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When the Hunga Tonga-Hunga Ha’apai volcano erupted underwater in January, it created a plume of ash and water that ruptured the third layer of Earth’s atmosphere.
It was the highest recorded volcanic plume and reached the mesosphere, where meteorites and meteorites usually break up and burn up in our atmosphere.
The mesosphere, about 31 to 50 miles (50 to 80 kilometers) above the Earth’s surface, lies above the troposphere and stratosphere and below two other layers. (The stratosphere and mesosphere are dry atmospheric layers.)
The volcanic plume reached an altitude of 35.4 miles (57 kilometers) at its highest point. It surpassed previous record holders such as the 1991 Mount Pinatubo eruption in the Philippines at 24.8 miles (40 km) and the 1982 El Chichón eruption in Mexico, which reached 19.2 miles (31 km).
The researchers used images captured by satellites passing over the site of the explosion to confirm the height of the plume. The eruption occurred on January 15 in the South Pacific Ocean off the Tonga archipelago, an area covered by three geostationary weather satellites.
A study detailing the findings was published Thursday in the journal Science.
The towering plume sent into the upper atmosphere contained enough water to fill 58,000 Olympic-sized swimming pools, according to previous NASA satellite detections.
Understanding the height of the plume can help researchers study the impact the eruption may have on global climate.
Determining the height of the plume has been a challenge for researchers. Typically, scientists can measure the height of a plume by studying its temperature — the colder a plume is, the higher it is, said lead study co-author Dr. Simon Proud of RAL Space and a researcher at the National Earth Observation Center and the University of Oxford.
But this method could not be applied to the Tongan event because of the violent nature of its outbreak.
“The explosion pushed through the layer of atmosphere we live in, the troposphere, into the upper layers where the atmosphere heats up again as you go higher,” Proud said via email.
“We had to come up with another approach, using the different views given by weather satellites on opposite sides of the Pacific and some pattern matching techniques to calculate the altitude. This has only become possible in recent years, as even ten years ago we didn’t have the satellite technology in space to do this.”
The research team relied on the “parallax effect” to determine the height of the plume, comparing the difference in the appearance of the plume from multiple angles as captured by weather satellites. The satellites took images every 10 minutes, recording the dramatic changes in the plume as it exited the ocean. The images reflected differences in plume position from different angles.
The eruption “went from zero to a tower of ash and cloud 57 kilometers high in 30 minutes,” Proud said. Team members also noticed rapid changes at the top of the explosive plume that surprised them.
“After the initial big burst at 57km, the central dome of the plume collapsed inwards, before another plume appeared shortly afterwards,” Proud said. “I didn’t expect something like this to happen.”
The amount of water released by the volcano into the atmosphere is expected to warm the planet temporarily.
“This technique not only allows us to determine the maximum height of the plume but also the various levels in the atmosphere where volcanic material was released,” said study co-author Dr. Andrew Prata, a postdoctoral research assistant in the Clarendon Laboratory sub-division. atmospheric, oceanic and planetary physics at the University of Oxford, via email.
Knowing the composition and height of the cloud can reveal how much ice was sent into the stratosphere and where ash particles were released.
Altitude is also critical to aviation safety because volcanic ash can cause jet engine failure, so avoiding ash plumes is key.
The height of the plume is yet another emerging detail of what has become known as one of the most powerful volcanic eruptions on record. When the undersea volcano erupted 40 miles (65 kilometers) north of the Tongan capital, it triggered a tsunami as well as shock waves that rippled around the world.
Research is continuing to unlock why the explosion was so powerful, but it may be because it happened underwater.
The heat of the eruption vaporized the water and “created a steam explosion much more powerful than a volcanic eruption would normally be,” Proud said.
“Examples such as the Hunga Tonga-Hunga Ha’apai eruption demonstrate that magma-seawater interactions play an important role in producing highly explosive eruptions that can inject volcanic material at extreme altitudes,” Prata added.
Next, researchers want to understand why the plume was so high as well as its composition and ongoing effects on global climate.
“Often when people think of volcanic plumes they think of volcanic ash,” Prata said. “However, preliminary work on this case reveals that there was a significant amount of ice in the plume. We also know that there was a fairly modest amount of sulfur dioxide and sulfate aerosols that formed quickly after the explosion.”
Proud wants to use the multi-satellite altimetry technique in this study to create automatic warnings of severe storms and volcanic eruptions.
