Observation and simulation of atmospheric gravity waves exciting subsequent tsunami along the coastline of Japan after Tonga explosion event

Abstract

Tsunamis are commonly generated by earthquakes beneath the ocean floor, volcanic eruptions, and landslides. The tsunami following the Tonga eruption of 2022 is believed to have been excited by atmospheric pressure fluctuations generated by the explosion of the volcano. The first, fast-traveling tsunami was excited by Lamb waves; however, it has not been clarified observationally or theoretically which type of atmospheric fluctuations excited more prominent tsunami which followd. In this study, we investigate atmospheric gravity waves that possibly excited the aforementioned subsequent tsunami based on observations and atmosphere-ocean coupling simulations. The atmospheric fluctuations are classified as Lamb waves, acoustic waves, or gravity waves. The arrival time of the gravity wave and the simulation shows that the gravity wave propagated at a phase speed of 215 m/s, coinciding with the tsunami velocity in the Pacific Ocean, and suggesting that the gravity wave resonantly excited the tsunami (Proudman resonance). These observations and theoretical calculations provide an essential basis for investigations of volcano-induced meteotsunamis, including the Tonga event.

Simulation study of atmosphere–ionosphere variations driven by the eruption of Hunga Tonga-Hunga Ha’apai on 15 January 2022

“…Numerous observational studies have already been done about the HTHH volcanic eruption event, and various important phenomena in the study of the atmospheric and ionospheric disturbances have been discovered: (1) Lamb waves and gravity waves concentrically propagating from the HTHH volcano (Amores et al 2022;Matoza et al 2022;Nishikawa et al 2022;Omira et al 2022;Suzuki et al 2023;Tanioka et al 2022;Watanabe et al 2022;Wright et al 2022;Yamada et al 2022;Madonia et al 2023); (2) traveling ionospheric disturbances (TIDs) associated with atmospheric waves triggered by the eruption (e.g., Saito 2022; Zhang et al 2022;Shinbori et al 2022;Chen et al 2022;Ghent and Crowell 2022;Themens et al (2022); Lin et al 2022;Verhulst et al 2022;Li et al 2023b;Heki 2022;Han et al 2023;Liu et al 2023b); (3) significant variations in total electron content (TEC) near the eruption region (Aa et al 2022a;Astafyeva et al 2022;Sun et al 2022b;He et al 2023); (4) TIDs in the magnetically conjugate region connected with HTHH region possibly driven by the electric field (e.g., Saito 2022; Shinbori et al 2022;Lin et al 2022); (5) short-period oscillations in the geomagnetic field (e.g., Iyemori et al 2022;Yamazaki et al 2022;Schnepf et al 2022;Zhang et al 2022;Kong et al 2022); (6) global thermospheric wind variations after the eruption (e.g., Harding et al 2022;Li et al 2023a...…”

“…One of the most prominent phenomena in the atmosphere in this event is generation and propagation of Lamb waves triggered by the explosive eruption. Various numerical simulations have been performed using global atmospheric models (Amores et al 2022;Watanabe et al 2022;Nishikawa et al 2022), and successfully reproduced the propagation of Lamb waves. Besides Lamb waves, Watanabe et al (2022) detected Pekeris waves by analyzing data taken from the Himawari-8 geostationary satellite for the first time.…”

Simulation study of atmosphere-ionosphere variations driven by the eruption of Hunga Tonga-Hunga Ha'apai on 15 January 2022

“…Numerous observational studies have already been done about the HTHH volcanic eruption event, and various important phenomena in the study of the atmospheric and ionospheric disturbances have been discovered: (1) Lamb waves and gravity waves concentrically propagating from the HTHH volcano (Amores et al 2022;Matoza et al 2022;Nishikawa et al 2022;Omira et al 2022;Suzuki et al 2022;Tanioka et al 2022;Watanabe et al 2022;Wright et al 2022;Yamada et al 2022;Madonia et al 2023), (2) traveling ionospheric disturbances (TIDs) associated with atmospheric waves triggered by the eruption (e.g., Saito 2022;Zhang et al 2022;Shinbori et al 2022;Chen et al 2022;Ghent et al 2022;Themens et al (2022); Lin et al 2022;Verhulst et al 2022;Li et al 2023b;Heki 2022;Han et al 2023;Liu et al 2023b),…”