Tonga Volcano Eruption Caused ‘Rare’ Atmospheric Waves, ‘High-Frequency Infrasound’, Study Reveals

The 15 January 2022 submarine eruption of the Hunga volcano devastated the island nation of Tonga, sending ash 100,000 feet (about 30 kilometres) high into the sky, with the effects felt as far away as the US West Coast.

The massive January 2022 Hunga volcano eruption created an atmospheric pulse that caused an unusual tsunami-like disturbance arriving at Pacific shores sooner than the actual tsunami, a new study has revealed.

The research focused on exploring a variety of atmospheric wave types, including booms heard 6,200 miles (10,000 km) away in Alaska, as a result of the submarine eruption that devastated the island nation of Tonga on 15 January.

The study’s lead author David Fee of the University of Alaska Fairbanks Geophysical Institute said that the Hunga eruption had prompted unprecedented insight into the behavior of some atmospheric waves.

He voiced hope that scientists “will be better able to monitor volcanic eruptions and tsunamis by understanding the atmospheric waves from this eruption”.

“The atmospheric waves were recorded globally across a wide frequency band, and by studying this remarkable dataset we will better understand acoustic and atmospheric wave generation, propagation and recording. This has implications for monitoring nuclear explosions, volcanoes, earthquakes and a variety of other phenomena”, Fee underlined.

In this context, the researcher specifically mentioned the behaviour of the eruption’s Lamb waves, which typically can last from minutes to several hours.

During the Hunga eruption, these waves travelled along Earth’s surface and circled the planet in one direction four times and in the opposite - three times, something that was also observed in the 1883 Krakatoa eruption, one of the deadliest and most destructive volcano events in history.

“Lamb waves are rare. We have very few high-quality observations of them. By understanding the Lamb wave, we can better understand the source and eruption. It is linked to the tsunami and volcanic plume generation and is also likely related to the higher-frequency infrasound and acoustic waves from the eruption,” Fee pointed out.

The infrasound, which is too low in frequency to be heard by humans, arrived after the Lamb waves, which were followed by audible sounds. They travelled about 6,200 miles (9,000 km) to Alaska, where they were heard around the state as repeated booms about nine hours after the eruption, according to the researcher.

“I heard the sounds but at the time definitely did not think it was from a volcanic eruption in the South Pacific,” he said, pledging that scientists “will be studying these signals for years to learn how the atmospheric waves were generated and how they propagated so well across Earth”.