Tonga eruption was highest recorded volcanic plume

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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 broke through the third layer of Earth’s atmosphere.

It was the highest recorded volcanic plume and reached the mesosphere, where meteors and meteorites usually break up and burn up in our atmosphere.

The mesosphere, about 50 to 80 kilometers above the Earth’s surface, is located above the troposphere and stratosphere and under two other layers. (The stratosphere and mesosphere are dry atmospheric layers.)

The volcanic plume reached a height of 57 kilometers at the most. It surpassed previous record holders such as the 1991 eruption of Mount Pinatubo in the Philippines at 24.8 miles (40 kilometers) and the 1982 El Chichón eruption in Mexico, which reached 19.2 miles (31 kilometers).

Researchers used images captured by satellites passing over the eruption site to confirm the plume’s height. The eruption occurred on January 15 in the South Pacific Ocean off the Tongan archipelago, an area covered by three geostationary weather satellites.

A study detailing the findings published Thursday in the journal Science.

The towering plume sent to the upper atmosphere contained enough water to fill 58,000 Olympic-size swimming poolsaccording to previous detections from a NASA satellite.

By understanding the plume’s height, researchers can study the eruption’s impact on the global climate.

Determining the plume’s height posed a challenge for researchers. Typically, scientists can measure the height of a plume by studying its temperature — the colder a plume, the higher it is, said lead study co-author Dr. Simon Proud of RAL Space and a research associate at the National Center for Earth Observation and Oxford University.

But this method could not be applied to the Tonga event due to the violent nature of the eruption.

“The eruption pushed through the atmospheric layer we live in, the troposphere, to the upper layers where the atmosphere warms up again the higher you go,” Proud said via email.

“We had to come up with a different approach, using the different views from weather satellites that are on either side of the Pacific and some pattern recognition techniques to calculate altitude. That has only become possible in recent years, because 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 plume appearance from multiple angles as captured by the weather satellites. The satellites captured images every 10 minutes, documenting the dramatic changes in the plume as it rose from the ocean. The images reflected differences in the plume’s position from different lines of sight.

The eruption “went from nothing to a 57-kilometer tower of ash and clouds in 30 minutes,” Proud said. Members of the team also noticed rapid changes in the crest of the eruptive plume that surprised them.

“After the first major eruption to 57 kilometers, the central dome of the plume collapsed inward, before another plume appeared shortly after,” Proud said. “I didn’t expect something like this to happen.”

The amount of water the volcano has released into the atmosphere is expected to temporarily warm the planet.

“This technique allows us not only to determine the maximum height of the plume, but also the different levels in the atmosphere where volcanic material has been released,” said study co-author Dr. Andrew Prata, a postdoctoral research assistant in the Clarendon Laboratory subdivision. atmospheric, oceanic and planetary physics at the University of Oxford, via email.

If you know the plume’s composition and height, you can see how much ice has been sent into the stratosphere and where ash particles have been released.

Altitude is also critical to aviation safety, as 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 ever recorded. When the submarine volcano erupted 65 kilometers north of the capital of Tonga, it triggered a tsunami and shock waves that rippled around the world.

Research is underway to determine why the eruption was so powerful, but it may have occurred underwater.

The heat from the eruption evaporated the water and “created a steam explosion that was much more powerful than a volcanic eruption would normally,” Proud said.

“Examples such as the Hunga Tonga-Hunga Ha’apai eruption show that magma-seawater interactions play an important role in producing highly explosive eruptions that can inject volcanic material to extreme heights,” Prata added.

Next, the researchers want to understand why the plume was so high, as well as its composition and its ongoing impact on the global climate.

“When people think of volcanic plumes, they often 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 a fairly modest amount of sulfur dioxide and sulfate aerosols formed soon after the eruption.”

In this research, Proud wants to use the multi-satellite altitude technique to create automatic warnings for severe storms and volcanic eruptions.