GNGTS 2022 - Atti del 40° Convegno Nazionale

GNGTS 2022 Sessione 1.2 123 ANALYSIS OF EFFUSION RATE ON MT ETNA FLANK ERUPTIONS AND THEIR IMPACT IN ASSESSING THE LAVA FLOW HAZARDS F. Zuccarello, G. Bilotta, A. Cappello, G. Ganci Istituto Nazionale Di Geofisica E Vulcanologia, Catania, Italy The rate at which lava is discharged plays a key role in controlling the distance covered by lava flows fromeruptive vents among other physical factors (e.g., melt compositions, water content, lava viscosity, heat loss, topography of the terrain), and it constitutes a critical parameter for the physical-mathematical modelling of lava flows. Generally, lava effusion rate changes over time, but both for assessing long-term hazards and for real-time monitoring during on-going eruptions, the effusion rate has been assumed to be constant or to have a bell-shaped time- dependent behavior. Here, we investigated available time averaged discharge rates (TADRs) derived from field measurements and satellite thermal imagery for recent eruptions at Mt. Etna volcano (Italy), in order to define a possible generalized effusion rate trend to be used for simulating lava flow paths. Only flank eruptions were selected for this study, which represent the major source of hazard for the densely populated areas around the volcano. TADRs temporal series were normalized to obtain homogeneous curves in duration and sampling times, reducing redundancies and improving data consistency. Our data indicate a fast waxing phase where effusion rate peaks occur between the 0.5 and 29% of the total eruption time, then followed by a progressive decrease in the waning phase. Three characteristic curves have been built by calculating the 25 th , 50 th and 75 th percentiles associated to the occurrence of effusion rate peaks and to the slope variations of descending curves in the waning phase. Finally, these characteristic curves have been used to run numerical tests by means of the physics-based GPUFLOW model. Our tests showed how the different characteristic effusion rate curves can impact single vent scenarios, as well as on short- and long-term hazard maps. Statistics on the final emplacements revealed variations up to 40%, confirming the key role of the effusion rate in controlling the development of lava flow fields.