Tonga's volcanic eruption is the strongest in over a century - CNN

Scientists have already begun to compile what happened on January 15 when the Hunga Tonga-Hunga Ha’apai volcano erupted under the sea. approximately 65 kilometers (40 miles) north of the Tongan capital that killed at least three people. The eruption contradicted easy explanation and changed scientists ’understanding of this type of volcano.
The volcanic eruption sent rarely observed pressure waves around the world for six days and unleashed an unexpected type of tsunami wave, according to two new studies published Thursday in the journal Science. The huge plume of gases, water vapor and dust also created storm force in space, NASA said in a separate study published this week.

Early data after this eruption suggested it was the largest since the 1991 Mount Pinatubo eruption in the Philippines, but Science studies, involving 76 scientists in 17 countries, suggested that the pressure waves released its similar to that formed by the cataclysmic 1883 Krakatoa eruption and 10 times larger than in 1980 Eruption of Mount St. Helens in Skamania County, Washington.

The Tonga eruption was “unusually vigorous,” the researchers in the Science study wrote. Low-frequency atmospheric pressure waves, called Lamb waves, were seen after the explosion rotated the planet in one direction four times and in the opposite direction three times, they revealed.

A relatively rare phenomenon, these waves travel at the speed of sound. People do not see them and are slower than shock waves, because they are sometimes incorrectly described, says study author Quentin Brissaud, a geophysicist of the Norwegian Seismic Array in Oslo. Sheep waves were also observed during the Cold War after atmospheric nuclear tests.

“It’s pretty rare. So lamb waves are actually associated with large air volume displacements. And they usually propagate over the Earth’s surface,” said coauthor Jelle Assink, senior geophysicist in the seismology and acoustics department at Royal Netherlands Meteorological Institute.

Moving over many oceans and seas, the Lamb’s pressure waves from the eruption created the rapid movement of scattered tsunamis.

Traditional tsunamis are usually associated with sudden changes in the ocean floor such as during an earthquake. More importantly, these so -called meteotsunamis travel faster than traditional tsunamis, arriving two hours earlier than expected, and lasting longer, which could have implications for early systems. warning.

And because an atmospheric pressure wave created them, tidal waves appear to “jump across continents,” with tsunamis recorded from the Pacific to the Atlantic, says co-author Silvio De Angelis, professor ng volcanic geophysics in the department of Earth, ocean and ecological science at the University of Liverpool in the United Kingdom.

The research also revealed that the audible sound from the explosion was detected more than 10,000 kilometers (6,000 miles) from the source in Alaska. – where it was heard as a series of booms. The eruption of Krakatoa in 1883 was heard 4,800 kilometers (2,980 miles) away, the study said, although it was less systematically reported than in Tonga.

A lithograph depicts clouds pouring from the Krakatoa volcano during the cataclysmic 1883 eruption in southwestern Indonesia.

The researchers said more data is needed to understand the mechanism of the explosion.

It is thought that one of the reasons for such a vigorous eruption – which creates an umbrella cloud 30 kilometers (about 19 miles) high and a plume 58 kilometers (36 miles) high – is because “heat enters and gas-charged magma in contact with the (seawater) very rapidly, “De Angelis said via email. “The rapid transfer of intense heat between hot magma and cold water causing violent eruptions capable of tearing up magma. “

Disruption of space

Another study, published Tuesday in Geophysical Research Letters, found that the Tonga volcano also created chaos in space, prompting the strength of the wind storm, based on data from NASA’s Ionospheric Connection Explorer, or ICON, mission and the European Space Agency’s Swarm satellite.
The giant plume of gases, water vapor and dust pushed into the sky by the explosion created large disturbances in atmospheric pressure, leading to strong winds, NASA said in a statement. As these winds expand up into the thinner layers of the atmosphere, they begin to move faster.

“Reaching the ionosphere and the edge of the galaxy, ICON clocked wind speeds up to 450 mph-making them the strongest winds below the 120-mile altitude the mission has measured since its launch,” the NASA.

(From left) Satellite images from January 6 and January 18 show the impact of a volcanic eruption near Tonga.

In the ionosphere, where the Earth’s atmosphere meets the galaxy, strong winds also strike electric currents, which circulate particles from their common electric current to the east-called the equatorial electrojet-toward the westward in a short time, and the electrojet jumped. up to five times its normal peak power.

“It’s very surprising to see the electrojet so completely reversed by something that happened on the Earth’s surface,” said Joanne Wu, a physicist at the University of California, Berkeley, and a coauthor of the new Geophysical Research Letters study.

“It’s something we’ve only seen before in strong geomagnetic storms, which are a form of weather in space caused by particles and radiation from the sun.”

Said Brian Harding, a physicist at UC Berkeley and lead author the Tonga eruption “allows us to test the lesser-understood connection between the lower atmosphere and space.”

He added, “The volcano created one of the biggest galaxy chaos we’ve seen in modern times.”

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