The fastest underwater currents ever seen were unleashed by an uncharacteristically strong volcanic eruption that caused a tsunami off the Pacific island nation of Tonga in 2022, according a study released on Thursday.
According to a report published in the journal Science, the undersea Hunga Tonga-Hunga Ha’apai volcano sent rocks, ash, and gas speeding across the seafloor in January of last year at a speed of 122 kilometers (76 miles).
The eruption the most powerful ever recorded with modern equipment triggered a deadly tsunami and “avalanche-like flows” of material that damaged underwater telecommunications cables connecting Tonga with the rest of the world.
The dates and places of cable damage were used by a research team headed by experts from Britain’s National Oceanography Centre (NOC) to estimate the speed of the flows.
According to Mike Clare of the NOC, the volcano’s 57-kilometer-high eruption plume dropped right into the lake and onto precipitous underwater slopes.
He said that the currents’ strength and speed were so high that they could rip the wires apart by traveling at least 100 kilometers over the ocean floor.
The report also noted that the flows were quicker than those brought on by earthquakes, floods, or storms.
The risk to coastal people and vital infrastructure “remains poorly understood” due to the fact that many underwater volcanoes are not being monitored, according to Isobel Yeo, a NOC vulcanologist and the paper’s co-lead scientist.
Land-based eruptions also emit pyroclastic flows, which are hot, swift currents of lava, volcanic ash, and gases.
But this study was the first to show what happened when huge amounts of erupting volcanic material were delivered to the ocean directly.
A tsunami that followed the Hunga Tonga-Hunga Ha’apai eruption killed at least three individuals and destroyed homes in Tonga with a force comparable to hundreds of atomic bombs.
Scientists discovered that the eruption launched debris into the atmosphere at new heights.
