A number of studies are being published by scientists on the Huge eruption of January 15th this year’s Hunga-Tonga Hunga-Ha’apai. Even in March, study had shown how the tsunami generated by the volcanic event had spread across the world. Now, several other studies shed more light on how the eruption was treated as a planetary event with seismic and infrasound measurements at various points in the world.
The shock waves generated by the eruption brought sudden variation of atmospheric pressure from South to North of Brazil and caused small tsunami off the Brazilian coast. The material released into the atmosphere during the eruption was also responsible for change sky colors in various areas of Brazil and brought pictures of spectacular evenings in the south of the country. In Argentina, the eruption generated noctilucent clouds in Patagonia.
O latest study about the eruption of Hunga-Tonga Hunga-Ha’apai is the cover of the 1st of July edition of the prestigious Science magazine. The work is signed by more than 70 scientists from various research centers. According to them, the volcano’s January 15, 2022 eruption produced an explosion in the atmosphere of “a size that has not been documented in the modern geophysical record.” The event generated a wide range of atmospheric waves observed globally by various terrestrial and space instrumentation networks.
The most intense propagated through four passes around the Earth over six days. As measured by wave amplitudes, “the explosion was comparable in size to the eruption of Krakatau in 1883,” experts said. According to them, the eruption of Hunga produced remarkable infrasound (0.01 to 20 hertz and could be heard 10 thousand kilometers away from the volcano with ionospheric disturbances detected globally.
Seismographs around the world report, record pure and coupled air-ground seismic waves. The air-sea coupling, say the authors of the work, probably contributed to fast-arriving tsunamis. “The eruption was a unusually energetic explosive event”, according to the study, with the gases reaching the stratosphere.
“The geophysical records of the Hunga eruption provide an unparalleled global dataset of atmospheric wave generation and propagation, offering an opportunity for multi-technology observation, modeling and validation unprecedented in the modern record. The eruption offers an even extraordinary opportunity to advance the understanding of physical phenomena that are rarely captured.”
Very little was known about the evolution of the Hunga-Tonga Hunga-Ha’apai volcano before the eruption on January 15th of this year. The first recorded observation of an eruption was in 1912, followed by another in 1937 and then 1988, 2009 and 2014-15. These eruptions were all small, the largest VEI-2 on the eruption scale, but with so few events there is no good understanding of the style of activity, says the Smithsonian.
The 1988 eruption was seen by fishermen and airline pilots, then analyzed by geologists. It occurred from three shallow water vents adjacent to the island of Hunga Ha’apai, but there was no island formed by the volcano. The eruption that began on March 17, 2009 had one vent at Hunga Ha’apai and another submerged about 100 meters offshore. The ejection of volcanic material filled the space between them in a few days, expanding the size of the island. After just four days, the 2009 eruption was over, but it stretched the island by a kilometer, leaving crater lakes emitting steam.
The next eruption took place from December 19, 2014 to January 28, 2015. This longer period of activity was centered between the islands of Hunga Tonga and Hunga Ha-apai and built a new island. Eventually, there was so much material that the islands were all connected.
On December 20, 2021, a new eruption produced a steam-rich plume of gas and ash that rose to 16 kilometers (52,500 ft) in altitude. After almost two weeks of lull, activity resumed with a high phreatomagmatic eruptive phase at the Hunga Tonga-Hunga Haʻapai volcano. A spectacular explosion occurred, characterized by dark, dense masses of pyroclastic material. An ever-larger, denser plume sent ash up to 55,000 feet (17,000 meters) altitude. On January 15th, the volcano had its biggest explosion and was a global event with a tsunami in the sea in the Pacific and a planetary shock wave that generated meteotsunami in other oceans of the planet.