ROLE OF LAMB WAVE AND ATMOSPHERIC GRAVITY WAVE FOR THE 2022 HUNGA TONGA-HUNGA HAʻAPAI METEOTSUNAMIS

On January 15, 2022, a massive eruption occurred at the Hunga Tonga-Hunga Ha’apai volcano in the Tonga islands, South Pacific Ocean. The eruption resulted in rapid atmospheric pressure changes and tsunamis along the Pacific coast. Along the coast of Japan, tsunami waves were observed several hours earlier than the expected arrival time due to the pressure change of about 2 hPa, and the subsequent tsunami heights exceeded 1 m at several tide stations. These surface fluctuations were categorized as meteotsunamis, in which the sea surface is excited by atmospheric pressure. Proudman resonance and bay oscillations were assumed to contribute to the amplification, but the factors which caused the large amplification off the coast of Japan are not clarified. This study aims to estimate the primary factors of the maximum tsunami amplitude in Japan by comparing numerical simulations under multiple atmospheric pressure wave conditions with the observation records by Japan Meteorological Agency (JMA) and Ports and Harbours Bureau, MLIT.