Mechanism of a meteorological tsunami reaching the Japanese coast caused by Lamb and Pekeris waves generated by the 2022 Tonga eruption

Tide gauge data indicated that ocean waves were generated by the eruption of the Hunga Tonga-Hunga Ha'apai volcano on January 15, 2022. These high-amplitude waves reached the Japanese coast earlier than expected for free ocean waves. These fluctuations in sea level were reasonably reproduced by an ocean model, with realistic bottom topography forced by sea-level pressure perturbations well reproduced by atmospheric general circulation models. While early arrival times are associated with atmospheric Lamb waves, the amplitude of the sea level changes cannot be fully explained by the resonance mechanism associated with sea-level pressure fluctuations of Lamb and Pekeris waves alone. Rather, resonance due to atmospheric waves in conjunction with the amplification effects caused by a steep continental slope is required in order to reproduce sea level fluctuations along the Japanese coast. In particular, the deep Northwest Pacific Basin to the east of Japan is important for strengthening the amplitude of the meteorological tsunami.

Automated summary

Tide gauge data showed that the eruption of the Hunga Tonga-Hunga Ha'apai volcano on January 15, 2022 generated ocean waves. These waves reached the Japanese coast earlier than expected and were reasonably reproduced by an ocean model with realistic bottom topography and atmospheric general circulation models. The amplitude of the sea level changes cannot be fully explained by pressure fluctuations alone, but rather require resonance due to atmospheric waves and amplification effects caused by a steep continental slope.