REPUBLIKA.CO.ID, JAKARTA — Scientists have finally mapped the giant magma pipe system that gave birth to volcanic explosions Southerners in the southwest Pacific Ocean. This is known almost two years after the powerful eruption that broke the record.
On January 15, 2022, the volcano beneath the island of Hunga Tonga-Hunga Ha’apai exploded with such force that it triggered the most intense thunderstorm ever recorded and the first documented mega tsunami since ancient times.
The eruption was felt around the world, but the volcano’s underwater conditions posed a challenge for scientists trying to understand how the powerful explosion occurred.
Now, in a study published December 15 in the journal Science Advances, researchers have mapped slight variations in the gravitational pull in the waters around the island before and after the eruption and found that the explosion was likely caused by two magma chambers merging.
“I was very surprised that we could actually describe a relatively large magmatic system using this kind of data set and method,” said lead author Hélène Le Mével, a volcanologist and staff scientist at the Carnegie Institution for Science in Washington DC, as reported by Space, Sunday (12/31/2023).
This kind of work is “rarely done to study underwater volcanoes,” Le Mével told Livescience in an email.
The magma reservoirs are at different depths of between two and 10 kilometers beneath the volcano and are likely to store large amounts of liquid magma before the 2022 eruption, according to the study.
The researchers found that the explosion ejected about 30 percent of the magma, more than nine cubic kilometers, from the shallow central chamber. This is what causes the top of the volcano to collapse and form an 850 meter deep bowl-like depression called a caldera.
When the pressure in the central reservoir drops, it opens a channel between the two chambers. It is also possible that magma from a gas-rich source deep in the Earth’s crust rose into the central chamber, which “may also explain the enormity of the 2022 eruption,” according to the study.
The third magma pocket, located northwest of the central chamber, appears to be disconnected from the system and may represent “an older, hardened zone of soft and wet mass,” the authors wrote.
According to the study, up to 26 cubic kilometers of eruptive magma is still hiding in two main reservoirs beneath Hunga volcano. This is enough to fill 10 million Olympic-sized swimming pools. (Eruptible magma is defined as magma that has more than 50 percent melt and a low crystalline solid content.
Although the study revealed what triggered the volcano, it could not pinpoint what triggered the massive eruption.
“The gravity results alone do not directly allow us to deduce the trigger for the eruption,” Le Mével said, but they do give researchers “an idea of where and how much magma may be stored beneath the volcano.”
These findings may also be limited because they used satellite data that may be affected by ocean waves and changes in gravity from the sea floor to the sea surface, the researchers said in the study.
“We only have information about what changed over the course of a year so we can’t say specifically what happened during the eruption,” Le Mével said. But the data shows “new pathways between reservoirs have been created,” he added.
2023-12-31 15:42:12
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