An unconventional tsunami: 2022 Tonga event

Abstract

On January 15, 2022, a powerful eruption occurred at Honga Tonga-Hunga Ha'apai volcano, Tonga, and a tsunami was generated to propagate across the Pacific Ocean. The recorded tsunami waves were both earlier and more destructive than predicted by the conventional tsunami models. In this study, we investigate the underlying mechanism of this tsunami event, which is confirmed to be a combination of the atmospheric forcing, the volcanic eruption and the local resonance. Our numerical results show that the atmospheric pressure variations induced by the volcano eruption generated early waves with small amplitudes of about 0.1 m, while the volcano eruption as a direct source, with a duration of 8 min and an ejected volume of 0.3 km3, triggered large waves propagating across the South Pacific Ocean with amplitudes of about 0.5 m. In addition, the local resonance effect resulted in extreme waves with amplitude of 0.8-1.7 m in the coastal regions. These results reasonably explain the observed facts, confirming that the 2022 Tonga tsunami was an unconventional event.