GNGTS 2019 - Atti del 38° Convegno Nazionale

GNGTS 2019 S essione 1.2 159 data and surface geological data was carried out at regional scale. We sought for possible correlations between the potentially active regional tectonic structures and the distribution of hypocenters of earthquakes recorded in the area during the last 35 years. Studies of historical and recent seismicity, and analysis of geological structures have allowed us to define the main shear strips on a regional scale (Figs. 2 and 3). The active tectonic structures strongly control the late-quaternary geodynamic evolution of the Calabrian Block influencing the current morphotectonic structure (Ghisetti, 1979; Monaco and Tortorici 2000) and producing seismic activity. The Tyrrhenian sector of Southern Calabria is affected by the coeval processes of opening up of the Mesima-Gioia Tauro Valley and the Strait of Messina, in connection with the deformation processes induced by a deep cut area (Monaco and Tortorici, 2000). The NNE-SSO fault system, associated with this opening process of the Pleistocene basins, is a morphotectonic element characterized by high-angle faults which mainly plunging towards the Tyrrhenian Sea, with mainly direct kinematics (Galli and Bosi, 2002). Another active fault system is WNW-ESE striking, currently characterized by normal kinematics, but which have been active in the past mostly as strikeslip faults that accompanied the neogenic evolution of the entire area (Tripodi et al. , 2013, 2018). From the instrumental recording of earthquakes, the resulting picture shows a significant amount of crustal earthquakes of small magnitude, located both on land and at sea (Fig. 3). The epicenters are distributed in a very heterogeneous way and show numerous clusters in areas already affected in the past by strong earthquakes, such as the Mesima valley, the Serre area and the western slope of Aspromonte. Alignments are also evident along well-known seismogenic structures such as the Cittanova fault, Nicotera-Gioiosa Ionica, and Bovalino-Bagnara faults. Furthermore, clusters and alignments of epicenters are observed also in the seas surrounding Calabria. Several seismic sequences with main shock of magnitude mL <4.0 have been recorded during the last decades. These shear zones are, as previously described, grouped according to their orientation essentially in two families, the Fig. 3 - Relationship between registered earthquake epicenters (1986-2017) and recent tectonic structures.