmanned Surface Vessel (USV) Maxlimer is 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 Seafloor Mapping Project (TESMaP), led by New Zealand’s National Institute of Earthquake Research. and the Atmosphere (Niwa) and funded by the Nippon Foundation of Japan.

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

The boat gradually constructs an elevation map of the opening of the volcano, or caldera.

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

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

In a control room at Sea-Kit headquarters, several large screens display live images from the 10 cameras on board the Maxlimer. Operators monitor real-time data transmitted from the South Pacific.

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


Equipment on the Maxlimer USV

Image credit: BBC

Experts believe remote-controlled robotic boats are likely to be the future of maritime operations. When surveying a dangerous area such as the active volcano HTHH, the remote control ensures that no human crew are endangered.

The Sea-Kit team added that since there is no crew on board, the vessel can be much smaller, which reduces carbon dioxide emissions. “We’re using five percent of the fuel that an equivalent manned ship doing the same job as the one we’re going to now would use,” Skett said.

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


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

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

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

The team is currently waiting for bad weather to pass through the area before returning the Maxlimer to the submarine volcano to fill in the remaining gaps in its caldera map.

Data collected from the USV will help researchers better understand 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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