Hunga Tonga Erupts

The massive eruption of the Hunga volcano created an atmospheric pulse that caused an unusual tsunami-like disturbance

This looping video shows a series of GOES-17 satellite images that captured an umbrella cloud generated by the submarine eruption of the Hunga Tonga-Hunga Ha’apai volcano on January 15, 2022. Arcing shock waves shaped of crescent and many flashes are also visible. Credit: NASA Earth Observatory image by Joshua Stevens using GOES imagery courtesy of NOAA and NESDIS

Hunga Volcano Eruption Provides Data Blast

The gigantic January 15, 2022, eruption of Hunga Underwater Volcano in the South Pacific Ocean devastated the island nation of Tonga and created a variety of atmospheric wave types, including booms heard 6,200 miles (10,000 km) away in Alaska. It also created an atmospheric pulse that caused an unusual tsunami-like disturbance that arrived on Pacific shores earlier than the actual tsunami.

These are among the many sightings reported by a team of 76 scientists from 17 countries who studied the atmospheric waves of the eruption, the the greatest known of a volcano since 1883 Krakatoa Eruption. The team’s work, compiled in an unusually short time frame due to significant scientific interest in the eruption, was published May 12, 2022 in the journal Science.

David Fee, director of the Wilson Alaska Technical Center at the University of Alaska Fairbanks Geophysical Institute, is a lead author of the research paper and among four of the center’s scientists involved in the research.

Eruption of Hunga Tonga NASA GOES 17 Satellite

The image of the Hunga eruption is from the National Oceanic and Atmospheric Administration’s GOES-17 satellite. Credit: NOAA

The eruption of Hunga, near the island of Tonga, provided unprecedented information on the behavior of certain atmospheric waves. A dense network of barometers, infrasound sensors, and seismometers in Alaska – operated by the Geophysical Institute’s Wilson Technical Center, Alaska Volcano Observatory, and Earthquake Center of Alaska – contributed data.

“Our hope is that we will be better able to monitor volcanic eruptions and tsunamis by understanding the atmospheric waves from that eruption,” said Fee, who is also the coordinating scientist. at the Geophysical Institute portion of the Alaska Volcano Observatory.

“Atmospheric waves have been recorded globally over a wide band of frequencies, and by studying this remarkable dataset, we will better understand the generation, propagation and recording of acoustic and atmospheric waves,” he said. -he declares. “This has implications for monitoring nuclear explosions, volcanoes, earthquakes and various other phenomena.”

Hunga Volcano Data

The top image shows the locations of the instruments that provided data. The red and blue pattern around the Hunga volcano is a snapshot image from a weather satellite showing the atmospheric disturbance created by the Lamb wave. The bottom image shows two months of Hunga activity. Credit: David Fee

The researchers found particularly interesting the behavior of the flare’s Lamb wave, a type named after its 1917 discoverer, English mathematician Horace Lamb.

Larger atmospheric explosions, such as volcanic eruptions and nuclear tests, create Lamb waves. They can last from a few minutes to several hours.

A Lamb wave is a type of guided wave, one that travels parallel along the surface of a material and also extends upward. With the Hunga eruption, the wave traveled along the Earth’s surface and circled the planet four times in one direction and three times in the opposite direction – the same as seen during the eruption. eruption of Krakatau in 1883.

“Lamb waves are rare. We have very few high-quality observations of them,” Fee said. “By understanding the Lamb wave, we can better understand the source and the eruption. It is related to the tsunami and the generation of the volcanic plume and is also likely related to the high frequency infrasound and acoustic waves of the eruption.

Stereoscopic observations of the Tonga volcano plume

A NASA satellite captured the explosive Hunga Tonga-Hunga Ha’apai eruption in the South Pacific. Credit: Image by Joshua Stevens/NASA Earth Observatory, using GOES-17 imagery courtesy of National Oceanic and Atmospheric Administration and National Environmental Satellite, Data and Information Service

The Lamb wave consisted of at least two pulses near Hunga, the first having a seven to 10 minute pressure rise followed by a second larger compression and a subsequent long pressure drop.

The wave also reached Earth’s ionosphere, rising at 700 mph at an altitude of about 280 miles, according to data from ground stations.

A major difference between the Lamb wave from the Hunga explosion and the 1883 wave is the amount of data collected due to more than a century of technological advances and a proliferation of sensors around the world, according to the article.

Scientists noted other findings about atmospheric waves associated with the eruption, including “remarkable” long-range infrasound – sounds too low in frequency for humans to hear. Infrasound arrived after the Lamb wave and was followed by audible sounds in some regions.

The audible sounds, the paper notes, traveled about 6,200 miles to Alaska, where they were heard across the state as repeated booms about nine hours after the eruption.

“I heard the sounds, but at the time I certainly didn’t think it was from a volcanic eruption in the South Pacific,” Fee said.

The Alaskan reports are the furthest documented accounts of audible sound from its source. This is due in part, the paper notes, to the increase in the world’s population and advances in societal connectivity.

“We will study these signals for years to find out how the atmospheric waves were generated and how they propagated so well through the Earth,” Fee said.

Reference: “Atmospheric waves and global seismoacoustic observations of the January 2022 eruption at Hunga, Tonga” by Robin S. Matoza, David Fee, Jelle D. Assink, Alexandra M. Iezzi, David N. Green, Keehoon Kim, Liam Toney , Thomas Lecocq, Siddharth Krishnamoorthy, Jean-Marie Lalande, Kiwamu Nishida, Kent L. Gee, Matthew M. Haney, Hugo D. Ortiz, Quentin Brissaud, Léo Martire, Lucie Rolland, Panagiotis Vergados, Alexandra Nippress, Junghyun Park, Shahar Shani -Kadmiel, Alex Witsil, Stephen Arrowsmith, Corentin Caudron, Shingo Watada, Anna B. Perttu, Benoit Taisne, Pierrick Mialle, Alexis Le Pichon, Julien Vergoz, Patrick Hupe, Philip S. Blom, Roger Waxler, Silvio De Angelis, Jonathan B Snively, Adam T. Ringler, Robert E. Anthony, Arthur D. Jolly, Geoff Kilgour, Gil Averbuch, Maurizio Ripepe, Mie Ichihara, Alejandra Arciniega-Ceballos, Elvira Astafyeva, Lars Ceranna, Sandrine Cevuard, Il-Young Che, Rodrigo De Negri, Carl W. Ebeling, Läslo G. Evers, Luis E. Franco-Marin, Thomas B. Gabrielson, Katrin Hafner, R. Giles Harrison, Attila Komjathy, Giorgio Lacanna, John Lyons, Kenneth A. Macpherson, Emanuele Marchetti, Kathleen F. McKee, Robert J. Mellors, Gerardo Mendo-Pérez, T. Dylan Mikesell, Edhah Munaibari, Mayra Oyola -Merced, Iseul Park, Christoph Pilger, Cristina Ramos, Mario C. Ruiz, Roberto Sabatini, Hans F. Schwaiger, Dorianne Tailpied, Carrick Talmadge, Jérôme Vidot, Jeremy Webster and David C. Wilson, May 12, 2022, Science.
DOI: 10.1126/science.abo7063

Other Geophysical Institute scientists involved in research include graduate student Liam Toney, acoustic wave analysis, figure and animation production; postdoctoral researcher Alex Witsil, acoustic wave analysis and equivalent explosive yield analysis; and seismo-acoustic researcher Kenneth A. Macpherson, sensor response and data quality. All are with the Wilson Alaska Technical Center.

The Alaska Volcano Observatory, National Science Foundation, and US Defense Threat Reduction Agency funded the UAF portion of the research.

Robin S. Matoza of the University of California, Santa Barbara is the lead author of the paper.

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