What excited tsunami from Tonga 2022 eruption? Observation and theory

Abstract Tsunamis are commonly generated by earthquakes beneath the ocean floor, volcanic eruptions, and landslides. The mysterious tsunami following the Tonga eruption of 2022 is believed to be excited by the atmospheric pressure fluctuations generated by the explosion of this volcano. However, it is not clarified observationally and theoretically that which atmospheric fluctuations excited the tsunami. We show the atmospheric waves that possibly excited the tsunami based on observations detected by our own-manufactured sensors in Japan. The atmospheric fluctuations are classified into Lamb waves, acoustic waves, and gravity waves. The arrival time of the gravity wave and atmosphere-ocean coupling simulation show that the gravity wave propagated at a phase speed of 200-220 m/s, coinciding with tsunami velocity in the Pacific Ocean and suggesting that the gravity wave resonantly excited the tsunami (Proudman resonance). These observations and theory provide an essential basis for theoretical investigations of volcano-induced meteo-tsunamis, including the Tonga event.