[U-09] Submarine volcanic eruption in Tonga accompanied by a meteo-tsunami

[U09-05] Identification of atmospheric waves from the 2022 Tonga volcano eruption by KUT infrasound network observations.

*Yasuhiro Nishikawa¹, Masa-yuki Yamamoto¹, Kensuke Nakajima², Hiroaki Saito³, Yoshihiro Kakinami⁴, Islam Hamama¹ (1.Kochi University of technology. School of System Engoneering., 2.Kyushu University. Faculty of Sciences., 3.Hokkaido University. Department of Cosmosciences., 4.Hokkaido Information University. Space Information Center.)

Keywords:Lamb wave, Gravity wave, Avoustic wave

When a volcano erupts, the explosion causes a change in atmospheric pressure, and the airwaves can be observed at a distance. Significant volcanic eruptions excite airwaves with large amplitude and wavelength, reaching farther. The giant eruption at the Hunga Tonga-Hunga Ha’apai volcano in Tonga on January 15, 2022 (Volcanic Explosivity Index 6), generated the shock waves that reached Japan, about 8,000 km away, as an airwave. Barometers observed the airwave as an air pressure change. The change in air pressure was also monitored by the infrasound sensors (microbarometers) installed throughout Japan by the Kochi University of Technology (KUT). The recorded signals can be categorized as Lamb waves (low-frequency acoustic-gravity), acoustic waves, and gravity waves. We analyze the pressure fluctuations measured by the KUT infrasound sensors and identify that the pressure wave generated by the eruption contains three types of pressure sound waves: Lamb wave, acoustic waves, and gravity wave. The Lamb and gravity surface-guided waves propagated directly from Tonga to Japan, and each acoustic wave propagated through the stratosphere and thermosphere. We suggest their wave celerity and paths by observations and simulations.