[Rockhounds] Record-shattering Tonga volcanic eruption wasn't triggered by what we thought

[Kreigh Tomaszewski]

Scientists have proposed an alternative explanation for why the
*record-shattering
Tonga volcanic eruption*
<https://www.livescience.com/tonga-volcanic-eruption-fast-waves> of 2022
was so violent: The explosion may have been triggered by gas, rather than
by a reaction between magma and water as previously suggested.

Hunga Tonga-Hunga Ha'apai, an underwater volcano in the South Pacific
Ocean, erupted on Jan. 15, 2022, unleashing the *most intense lightning
storm ever recorded*
<https://www.livescience.com/planet-earth/tonga-2022-eruption-triggered-the-most-intense-lightning-storm-ever-recorded>
and
the *first known mega-tsunami since antiquity*
<https://www.livescience.com/planet-earth/tsunami/1st-mega-tsunami-on-record-since-antiquity-was-triggered-by-tonga-volcanic-eruption>.
Previous research indicated that the underwater eruption was *fueled by two
merging magma chambers*
<https://www.livescience.com/planet-earth/volcanos/tonga-volcano-eruption-was-fueled-by-2-merging-chambers-that-are-still-brimming-with-magma>,
but exactly what sparked the blast has remained unclear.

"Previous models have assumed magma-seawater interaction, but heat transfer
considerations show this to be untenable and direct evidence is not
provided by satellite data," researchers wrote in a new study, published
online April 21 in the *Journal of Volcanology and Geothermal Research*
<https://doi.org/10.1016/j.jvolgeores.2024.108077>. Instead, they wrote,
bathymetric (water depth) and satellite observations point to a colossal
buildup of gas beneath a seal inside the volcano that suddenly broke on
Jan. 15 after a series of smaller eruptions between Dec. 19, 2021, and Jan.
13, 2022.

This seal may have formed through a reaction between volcanic rocks and gas
rising from the depths of the volcano. "It is now well established that
fast reactions occur between the [sulfur dioxide] and [hydrogen chloride]
contents of magmatic gases to produce minerals including anhydrite, quartz
and sulfides as they expand from source to surface," the researchers wrote
in the study. "Their formation leads to a choking of flow paths and
potentially sealing of the gas flux through the volcano."

https://www.livescience.com/planet-earth/volcanos/record-shattering-tonga-volcanic-eruption-wasnt-triggered-by-what-we-thought-new-study-suggests