Tonga eruption
Volcanic lightning split the sky above Hunga Tonga-Hunga Ha'apai during a particularly violent eruption January 15, 2022. Credit: Tonga Geological Services

On January 15th, the nation of Tonga was devastated by a volcano. The eruption generated atmospheric waves that traveled around the globe several times. Gas and ash were shot into the lower mesosphere by the volcano.

A preliminary account of how the eruption unfolded has been put together by geologists. The first comprehensive account of the event was published in the journal Earthquake Research Advances. The authors think that an eruption the day before may have caused the volcano to explode by sinking its main vent below the ocean's surface. The volcanic eruption was intensified the next day because of this.

This is the largest eruption since Mt. The author of Pinatubo in 1991, who studies magma mixing and triggering eruption mechanisms, recently completed her doctorate at UC Santa Barbara. The 1883 eruption of Krakatoa was heard 3,000 miles away.

A large, cone-shaped mountain that is prone to periodic violent eruptions, but which usually experiences milder activity is called the Hunga Tonga-Hunga Ha. The Tofua Volcanic Arc is a line of volcanoes fed by magma from the Pacific Plate. Pressure and heat cook the rocks of the descending plate. A chain of volcanoes about 100 kilometers from the plate boundary are caused by the decrease in the melting temperature of the rock above.

There is a submerged danger.

The two highest points along the rim of the caldera are the islands of Hunga Tonga and Hunga Ha. The eruption blew most of the islands sky high.

As she was getting ready for bed, she scrolled through her feed and saw a picture of the satellite eruption. She knew that the event would cause a lot of destruction.

As the events unfolded, she was trying to understand the images that satellites had captured.

The January 15 event began at 5:02 p.m. local time, using a variety of data sets. 13 minutes later, the U.S. Geological Survey recorded a earthquake at the vent location. The first two hours of the eruption were violent, with activity fading after 12 hours.

Tonga eruption
Top: Hunga Tonga and Hunga Ha’apai were separate islands that grew together over the course of seven years. Bottom: The eruption on Jan. 14, 2022 sunk the main vent below sea level, enabling the eruption the following day to all but obliterate the islands. Dates: Nov. 16, 2021; Jan. 7, 2022; Jan. 15, 2022; and Jan. 18, 2022. Credit: PLANET LABS PBC

The eruption activity began on December 20, 2021. The volcano had erupted in the past. The violence behind the recent eruption may be related to changes in the plumbing system at depth or the chemistry of the magma over time.

The two islands were united by eruptions from the volcano's main vent, which created a land bridge. We would not have known it existed if it wasn't for the satellite era.

The January 15 eruption might have behaved the same as the day before if the land bridge had not been taken out.

An explosion.

On Friday the vent was above the water, and on Saturday it was below.

The team believes that the force behind the Jan. 15 eruption was caused by the seawater. An eruption of this scale takes the right ratio of water and gas to send it up in the air.

It took off like a rocket. The upper atmosphere was shot 58 kilometers into the lower mesosphere. This is more than twice the height reached by the Mt. plume. Saint Helens was in 1980. It was the tallest volcanic eruption.

The eruption was accompanied by a lot of lightning. The authors think that the lava split into tiny ash particles and ice crystals when the steam froze in the upper atmosphere. The motion, temperature change and size of the particles created static charge separation above the eruption. About 80% of all lightning strikes on Earth split the sky above the volcano.

Spera said the volume of the eruption was not a big deal.

The shockwave from Hunga Tonga-Hunga Ha’apai traveled around the world. Credit: Tim Schmit, NOAA/NESDIS/ASPB

The waves caused by the ocean's shock traveled throughout the Pacific and beyond. The warning models are based on equations that describe earthquakes, so the wave arrived faster than predicted.

The atmospheric pressure wave caused a second wave. There is a meteo-tsunami in the Caribbean that has no connection to the South Pacific. The whole ocean was covered in mud for five days after the eruption.

There is a lot of work to be done.

Scientists are still figuring out what happened at the volcano, so they don't have a complete understanding of the wave. It is an important task to update the forecast systems so they account for this type of mechanism. If warnings are incorrect the next time a volcano erupts, more lives could be lost.

The event shows the danger posed by unmonitored submarine volcanoes. The people of Tonga were prepared for the eruption. The nation had plans in place for earthquakes and eruptions, and the government had issued warnings based on activity the previous day.

In the past, HTHH has experienced violent eruptions. The caldera at the summit of the undersea volcano was destroyed by a large eruption about 1,000 years ago, according to a recent paper by researchers at the University of Otago, New Zealand. Similar volcanoes could erupt in the same way. The main vent of Kick Jenny is 150 meters underwater. It is 8 km north of the island of Grenada.

Only publicly available data was used by the researchers. As more information and samples become available and more researchers publish their own findings, they plan to revisit all of their findings. They wanted to provide a point of departure for future work on the topic.

The ash collected from this eruption is something that is important to Scruggs. Volcanic rock has a lot of information. Examining the material could show how much of the eruption was caused by the type of magma and how much was seawater.

There are so many questions that have been raised.

The UC Santa Barbara researchers will lead a special invited session on the eruption at the Geological Society of America's annual meeting in Denver in October.

More information: David A. Yuen et al, Under the Surface: Pressure-Induced Planetary-Scale Waves, Volcanic Lightning, and Gaseous Clouds Caused by the Submarine Eruption of Hunga Tonga-Hunga Ha'apai Volcano Provide an Excellent Research Opportunity, Earthquake Research Advances (2022). DOI: 10.1016/j.eqrea.2022.100134 Citation: Geologists build preliminary account of Tonga eruption (2022, March 29) retrieved 29 March 2022 from This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.