GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 Source parameters of the 2010-2014 Pollino (Italy) seismic sequence and their relatonship with structural and geological setng of the area M. Ponte 1 , G. Calderoni 2 , R. Di Giovambatsta 2 , M. La Rocca 1 1 Università della Calabria, Dipartmento di Fisica, Rende, Italy 2 Isttuto Nazionale di Geofsica e Vulcanologia, Rome, Italy Between 2010 and 2014, a seismic swarm of thousands of events (Mwmax= 5.2) occurred in the Mt. Pollino area, between the Calabrian Arc and the Apennines, adjacent to the Ionian Subducton Zone. High resoluton source locaton revealed that seismicity originated from two main clusters with opposite dipping orientatons, with the main faults aligned along a NNW-SSE directon. Understanding the source parameters of these seismic events is crucial to get insight on the individual rupture process of the earthquake, the spatal evoluton of the seismic sequence and the dynamic propertes of the rupture, including the possible involvement of fuids. We analyzed hundreds of earthquakes of the Pollino seismic sequence in order to investgate the following source parameters: the Brune stress drop (Δσ), the apparent stress (τa) and the Savage- Wood radiaton efciency (ηsw= τa/Δσ). We identfed 20 seismic events with 3.1 < Mw < 5.2 with known TDMT soluton and 80 smaller events with 2.4 < M L < 3.0 not present in the TDMT archive. For earthquakes not included in the TDMT archive we calculated the seismic moment through spectral scaling of the low frequency plateau in the displacement spectra using the corresponding target event selected on the basis of the distance, larger-magnitude, and greatest number of statons that recorded the event. The two stress parameters depict a similarly scatered trend, with the highest value corresponding to the main shocks. Seismic efciency is substantally stable versus M0, with values mostly between 0.1 and 0.6, and a mean value of about 0.23, which corresponds to the expectaton of the omega square model. The area afected by the 2010-2014 sequence extends from the Mercure basin to the Campotenese and Morano Calabro basins and it is characterized by a complex system of normal and oblique normal faults (Fig. 1). The area towards the Tyrrhenian side (west) is made up of faults with a NS trend with E/NNE dip and dip-slip kinematcs, alternatng with segments of faults with WNW-ESE orientaton with normal-slip kinematcs whose ant-slip component is important. The intramontane area is characterized by NW-SE faults dipping towards the SW that are included in a "western system" and an "eastern" system.