A New Zealand-led team of marine geologists investigating an underwater volcano that erupted Jan. 15 in the Tongan archipelago in the South Pacific has found it to be the “largest ever recorded” with modern equipment.
The Hunga Tonga-Hunga Ha’apai volcano, which generated a tsunami and sonic boom that circled the globe twice, was captured in dramatic satellite images that showed a huge cloud of ash and steam in the atmosphere.
A team of oceanographers, scientists and marine geologists led by the New Zealand National Institute for Water and Atmospheric Research (NIWA), with the help of a robotic boat operated remotely in the UK by Sea-Kit International, has completed the “most complete survey until now”. in the underwater Tongan volcano. They found that nearly 10 cubic kilometers of seafloor had been moved – the equivalent of 2.6 million Olympic swimming pools.
“The eruption reached record highs and was the first we’ve ever seen to break through into the mesosphere,” said Kevin Mackay, NWA marine geologist. “It was like shooting a gun straight into the air.”
“While this eruption was large, one of the largest since Krakatoa in 1883, there have since been others of similar size that have not behaved in the same way. The difference here is that it’s an underwater volcano and that’s part of the reason why we have such big tsunami waves,” Mackay added.
The team of scientists also unraveled new information about the volcano’s underwater pyroclastic flows — a mixture of hot, dense volcanic ash, lava fragments and gas ejected from the volcano — by examining sediment remnants found 50 miles away.
“The sheer force of the flows is amazing – we saw deposits in valleys beyond the volcano, where the international cable is, meaning they had enough force to flow uphill over huge ridges and then back down,” said Dr Emily Lane, NIWA Chief Scientist.
The volcano was also found to have injected a huge plume of water vapor into Earth’s stratosphere. According to NASA, only the 2015 eruption of Calbuco in Chile and the 2008 eruption of Kasatochi Island in Alaska released significant amounts of high-altitude water vapor.
“We’ve never seen anything like it,” Luis Millán, an atmospheric scientist at NASA’s Jet Propulsion Laboratory, said in a statement in August.
The crater of the Hunga Tonga-Hunga Ha’apai volcano was also found to be 700 meters deeper than before the eruption.