MADRID, 20 Sep. (EUROPA PRESS) –
The catastrophic eruption of the Hunga Tonga-Hunga Ha’apai volcano in 2022 triggered a special atmospheric wave that has eluded detection for the last 85 years.
Researchers from the University of Hawaii at Manoa, the Japan Agency for Terrestrial and Marine Sciences and Technologies (JAMSTEC), and Kyoto University relied on state-of-the-art observational data and computer simulations to discover the existence of Pekeris waves: fluctuations in air pressure that were theorized in 1937 but they have never been shown to occur in nature, until now.
The study was published in the Journal of the Atmospheric Sciences.
The eruption in the South Pacific earlier this year launched what was probably the most powerful explosion the world has experienced since the famous 1883 eruption of Mount Krakatoa in Indonesia. The rapid release of energy excited pressure waves in the atmosphere that quickly spread across the globe.
The atmospheric wave pattern near the eruption was quite complicated, but thousands of kilometers away, the disturbances were caused by an isolated wavefront traveling horizontally at more than 650 kilometers per hour as it spread outward. The air pressure disturbances associated with the initial wavefront were clearly seen in thousands of barometer recordings around the world.
“The same behavior was observed following the Krakatau eruption, and in the early 20th century, the English scientist Horace Lamb developed a physical theory for this wave,” he said. it’s a statement Kevin Hamilton, professor emeritus of atmospheric sciences at UH Manoa.
“These motions are now known as Lamb waves. In 1937, the American-Israeli mathematician and geophysicist Chaim Pekeris extended Lamb’s theoretical treatment and concluded that a second-wave solution with a slower horizontal velocity should also be possible. Pekeris tried to find evidence for its slower wave in pressure observations following the Krakatoa eruption, but failed to produce a convincing case.”
Scientists applied a wide range of tools now available, including geostationary satellite observations, computer simulations, and extremely dense networks of air pressure observations, to successfully identify the Pekeris wave in the atmosphere following the Tonga eruption.
Lead author Shingo Watanabe, deputy director of the Environmental Modeling Research Center at the Japan Agency for Marine and Earth Sciences and Technologies, conducted computer simulations of the response to the Tonga eruption.
“When we investigated computer-observed and simulated pulses across the Pacific Rim, we found that the slower wavefront might be seen over wide regions. and that its properties coincided with those predicted by Pekeris nearly a century ago,” Hamilton said.
