GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 Preliminary results of the Non-Double-Couple seismic sources in the Southern Apennines P. Roselli 1 , L. Scognamiglio 2 , F. Di Luccio 1 , M. Palano 3 , G. Ventura 1 1 Isttuto Nazionale di Geofsica e Vulcanologia, Roma 1 (Roma, Italy) 2 Isttuto Nazionale di Geofsica e Vulcanologia, ONT (Roma, Italy) 3 Isttuto Nazionale di Geofsica e Vulcanologia, Osservatorio Etneo (Catania, Italy) The seismic moment tensor analysis is an efcient way to beter understand earthquake source processes as well as fault kinematcs. Although earthquake sources are assumed to be shear ruptures with associated Double-Couple seismic moment tensors (DCMT), it is widely accepted that the faultng mechanism may include fracture opening and closing, rupture on a non-planar surface or multple sub-ruptures that, in turn, produce signifcant Non-Double-Couple components of the moment tensor (Frohlich, 1994). Therefore, the seismic moment tensor can be decomposed into the isotropic (ISO), compensated linear vector dipole (CLVD) and double-couple (DC) components (Knopof and Randall, 1970). The sum of the ISO and the deviatoric parts (DC and CLVD) consttute the full seismic moment tensor (FMT). DC represents the pure shear moton from two orthogonal vector pairs of equal magnitude but opposite sign; the ISO represents the isotropic volumetric change in the crack closures or implosions; the CLVD represents moton away or toward the earthquake sources with no net volume change and generally complex more physical interpretaton (Frohlich, 1994; Julian et al., 1998; Martnez-Garzón et al., 2017). It is known that mixed shear-tensile earthquakes nucleate in geothermal and volcanic zones, where over- pressurized fuids concentrate (Ross et al., 1996; Saraò et al., 2010; Hrubcovà et al., 2021) and in areas of fuid extracton or injecton, where hydraulic fracturing processes easily occur (Zoback, 2007; Ellsworth, 2013; Martnez-Garzón et al., 2017; Dost et al., 2020; Roselli et al., 2023). Here we investgate, the DCMTs and FMTs of the earthquakes from seismic sequences occurred in the Southern Apennine chain (Italy); these include the 2013-2014 Sannio-Matese (Di Luccio et al., 2018) and the 2010-2014 Pollino (Pastori et al. 2021; Napolitano et al., 2021) sequences. Our data- set consists of the waveforms (M L 2.5) recorded by both natonal permanent and local temporary networks operated by the Isttuto Nazionale di Geofsica e Vulcanologia (htp:// www.orfeus-eu.org/data/eida/ ; Passarelli et al., 2012). To properly cover diferent magnitude ranges and to compare the results, we apply diferent approaches and specifcally the Time Domain Moment Tensor (Dreger & Helemberger, 1993; Dreger 2003) and Isola (Sokos & Zahradník, 2018) for M L > 3.2, hybridMT (Andersen, 2001; Kwiatek et al., 2016) for M L ≤ 4. Our primary goal is to understand the role played by fuids to defne type and space-tme variability of the source parameters and the behavior of the DC, ISO and CLVD components during the seismic sequences in the Southern Apennines. ≥