The largest volcanic eruption ever recorded on Earth

An eruption of a volcano in Tonga in January 2022 has been confirmed as the largest eruption ever recorded in the atmosphere by modern equipment.

It was much larger than any volcanic event of the 20th century, or even any atomic bomb test conducted after World War II.

The assessment was presented in two academic articles, published in the journal Science, that reviewed all the data.

In recent history, it is likely that only the eruption of Krakatoa in 1883 could rival the resulting atmospheric turbulence. It is believed that this disastrous event in Indonesia killed more than 30 thousand people.

Fortunately, the eruption of the Hongga Tonga-Hung Hapai (HTHH) volcano under the sea on January 15 this year, located in the South Pacific, led to very few deaths, although it also caused large tsunamis.

“Tonga was a really global event, just like Krakatoa, but now we have all the geophysical monitoring systems in place, and they’ve recorded something really unprecedented in recent data.” , in the United States, and is the lead author of one of the articles.

Scientists now have access to an extraordinary array of terrestrial and space-based instruments, including barometric pressure sensors, seismographs, hydrophones, and a fleet of satellites that monitor Earth across the entire light spectrum.

The massive eruption in Tonga, which came after several weeks of seamount activity, produced various types of atmospheric pressure waves that spread over vast distances.

In the audible frequency range, people 10,000 km away in Alaska reported hearing a recurring bang.

The infrasound signal was picked up by the global network of detectors created to monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty.

Infrasound frequencies are slightly lower than what humans can hear.

Network data indicated that the eruption of the Tonga volcano produced an atmospheric pressure wave comparable to the largest nuclear explosion of all time? The Tsar Bomb, detonated by the Soviets in 1961? , but it lasted four times.

The articles discuss in depth the disturbances caused by the so-called Lamb waves, named after the mathematician Horace Lamb in the early 20th century.

They are energetic waves in the air that propagate at the speed of sound, along a directed path across the surface of the planet. It is also non-dispersive, which means that it keeps its shape as it moves and is therefore visible for a long time.

Convective wave pulsations from the Tonga eruption have been seen orbiting the Earth at least four times.

In the United Kingdom, which is located about 16,500 km from Tonga, these pulsations began to arrive on the night of the 15th, about 14 hours after the eruption of the volcano on the other side of the planet.

They have lifted the clouds over the UK.

Giles Harrison, an atmospheric physicist at the University of Reading in the UK, and co-author of one of the articles recalls.

“If you want proof that the atmosphere is remarkably interconnected, it’s here. And what happens on one side of the planet can spread to the other side at the speed of sound.”

Where the convective waves joined the ocean waves, were they able to generate tsunamis? Not only in the Pacific Ocean, but also in the Atlantic and Mediterranean.

Scientists are still investigating the generation of the nearby tsunami that struck the coasts of the Tonga archipelago.

Some of them were undoubtedly created by pressure waves from the volcano that pushed up the surface of the water, but investigations are underway to determine if the collapse of part of the volcano may also have contributed significantly.

This will be evident in the seafloor mapping projects, the results of which are expected to be released in the coming weeks.

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