The Hunga Tonga–Hunga Ha’apai Eruption of 15 January 2022: Observations on the International Monitoring System (IMS) Hydroacoustic Stations and Synergy with Seismic and Infrasound Sensors

Abstract

AbstractExamination of the International Monitoring System (IMS) hydroacoustic data recorded during the 15 January 2022 eruption of the Hunga Tonga–Hunga Ha’apai (HTHH) volcano shows that the in-water hydroacoustic sensors recorded a long-duration (40 min) activity starting before and ending after the paroxysmal HTHH eruption at about 4:15 UTC. The main eruption at 4:15 UTC simultaneously generated low-frequency [0.001–0.05] Hz seismic body waves and large infrasound waves in the atmosphere, as well as a tsunami. The peak-to-peak pressure observed at the closest IMS station, IS22, 1850 km away from the source, was 340 Pa, dwarfing the largest previously observed record for the signal from the Chelyabinsk meteor. The infrasound waves included a Lamb wave containing periods at least up to 2000 s. The Lamb wave and tsunami are well recorded on infrasound and near-shore seismometers. The air wave generated a precursor tsunami ahead of the main tsunami, but we do not observe it on the hydroacoustic IMS network. The dispersive tail of the main tsunami is observed on four in-water hydroacoustic hydrophone stations, one of them as far as 16,120 km away in the Atlantic Ocean.