GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.2 GNGTS 2023 How much did Etna's summit change? The new hazard from lava flow inundation F. Zuccarello, G. Bilotta, A. Cappello, G. Ganci Istituto Nazionale Di Geofisica E Vulcanologia , Catania, Italy Lava flows are the most common hazard in active basaltic volcanoes, which may impact human infrastructures causing significant economic damage. Hazard maps outline the areas with the highest probabilities of inundation, thus representing a useful tool for mitigation actions and land use planning. In this study, we present a new hazard map linked to the inundation of lava flows at the summit of Mt. Etna volcano (Italy), which is one of the most active basaltic volcanoes in the world, where an almost persistent activity characterizes the summit area, alternated with flank eruptions. High-energy explosive activity coupled with a high rate of lava effusion took place at the main vents located at summit, as observed during the recent 2020-2022 paroxysmal activity. Occasionally, emission of lava flows may occur in vents located close to the summit that are fed directly by the central conduits as during the July 2014, February-April 2017, May-July 2019 and May-June 2022 eruptions. The intense eruptive activity in the last decades, which interested mainly the South East Crater (SEC), posed the need to develop an updated hazard map that considers the morphological changes of the summit area induced by the emplacements of lava flows and pyroclastic deposits. Our hazard map has been obtained through a probabilistic approach that integrates the numerical simulations of lava flows on a 2022 Digital Terrain Model (DTM) with statistical analyses of the volcanological historical data. The probabilistic approach includes: i) the estimation of the spatiotemporal probability of future vent opening; ii) the calculation of the occurrence probability of the eruptive classes, given by the distribution of volume of lava erupted and durations of eruptions; iii) the simulation of the lava flow paths for all defined eruptive classes from each potential vents using the GPUFLOW model; iv) the mapping of the probability of inundation by combining the numerical simulations with the probability of future vent opening and the occurrence probability. The potential vents have been defined over an area corresponding to the Ellittico caldera, while the eruptive classes have been derived by considering both the short- and long-lasting eruptions that occurred at Etna’s summit since 1998, for which max fluxes emitted at potential vents over time are consistent with the eruptive dynamics observed. The obtained map shows a very high probability of inundation of lava flows emitted at vents linked to the SEC, according to the observation of the eruptive dynamics in the last decades.