Tonga’s underwater volcano eruption broke two records

An undersea volcano in the South Pacific erupted last month and shattered two records simultaneously: The volcanic plume reached higher heights than any eruption ever captured in the satellite record, and the eruption generated an unprecedented number of lightning strikes – nearly 590,000 over three days, Reuters reported.

“The combination of volcanism Heat and the amount of superheated moisture from the ocean made this eruption unprecedented. It was like hyper-fuel for a mega-storm,” said Kristopher Bedka, an atmospheric scientist at NASA’s Langley Research Center who specializes in the study of extreme storms. NASA Earth Observatory statement. “The plume went 2.5 times higher than any thunderstorm we’ve ever seen, and the eruption generated an incredible amount of lightning.”

the volcanocalled Hunga Tonga-Hunga Ha’apai, lies about 65 kilometers north of the Tongan capital of Nuku’alofa and lies within the so-called Tonga-Kermadec volcanic arc, a line of mostly submarine volcanoes that runs along the edge western pacific Plaque of Earth crust, Nature magazine reported.

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The eruption began on January 13, launching explosions that shattered the surface of the water and generated a major lightning strike, according to Reuters. Then, on January 15, rising magma from Hunga Tonga-Hunga Ha’apai met seawater above the volcano, triggering a sudden and massive explosion. Such explosive eruptions can occur when magma rapidly heats water to steam, which then rapidly expands; bubbles of volcanic gas captured in the magma also help push these dramatic explosions up and out of the water, Nature reported.

Underwater volcanic eruptions don’t usually release large plumes of gas and particles into the air, but the Jan. 15 eruption was an exception to that rule, Nature reported.

Two weather satellites – the National Oceanic and Atmospheric Administration’s Geostationary Operational Environmental Satellite 17 (GOES-17) and the Japan Aerospace Exploration Agency’s Himawari-8 – captured the unusual eruption from above, allowing scientists at NASA’s Langley Research Center to calculate how far the plume has penetrated the atmosphere.

“From the two angles of the satellites, we were able to recreate a three-dimensional image of the clouds,” Konstantin Khlopenkov, a NASA Langley team scientist, said in the statement.

They determined that at its highest point, the plume rose 58 km into the air, meaning it pierced the mesosphere – the third layer of the atmosphere – according to the NASA statement. . After an initial explosion generated this towering plume, a secondary explosion from the volcano sent ash, gas and steam more than 50 km into the air.

In 1991, Mount Pinatubo in the Philippines triggered a plume that extended 35 km above the volcano, and until the recent Hunga Tonga-Hunga Ha’apai eruption, this 1991 event held the record for the largest known volcanic plume in satellite recording, the statement noted.

When the highest parts of these plumes reached the mesosphere, they rapidly transitioned into a gaseous state. But in the stratosphere below, gas and ash from the volcano accumulated and spread to cover an area of ​​60,000 square miles (157,000 square kilometers).

This sequence of still images from GOES-17 shows the volcanic plume in different stages on January 15. (Image credit: NASA Earth Observatory images and video by Joshua Stevens, using data courtesy of Kristopher Bedka and Konstantin Khlopenkov/NASA Langley Research Center, and GOES-17 images provided courtesy of NOAA and the National Environmental Satellite, Data, and Information Service (NESDIS))

“As the plume from the eruption hit the stratosphere and spread outward, it appears to have created waves in the atmosphere,” Chris Vagasky, meteorologist at Vaisala, an environmental technology company, told Reuters. . Vagasky and his colleagues are still studying the lightning activity generated by the eruption, and he is interested in how these atmospheric waves influenced the pattern of lightning strikes.

To study lightning, the team uses data from GLD360, a ground-based lightning detection network operated by Vaisala. The data revealed that of the approximately 590,000 lightning strikes that occurred during the eruption, about 400,000 occurred within six hours of the large explosion on January 15, Reuters reported.

Prior to the Tonga eruption, the largest volcanic lightning event recorded by Vaisala occurred in Indonesia in 2018, when Anak Krakatau erupted and generated approximately 340,000 lightning strikes over the course of a week. “To detect nearly 400,000 in just a few hours is extraordinary,” Vagasky told Reuters. About 56% of the lightning struck the surface of the land or ocean, and more than 1,300 strikes landed on Tonga’s main island, Tongatapu, the team determined.

Lightning came in two flavors. One type of lightning was caused by a “dry charge”, in which ash, rocks and lava particles repeatedly collide in the air and exchange negative charges. electrons. The second type of lightning was caused by “ice charging,” which occurs when the volcanic plume reaches heights where water can freeze and form colliding ice particles, Reuters reported.

Both of these processes lead to lightning strikes by causing electrons to accumulate on the underside of clouds; these negatively charged particles then jump to higher, positively charged regions of the clouds or to positively charged regions of the ground or sea below.

“The percentage of lightning categorized as cloud-to-ground was higher than what you would normally see in a typical thunderstorm and higher than what you typically see in volcanic eruptions, which creates some interesting research questions,” Vagasky said. at Reuters.

Originally posted on Live Science.