GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.1 - POSTER GNGTS 2023 favorable cases it also allows to obtain the direction and inclination of the fault plane through the hypocenters interpolation. The study of the distribution of the hypocenters and the estimation of the volume has been carried out with Matlab. Figure 2. a) Seismic stations used for the analysis of the Mesima valley and Bagnara Calabra swarm, RL indicates the stations used for relative location. b) 3D representation of the hypocenters obtained from relative location and their fit with a plane. c) Computation of the seismogenetic volume based on the distribution of hypocenters. ​ Results This paper describes the results of the analyses performed for two swarms: the Mesima valley swarm (2019) and the Bagnara Calabra swarm (offshore, 2018). The Mesima valley swarm occurred from April to May, with a main event of magnitude 3.6 which happened on May 26, 2019 at 23:31 UTC (lat. 38.492°, lon 16.145°, depth 19.45 km), followed by more than a hundred of lower magnitude events. Subsequently, many other events likely related to the same seismogenetic structure occurred sparsely over the following months and also in 2020. The starting dataset consists of about 300 earthquakes, selected in a circular area with radius 10 km around the mainshock epicenter. These events were located with high accuracy using all available data, and 172 of them have epicenters within an area of 2x2 km 2 (Fig. 1a) and depths between 17 and 20 km. Most of these earthquakes were located with an azimuthal gap of about 100 degrees due to the good distribution of seismic stations around the epicenter area (Fig. 2a). To assess the quality of the picking, the modified Wadati diagram (Chatelain, 1978) has been computed, from which a