The 15 January 2022 Event at Hunga Tonga-Hunga Ha'apai, Recorded by Multiparametric Stations in Italy

Abstract

The eruption of the volcano Hunga Tonga-Hunga Ha‘apai on Jan 15, 2022, 04:14:54 UTC, was such energetic that instruments observed different physical phenomena all over the globe. In Italy, the Istituto Nazionale di Geofisica e Vulcanologia (INGV), who is continuously operating different kinds of monitoring networks, as e.g., the Italian Seismic Network (ISN), micro-barometric and infrasonic stations for monitoring the active volcanoes, ionospheric monitoring network (GNSS and ionosonde), recorded seismic, acoustic and electromagnetic signals originated by this exceptional event. The blast wave generated by the volcanic explosion of Hunga Tunga was recorded by the micro-barometric and infrasound stations installed at Phlegrean Fields (PF), at Stromboli volcano and on Mt. Etna. The first arrival was recorded at ~20:00 UTC, after travelling along the “short” great circle (17600 km), was succeeded by a second onset, about 3:40 h later, arriving at PF from the opposite direction. The mean propagation velocity in both directions was calculated as 310 m/s. The stations of the Etna Radio Observatory (ERO) are also equipped with micro-barometers, measuring the atmospheric pressure at a sampling rate of 5 min. The first group of atmospheric shock waves was recorded in the evening of Jan 15, 2022, while 36 hours later the ERO-stations observed a second signal after having completed the second orbit. The magnitude of M5.7 of the Hunga Tonga eruption was strong enough to record core phases (PKIKP, PKP), surface reflection of mantle phases (PP, SS), as well as Rayleigh and Love waves, at many stations of the ISN. The atmospheric waves generated by the eruption generated Travelling Ionospheric Disturbances in the ionosphere detected as disturbances in the Total Electron Content calculated by using GNSS data acquired by the GNSS network of INGV and variations of the ionospheric peak layer parameters (foF2, hmF2), recorded by the ionosonde installed on the Italian territory by INGV.