GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.2 GNGTS 2024 Multscale Analysis of Physical Rock Propertes at Stromboli Volcano: What controls the frictonal propertes? S.C. Vinciguerra 1 , T. Alcock 2 , P.B. Benson 2 1 Department of Earth Sciences, University of Turin, Italy 2 School of Earth and Environmental Sciences University of Portsmouth, England The physical, mechanical and fracture propertes at Stromboli volcano have been integrated at multple scales to understand whether the interplay between a presumed NE/SW rif zone and the Sciara del Fuoco (SDF) depression has resulted in a zone of weakness able to promote fracturing prone to fank instability (Tibaldi et al., 2004; Alcock et al., 2024). Multscale fracture quantfcaton by imaging via FracPaQ toolbox both fractures and sample scale fractures has been integrated with rock physics and rock mechanics experiments on cm samples belonging to the Paleostromboli, Vancori, Neostromboli, Pizzo and Present Deposit volcanic cycles that have been taken from within and outside the rif zone. The structural changes to the edifce have been quanttvely assessed by mapping at diferent scale fracture propertes such density and orientaton within and outside the rif zone allowing to identfy the potental damaged zones that could reduce the edifce strength. Results indicate that basalt textures, microfracture density, porosity, chemical zoning and preferental alignments, despite lithologically dependent, can be related to the NE/SW zone of weakness at the regional scale and to collapsed volumes that have been subject to contnuous intrusive actvity. Numerical inversion models have been performed to cross correlate fracture density in the basalts at multple scales. A link between microfracture density and seismic velocites has been also established via numerical modelling, allowing to interpret in terms of degree of fracturing the results of seismic tomographies at the feld scale, providing a novel method to image crack damage evoluton within the inner structure of the volcano edifce. In order to image and constrain the fracturing mechanisms controlling the initaton of rupture in the instable sector of SDF in Stromboli a multscale approach has been consequently designed by frst identfying and analyzing via satellite fractures and then exploring via laboratory experiments how the initaton of rupture and the frictonal propertes evolve under diferent loading conditons, pore fuid content and efectve pressure. An inital assessment on the potental frictonal propertes was performed by determining the slip tendency (Ts) from 2-D Imagery and sampling lithological units according to the remote sensing analysis and the locaton with respect