GNGTS 2019 - Atti del 38° Convegno Nazionale

10 GNGTS 2019 S essione 1.1 SEISMICITY INDUCED BY THE DYNAMICS OF THE SOUTHERN FLANK OF MT. ETNA (SICILY, ITALY): THE TRECASTAGNI FAULT ACTIVITY IN FEBRUARY 2019 S. Alparone 1 , S. Gambino 1 , S. Grassi 2 , S. Imposa 2 , G. Patti 2 , A. Ursino 1 1 Istituto Nazionale di Geofisica e Vulcanologia - Osservatorio Etneo - Sezione di Catania - Catania 2 Università degli Studi di Catania - Dipartimento di Scienze Biologiche, Geologiche e Ambientali - Sezione di Scienze della Terra - Catania Introduction. Mt. Etna is one of the most active volcanoes in the world and is considered one of the most interesting natural laboratories for the understanding of eruptive processes and the ascent of magma. The geodynamic framework of Mt. Etna is located within the collisional process of the Eurasia and Africa plates with a roughly N-S trend and E-W extensional regime. The volcano edifice is located at the intersection of the two major regional structural lineaments, with NNW-SSE and NE-SW trends, which play a fundamental role in the dynamic processes of the volcano (Bonaccorso et al. , 1996, Gresta et al. , 1998). The complex interaction between regional stress, gravity force and dyke-induced rifting, has caused the slow sliding of the eastern and south-eastern flanks of the volcano (Borgia et al. , 1992; Lo Giudice and Rasà, 1992; Monaco et al. , 1997; Borgia et al. , 2000; Neri et al. , 2004; Walter et al. , 2005). Therefore, the dynamics of the eastern flank seems to have a key role in the triggering of volcanic eruptions. The eastern flank dynamics is controlled by several fault systems; among these, the Provenzana-Pernicana fault represents the northern boundary. The earthquakes occurring along this structure mainly take place in the form of seismic swarms, even of low energy. The main events reach magnitudes of up to 4.3 and sometimes cause damage to existing structures (Alparone et al. , 2013 and references therein). From west to east, the Ragalna, Tremestieri Etneo and Trecastagni faults (Azzaro, 1999), which in some places have evident morphological slopes (Gambino et al. , 2011), make up the southern boundary of the eastern flank. These structural lineaments release energy in the form of aseismic creep and generate earthquakes that are mostly isolated with medium energy. The seismic sources are characterized by extremely superficial foci, which sometimes cause moderate damage to existing structures. Although it has been recognized as a southern boundary, these structural fault systems have not been affected in recent decades by significant seismicity, showing a low rate of occurrence. This characteristic, probably linked to the scarce detection of Finocchio D., Barba S., Basili R.; 2016: Slip rate depth distribution for active faults in Central Italy using numerical models . Tectonophysics 687, 232–244. https://doi.org/10.1016/j.tecto.2016.07.031 MSC Software Corporation; 2018: Marc 2018.1 Volume A: Theory and User Information <http://www.mscsoftware. com/it/product/marc>. Pezzo G., Merryman Boncori J.P., Tolomei C., Salvi S., Atzori S., Antonioli A., Trasatti E., Novali F., Serpelloni E., Candela L., Giuliani R.; 2013: Coseismic Deformation and Source Modeling of the May 2012 Emilia (Northern Italy) Earthquakes. Seismol. Res. Lett. 84, 645–655. https://doi.org/10.1785/0220120171 Scholz C.H.; 2019: The Mechanics of Earthquakes and Faulting . Cambridge University Press. https://doi. org/10.1017/9781316681473 Trasatti E., Kyriakopoulos C. and Chini M.; 2011: Finite element inversion of DInSAR data from the Mw 6.3 L’Aquila earthquake, 2009 (Italy) . Geophys. Res. Lett. 38. https://doi.org/10.1029/2011GL046714 Wang H.; 2000: Theory of linear poroelasticity with applications to geomechanics and hydrogeology . Princeton University Press.