Scientists have now mapped the seafloor around the Hunga Tonga-Hunga Ha‘apai volcano, and as a result we have learned just how massive the January 2022 eruption was. By comparing their soundings with 2017 data, they determined that at least 9.5 km3 of material was discharged. Debris was found 80 km from the volcano, and the volcano’s caldera has been replaced by a cavern 850 m deep. More from the NIWA media release and from ABC (Australia).
A storymap from Esri’s Robert Waterman, based on Maxar satellite imagery, shows the rise and fall of Hunga Tonga and Hunga Ha‘apai from being two separate islands before a 2015 eruption combined them, through its time as an apparently stable but awkwardly compound-named single island until it got blown apart last month.
The digital elevation maps above and below show the dramatic changes at Hunga Tonga-Hunga Ha‘apai, the uppermost part of a large underwater volcano. It rises 1.8 kilometers (1.1 miles) from the seafloor, stretches 20 kilometers (12 miles) across, and is topped by a submarine caldera 5 kilometers in diameter. The island is part of the rim of the Hunga Caldera and was the only part of the edifice that stood above water.
Now all of the new land is gone, along with large chunks of the two older islands.