GNGTS 2018 - 37° Convegno Nazionale

86 GNGTS 2018 S essione 1.1 Fig. 1 - a) Eastern Sicily: main geodynamic sectors, principal stress axes and principal regional faults proposed as seismogenic master faults of the 1693 earthquakes (DISS Working Group 2018). MEFS = Malta Escarpment Fault System, SRFS = Scicli Ragusa Fault System, AF =Avola Fault, PAFS= Pedagaggi Agnone Fault System; MLF = Monte Lauro Fault, SBT = Sicilian Basal Thrust, STEP = Slab Transfer Edge Propagator fault system. Dashed square shows location of Fig. 1b; b) Southeastern Sicily DEM. Squares are the epicenters of the strongest historical earthquakes (from Rovida et al. , 2016). Stars are the epicenters of revised 1693 seismic sequence shocks. Yellow and red rectangle are the source models of the 1693 earthquake proposed by Barbano and Pirrotta (this volume). Focal mechanism (balloon) refers to the 1990 earthquake (fromAmato et al. , 1995); red dashed square is the location of Fig. 2. We carried out geological, geomorphological and morphometric analyses in the area where maximum damage and environmental phenomena occurred during the 1693 seismic sequence, with the aim to recognize recent activity of faults and to associate them a seismotectonic potential. First, we performed DEM and aerial photos analyses and geological-structural surveys to map faults in detail and to constrain their geometry and kinematics. In addition, we carried out geomorphologic and morphometric studies of four rivers flowing in the area (Cantera, Mulinello, Marcellino and Anapo rivers) with the aim to define the activity of the intercepting faults. Finally, we analysed instrumental seismicity, recorded during 1994-2013 by local network to relate observed faults with the seismicity of south-eastern Sicily. Geological-structural analysis reveals that the study area is dissected by numerous faults, NE-SW and NW-SE oriented, many of them known in literature. Morphostructural and tectonic-geomorphology investigations indicate a general high degree of tectonic activity of the study area and recent activity of some previously mapped faults. We grouped active faults in two systems: the Palazzolo Villasmundo Fault System (PVFS) and the Augusta Floridia Fault System (AFFS) (Fig. 2). AFFS consists of normal faults directed from NW-SE up to NNW-SSE that create several horsts and grabens and correspond to faults already mapped in literature. PVFS dips to west, it