GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 ΔCSC = Δτs + μΔσn where ΔCST is the change in Coulomb stress (Coulomb Stress Change – CSC), Δτs is the variaton of shear stress, μ is the fricton coefcient and Δσn is the variaton of normal stress. The fault parameters entered into the sofware are: • strike N160°; dip 70°; rake -90°; kinematc dip-slip; Mw 6.6; maximum slip -2 m for MVFS and -2.5 for NFS (INGV, 2016); fricton coefcient μ=0.6 (typical of carbonate rocks). Two simulatons were conducted, one actvatng the MVFS fault (S1), the other that of the NFS (S2) (Fig. 2). Fig. 2 – Simulaton results for the calculaton of the CST with the Coulomb 3.3 sofware. (S1) Cross-secton with the actvaton of the MVFS. (S2) Cross-secton with the actvaton of the NFS. (S3) Cross-secton with the actvaton of the GSFS. (S4) Cross-secton with the actvaton of the UAFS, with comparison of 2009 seismic sequence. Coulomb stress increase countering (red), Coulomb stress decrease countering (blue). Similarly, two simulatons were conducted for the GSFS (S3) and for the UAFS (S4), with parameters entered the sofware are: • strike N160°; dip 70°; rake -90°; kinematc dip-slip; Mw 6.6; maximum slip -2.5 for both fault systems; fricton coefcient μ=0.6 (Fig. 2). Discussions and conclusions . The combinaton of all these analyses allowed us to hypothesize why the NFS was actvated on the surface and how it interacts with the MVFS. The results obtained from the simulatons for the calculaton of the variaton of the statc Coulomb stress show that, in simulaton S1, the formaton of a stress growth lobe is observed in the frst 2 km in the hanging- wall of the MVFS, corresponding to the superfcial part of the NFS (Fig. 2). In simulaton S2, however, a Coulomb stress increase lobe is observed at ~6.5 km depth in the footwall of the NFS,