Tonga Volcano Eruption Caused by Underground Gas Buildup Instead of Magma, Seawater Reaction [Study]

The Tonga volcano eruption in 2022 was a powerful blast from an underwater mountain. The natural disaster sent volcanic ash and water vapor into the atmosphere and generated tsunami waves which swept through the Tongan islands in the Pacific Ocean. The catastrophic event killed multiple people, destroyed of hundreds of structures, and displaced over a thousand others in the region.

Following the major Tonga eruption in January 2022, multiple studies have described the causes, nature, and implications of the event to communities and the environment. The volcanic explosion has been described by scientists as a rare "Plinian eruption." From triggering atmospheric shockwaves to global mega-tsunamis, the eruption was perceived by many to be caused by the reaction between magma and seawater.

However, a new study in April 2024 suggests an alternative explanation behind the eruption of the Hunga Tonga-Hunga Ha'apai volcano. Instead of being caused by molten rock material and seawater interaction, the event was triggered by an underground gas buildup. It involves the reactions of gas and solid particles to choke magmatic gas discharge, increasing internal gas pressure, researchers say.

2022 Tonga Volcano Eruption

The Tonga volcano eruption on January 15, 2022, created the "largest underwater explosion" in modern history, based on records by modern scientific instruments. The eruption involved a gigantic amount of water and volcanic gases, which are higher than any other eruption during the satellite era, according to the National Oceanic and Atmospheric Administration (NOAA).

Prior to the major eruption on January 15, the underwater volcano Hunga Tonga-Hunga Ha'apai experienced smaller eruptions between December 19, 2021, and January 13, 2022. The government of Tonga confirmed the deaths of at least four people from the disaster. Meanwhile, more than a dozen was injured and others have been reported missing following the eruption and tsunamis.

Underground Gas Buildup

Just like other underwater volcanic eruptions, some scientists from previous research thought that the cause of the 2022 Tonga eruption was magma and seawater reaction, as mentioned earlier. However, a new study published in the Journal of Volcanology and Geothermal Research on April 21 theorizes that an underground gas buildup was the culprit behind the eruption.

The international research team involved in the study, including Australia and the United States, explains that a hydraulic failure at the underwater volcano triggered a powerful gas explosion, atmospheric air blast and tsunami. The findings are based on new evidence-based model of the Hunga Tonga eruption, which was potentially triggered by a built-up gas below a seal inside the volcano.

In a report by the U.S. Geological Survey (USGS) in August 2022, the Tonga eruption surprised scientists since the volcanic explosion triggered two types of tsunamis: classic tsunamis and meteotsunamis. The former is caused by the displacement of large water volumes, while the latter occurs due to fast-flowing pressure disturbing the atmosphere, the USGS adds.