Source: Geophysical Research Letters
On 15 January 2022, the underwater Hunga Tonga–Hunga Ha‘apai volcano erupted between two uninhabited islands in the South Pacific’s Kingdom of Tonga. The one-in-a-thousand-year blast, whose plume reached 30 kilometers (nearly 19 miles) high, also rippled atmospheric waves around the globe. Sensors detected inertia gravity waves, infrasound waves, and Rossby waves near the eruption site. Farther afield, NASA satellites picked up Lamb waves repeatedly circling the Earth.
In a new study, Amores et al. simulate the air pressure waves propagated by the eruption in an effort to confirm that the Hunga Tonga–Hunga Ha‘apai eruption generated Lamb waves bouncing around the planet. They used a shallow-water oceanic model to model the atmospheric waves.
The simulation results showed excellent agreement with satellite and in situ observations of Lamb waves that moved around the globe. The authors noted that when compared to atmospheric pressure records, the model outputs were remarkably accurate in matching the arrival time of the pressure waves at different sensors. The results confirmed that the surface oscillations following the eruption did originate from the volcano.
Despite the limitations imposed by using an ocean model to simulate atmospheric waves, the approach aptly captured the main physical mechanisms of the Lamb waves, according to the authors. The methods showed how an ocean model could model the propagation of Lamb waves through the atmosphere following future volcanic perturbations. (Geophysical Research Letters, https://doi.org/10.1029/2022GL098240, 2022)
—Aaron Sidder, Science Writer