An Antipodal Seismic and (Infra)acoustic View from Central Europe on the 15 January 2022 Hunga–Tonga–Hunga–Ha’apai Eruption

Abstract

Abstract We present seismic and (infra)acoustic observations of the 15 January 2022 Hunga–Tonga–Hunga–Ha’apai (HTHH) eruption from Switzerland and central Europe at epicentral distances around 153°. Our observations indicate that the efficient seismoacoustic coupling of locally confined atmospheric oscillations (at the volcanic plume) and long-reaching (global) atmospheric waves at frequencies around 4 mHz is responsible for the global seismic reach of the HTHH eruption at low frequencies. At high frequencies (HFs), we recorded many short impulsive seismoacoustic signals with frequencies well above 20 Hz. They coincided with the passage of the HF part of the rather low-frequency atmospheric wave and triggered numerous false local-earthquake detections on the Swiss monitoring system. Simultaneous reliable ear witness reports of thunderlike sounds from southwest Germany suggest that signals related to the eruption were audible in central Europe at a distance of more than 17,000 km from HTHH. We postulate that the source of these HF seismoacoustic signals was the vigorous volcanic lightning activity observed at HTHH.