Seabed changes caused by the Tonga volcanic eruption


A survey conducted by New Zealand and UK vessels, led by the New Zealand National Institute for Water and Atmospheric Research (NIWA), was completed following the January 2022 eruption.

Hunga-Tonga Hunga-Ha’apai (HTHH) sent ash and water vapor halfway through space and generated tsunami waves across the world.

NIWA reported that researchers have now fully mapped the area around the Pacific Volcano and found that the seafloor was eroded and sculpted by violent debris flows for a distance of more than 80 km (50 miles).

Data collected indicated that at least 9.5 cubic kilometers of material was displaced during the catastrophic event. Two-thirds were ash and rock ejected through the volcanoopensknown scientifically as a caldera.

Marine geologist and Niwa project director Dr Kevin Mackay said the explosion can be compared to a shotgun blast in the sky, and some of this material went beyond the stratosphere. in the mesosphere (57 km altitude).

He also added that it was the highest recorded eruption column in history.

Although there was a huge displacement of matter, the volcanothe flank remained intact. However, the caldera is now 700 m deeper than before the eruption.

Other research evidence NIWA discover the pyroclastic flows following the eruption, which are currents made up of dense lava, volcanic ash and gas that can reach temperatures of 1,000°C and speeds of 700 km/h.

Survey work has followed flows that have even managed to ascend and cross elevations of several hundred meters, and pyroclastic flows have played a large role in the HTHH an event.

“This explains, for example, what caused the rupture of national and international communication cables, with the national cable now buried under 30m of eruptive material.”

NIWA also pointed out the dramatic effects caused to the ecosystems of the region, due to the significant remodeling of the seabed. There were few signs of animal life on the volcano’s flanks, in the deeper water channels, and on most of the surrounding seafloor.

However, there were patches of abundant life that had survived the eruption on several seamounts, giving hope for recovery.

Taaniela Kula of Tonga Geological Services said: “Wehave always underestimated underwater volcanoes, and that there are five more just around Tongatapu so clearly there is a more urgent need for planning.

The study was carried out by the Tonga Eruption Seabed Mapping Project (TESMAP) and New ZealandResearch Vessel (VR) Tangaroa.

TESMaP was funded by the Nippon Foundation of Japan and organized with the help of Seabed2030, which is an international effort to properly map the Earththe bottom of the ocean.


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