GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 A re-analysis of micro-earthquakes for characterising debated faults in the Esaro valley (Northern Calabria) H. Fernandez 1,2 , G. D. Chiappeta 1 , A. Schibuola 1,3 , M. La Rocca 4 , S. Gentli 1 , L. Peruzza 1 1 OGS, Trieste, Italy 2 Università degli Studi "G. d'Annunzio" Chiet - Pescara, Italy 3 Université Gustave Eifel, Marne-la-vallée, France 4 Università della Calabria, Italy The study takes place in the northern part of Calabria, Italy, where a potentally actve and capable fault is mapped across the Farneto del Principe’s dam, on the Esaro river. A complex set of geological, geophysical and seismological studies performed jointly by the University of Chiet- Pescara (INGEO) and the Isttuto Nazionale di Oceanografa e di Geofsica Sperimentale (OGS) are ongoing to estmate the fault seismic actvity and its potental surface displacement during major earthquakes. Our study area lies on the Calabrian Arc that represents the emerging part of the Calabrian accretonary wedge. This region is one of the most seismic-actve regions in Italy, with some earthquakes with M ≈ 7.0 (e.g. Feb 1783, Jacques et al., 2001 ). The Esaro valley is located in the Crat Basin in which we fnd several west-dipping faults with a N-S strike like the Roggiano Fault and the Firmo Fault. As it is reported in the ITHACA database, the Firmo Fault is 16.2 km long, and its surface expression might be crossing the Farneto del Principe’s dam but its positon, behaviour and actvity are debated in the literature. To fll this lack of informaton and provide more details about the fault, a multdisciplinary study started in 2022, funded by the Consorzio di Bonifca integrale dei Bacini Setentrionali del Cosentno . The historical seismicity around the dam, analysed by mainly 2 historical databases (CPTI15 and ASMI) shows that the 20 km area around the dam seems to be afected only by superfcial and moderate earthquakes (M < 5.5); a stronger but more distant earthquake occurred in 1184 earthquake, in the Crat valley, M≈7. Concerning the instrumental seismicity, we collected and compared data from 2 diferent catalogues: INGV catalogue (1985-2023, 5 events with M > 3.5) and the University of Calabria catalogue (May 2013-Dec 2023, 0 event with M > 3.5). In these 2 datasets, we can notce that events are less frequent in the closest area around the dam; conversely, there is a concentraton of shallow events (~10 km deep) in the North (Pollino area) and in the South-East. Furthermore, we fnd deeper events (> 30 km deep) that are related to the subducton zone, on the west.