Direct ocean measurements aim to fill gaps in understanding the Hunga Tonga-Hunga Ha’apai eruption

SeaKit engineer on the dock in Tonga mounting the PMEL MAPRs onto a specifically designed cage to fit on the USV Maxlimer. Credit: Sea-Kit International/NIWA/Nippon Foundation

PMEL's Sharon Walker joined a team of engineers, multibeam mapping experts, and scientists from around the globe to complete a high-resolution bathymetric and hydrothermal plume survey of the post-eruption caldera at the Hunga Tonga-Hunga Ha’apai (HTHH) volcano. This is the first time a survey that includes direct measurements of the water column up to 300 meters deep has been conducted entirely remotely using an uncrewed surface vessel operated and monitored by engineers and scientists who are located across the globe.

As part of the Tonga Eruption Seabed Mapping Project (TESMaP), PMEL provided Miniature Autonomous Plume Recorder (MAPR) instruments to determine the level of ongoing volcanic and hydrothermal activity within the caldera. A winch and custom built frame were added to the uncrewed surface vessel (USV) Maxlimer from Sea-Kit International Ltd to house and deploy the MAPRs and a small CTD. To date, 24 vertical casts and 9 tow-yo’s have been successfully completed. The USV Maxlimer is also equipped with a multibeam echo sounder to acoustically measure depth and state of the seabed. 

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