On Tsunami Waves Induced by Atmospheric Pressure Shock Waves after the 2022 Hunga Tonga-Hunga Ha'apai Volcano Eruption

Employing a linear shallow water equation (LSWE) model in the spherical coordinates, this paper investigates the tsunami waves generated by the atmospheric pressure shock waves due to the explosion of the submarine volcano Hunga Tonga-Hunga Ha'apai on 15 January 2022. Using the selected 59 atmospheric pressure records in the Pacific Ocean, an empirical atmospheric pressure model is first constructed. Applying the atmospheric pressure model and realistic bathymetric data in the LSWE model, tsunami generation and propagation are simulated in the Pacific Ocean. The numerical results show clearly the co-existence of the leading locked waves, propagating with the speed of the atmospheric pressure waves (similar to 1,100 km/hr), and the trailing free waves, propagating with long gravity ocean wave celerity (similar to 750 km/hr). During the event, tsunamis were reported by 41 Deep-ocean Assessment and Reporting of Tsunamis (DART) buoys in the Pacific Ocean, which require corrections because of the occurrence of atmospheric pressure waves. The numerically simulated tsunami arrival time and the amplitudes of the wave crest and trough of the leading locked waves compare reasonably well with the corrected DART measurements. The comparisons for the trailing waves are less satisfactory, since free waves could also have been generated by other tsunami generation mechanisms, which have not been considered in the present model, and by the scattering of locked waves over changing bathymetry. In this regard, the numerical results show clearly that the deep Tonga trench (similar to 10 km) amplifies the trailing waves in the Southeast part of the Pacific Ocean via the Proudman resonance condition. Plain Language Summary On 15 January 2022, the eruption of the submarine volcano Hunga Tonga-Hunga Ha'apai, the largest volcano eruption in recent centuries, produced worldwide atmospheric pressure fluctuations and tsunami waves. In this paper we produced a simple model for atmospheric pressure in the Pacific Ocean based on selected pressure recordings. Based on this pressure model and realistic ocean depth data, we simulate the tsunami generation and propagation in the Pacific Ocean. We found that the explosion shock wave induced by the volcanic eruption is the main mechanism for tsunami generation. Two separate tsunami waves, traveling at different speeds, can be distinguished. Additional tsunami waves are also generated when the pressure wave travels over steep deep ocean features such as the Tonga Trench, leading to significantly larger waves in the Southeast part of the Pacific Ocean.