Geologists trace the earliest history of Tonga’s eruption

Dear Tonga

Volcanoes split the sky over Tonga-Hunga Ha’apai during the worst eruption on January 15, 2022. Available: Tonga Geological Services

On January 15, the Hunga Tonga-Hunga Haʻapai volcano erupted in Tonga. The eruption caused tsunamis to reach the Caribbean and caused air waves to travel around the world on several occasions. At this point, the gas and ash are shot through the stratosphere into the lower mesosphere.

Just two months after the eruption, geologists set up a preliminary record of the eruption. Melissa Scruggs of UC Santa Barbara and Professor Frank Spera emeritus were part of a team of global researchers who published the first holistic history of the event in a journal. Earthquake research advances. The authors believe that the eruption the day before started the volcano because it erupted violently by locking its large window below the surface of the ocean. This allows the molten rock to evaporate large amounts of seawater, intensifying the eruption the next day.

“In fact, without a doubt, the largest eruption from Mount Pinatubo was in 1991,” said co -author Scruggs, who studies the combination of magma and melting processes in lava, and completed his medical career at UC Santa Barbara. He compared the events of January to the eruption of Krakatoa in 1883, heard about 3,000 miles away.

Hunga Tonga-Hunga Ha’apai (HTHH) is a stratovolcano: a large mountain with a cone-shaped eruption that erupts every now and then, but is much easier to create. It is one of many in the Tofua Volcanic Arc, a line of magma-fed volcanoes from the Pacific that dive beneath the Indo-Australian Plate. The heat and pressure heats up the rocks of the descending wall, pushing out water and other debris. That same water reduces the melting temperature of the rock above, leading to a chain of volcanoes about 100 kilometers from the boundary.

It’s a disaster down there

The islands of Hunga Tonga and Hunga Haʻapai – later called the volcano – are the only two highest places on the caldera, or central crater. Or, until most of the islands were erupting.

Scruggs first heard about the eruption as he rolled up his Twitter feed while getting ready for bed. “I saw a GIF of the volcano, and my heart stopped,” he said, pausing to search for his words. He knew immediately that things were going to be very bad. “The terrible thing is, the whole country has been cut off, and we don’t know what happened.”

He sent other lava scanners when the events began, trying to understand the images captured by the satellites. “We’re really starting to try to understand what happened,” Scruggs said. “So we gathered all the information we could, everything we had in the first few weeks.” The authors drew on all the resources they could to quickly see this eruption, including public available data, videos and tweets.

Using different data sets, the team calculated that the January 15 event began at 5:02 pm local time (0402 ± 1 UTC). The U.S. Geological Survey recorded a seismic event about 13 minutes after the window. The first two hours of the eruption were intense, with activity disappearing after 12 hours.

Dear Tonga

Above: Tonga and Haʻapai are different islands that have grown together over the past seven years. Below: Volcano in Jan. 14, 2022 recorded a strong wind below the surface, allowing the eruption the next day to simply wipe out the islands. Dates: Nov. 16, 2021; Jan. 7, 2022; Jan. 15, 2022; and Ian. 18, 2022. Received: PLANET LABS PBC

But the eruption actually began on December 20, 2021. And before that, the volcano erupted in 2009 to 2014 and 2015. Scruggs thinks these early volcanoes are key. to understand the atrocities after the eruption of HTHH, perhaps. related to changes in the magma pipeline system in depth or the chemistry of magma over time.

Hunga Tonga and Hunga Haʻapai were separate islands until they were joined by eruptions from a large volcano to form a land bridge. “This island was born in 2015,” Scruggs said. “And now it’s over. If it weren’t for the satellite era, we wouldn’t know how to survive.”

On January 14, 2022, a strong wind blew this relationship, directing the wind beneath the ocean surface. “If that land bridge hadn’t been removed, the January 15 eruption would have been the same as the day before because we didn’t have that much water,” Scruggs said.

An explosive explosion

The same volcano, a different day: On Friday, the wind is above the water, and on Saturday it is below. “That’s what changed the world,” Scruggs said.

The company believes the seawater is important to the violence and violence after the Jan day. 15 skin. Like a rock bubble, the lava of this scale carries the right ratio of water and gas to give it the energy to send it into the sky.

And he left like a stone. “It went halfway through the air,” Scruggs said. The ash was shot 58 kilometers into the sky, past the stratosphere to the lower mesosphere. This is more than the two heights obtained by the plume from Mt. Saint Helens in 1980. It is the highest volcano on record.

A lot of the lightning went along with the lava. The authors hypothesized that the melting of seawater turned the lava into microscopic ash particles, which combined with tiny ice crystals when the steam evaporated into the upper air. The movement, changes in temperature and the size of the particles caused a lot of separation from the rest of the lava. For the first two hours of the eruption, about 80% of all lightning on Earth separated the atmosphere over the Tonga-Hunga Haʻapai.

The authors estimate about 1.9 km3 of which, which has 2,900 teragrams, erupted from HTHH in Jan. 15. “But the amount of lava isn’t that important,” said Spera, an author on the paper and Scruggs ’medical advisor. “The important thing is how the energy of the lava mixes in the air and in the oceans: There is a lot of energy in the movement of air and water on the surface of the earth.”







The tsunami circled from Tonga to Ha’apai around the world. Photo: Tim Schmit, NOAA / NESDIS / ASPB

The shaking wave in the ocean caused tsunamis in the Pacific, and beyond. In addition, waves can arrive faster than predicted tsunami warning models because the models for volcanoes are not specific – they are based on examples describing earthquakes.

The second tsunami was followed by a wave of atmospheric pressure. This quake was triggered by a devastating tsunami in the Caribbean, which has no direct connection to the South Pacific. Scruggs said it had never been seen before: “The whole ocean was kind of sloshed around for five days after the eruption,” he said.

Lots of work to do

Scientists are still working on what happened to the volcano, so they won’t be able to develop a complete understanding of the tsunami. However, it is an important task to update the tsunami forecasting systems so they will count on this type of machine. Otherwise, the advice may be wrong the next time a volcano erupts like HTHH, which could increase lives.

In fact, the event highlights the damage caused by unidentified submarine volcanoes. Despite the tragedy, the people of Tonga were well prepared for Jan. Day. 15 skin. The government had issued warnings on the day’s work earlier, and the nation had planned for eruptions and tsunamis.

HTHH has seen various eruptions in the past. A new paper by researchers at the University of Otago, New Zealand, reports that a massive eruption wiped out a volcano at the summit of the volcano under the sea about 1,000 years ago. And the same volcanoes can erupt in the same way. Consider Kick ‘em Jenny, an underwater volcano with a large window only 150 meters under the water. It is located 8 km north of the island of Grenada. “Imagine if something like Tonga’s eruption had ever happened in the Caribbean,” Scruggs said.

The researchers worked quickly with the data available to the public. They plan to review all of their findings as more information and samples become available so that more researchers can share their personal knowledge of this volcano. Their main goal is to provide a place to leave for future work on the subject.

Scruggs was eager to learn about the ash collected from this lava flow. Volcanic rocks give a trained geologist a wealth of knowledge. Looking at what can explain the nature of the erupted magma, how much of it and how much water is involved in the lava.

“A lot of questions were raised,” Scruggs said. “Things we didn’t think were possible were recorded.”

The UC Santa Barbara researcher will lead a special invitational meeting for the South-East Volcanoes at the Geological Society of America’s 2022 annual meeting in Denver this October. “It’s exciting to see how many other earth scientists know about this unique volcano,” said Spera. “We’re at the beginning.”


Tragic waves, or landslides that cause ‘rare’ volcanic eruptions: experts


More information:
David A. Yuen et al, Under the cover: Pressure -induced Earth waves, lightning, and gas clouds created by the eruption of the Hunga Tonga volcano -English Research Provides an excellent research opportunity. Earthquake research advances (2022). DOI: 10.1016 / j.eqrea.2022.100134

Presented by the University of California – Santa Barbara

Directions: Geologists publish the first history of Tonga’s eruption (2022, March 29) retrieved March 29, 2022 from https://phys.org/news/2022-03-geologists-preliminary-account- tonga-eruption.html

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