GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.3 GNGTS 2024 Investgatng the Tonga-Kermadec subducton zone from the study of the preparaton phase of the June 15 2019 M7.2 Kermadec Islands (New Zealand) earthquake and the January 15 2022 Hunga Tonga-Hunga Ha’apai erupton Serena D’Arcangelo, Mauro Regi, Angelo De Sants, Loredana Perrone, Gianfranco Cianchini, Maurizio Soldani, Alessandro Piscini, Cristano Fidani, Dario Sabbagh, Stefania Lepidi, Domenico Di Mauro The Tonga-Kermadec zone is one of the most actve areas for the subducton contnuous processes characterizing the area. In the recent few years, it was afected by two important geophysical events: frst a strong earthquake of M7.2 on June 15 2019 with the epicentre in Kermadec Islands (New Zealand) and then an exceptonal erupton of Hunga Tonga-Hunga Ha’apai volcano on January 15 2022. In order to beter understand the geodynamics on the subducton area, we conducted a mult-parametric and mult-layer study on the phenomena occurred before both events basing on the lithosphere-atmosphere-ionosphere coupling (LAIC) models. We started with a seismic analysis of the earthquake sequence previous the June 15 2019 mainshock and of those antcipated the unique erupton, focusing on the circular area major afected to the preparaton phase, i.e., the one defned by the Dobrovolsky strain radius. Afer that, we focused our atenton on the atmospheric parameters generally infuenced by seismic and volcanic events (skin temperature, outgoing longwave radiaton, aerosol optcal depth, and so on) applying the CAPRI algorithm to the ECMWF datasets to detect anomalies in their values. At the end, using the satellite data we studied the magnetc feld and electron burst precipitatons, looking for precursors of both events considered. All these observatons together with their similarites and diferences provide a beter insight of the complex tectonic context. In conclusion, we reported evidence of the thermodynamic interacton between a stf lithosphere and a more malleable asthenosphere inside the Kermadec-Tonga region. The presence of two distnct types of coupling among the geolayers was also proposed to explain the observed results.