Infrasound associated with the eruption of the Hunga volcano

Area of Science:

• Geophysics
• Atmospheric Science
• Seismology

Background:

• The 2022 Hunga Tonga-Hunga Ha'apai eruption produced significant infrasonic waves.
• Infrasound stations in China detected signals with unexpectedly high amplitudes.
• Standard absorption models failed to predict these amplitudes due to unconsidered thermospheric effects.

Purpose of the Study:

• To investigate the reasons for the high amplitude of infrasound waves detected far from the Hunga Tonga-Hunga Ha'apai eruption.
• To analyze the impact of thermospheric dispersion on the propagation of volcanic infrasound.

Main Methods:

• Simulating dispersive sound speeds and attenuation coefficients at various frequencies using theoretical models and experimental data.
• Analyzing the influence of thermospheric dispersion on infrasound wave propagation paths.

Main Results:

• Thermospheric dispersion significantly alters sound speed, affecting far-field wave propagation.
• While abnormal attenuation coefficients have a smaller impact, they also contribute to observed signal amplitudes.
• The study explains the large amplitude of thermospheric infrasound signals received in China.

Conclusions:

• Thermospheric dispersion is a critical factor in understanding the propagation of powerful infrasound waves from volcanic eruptions.
• Accurate modeling of infrasound propagation requires incorporating dispersion effects in the thermosphere.
• This research clarifies the anomalous detection of Hunga Tonga-Hunga Ha'apai eruption infrasound signals.