GNGTS 2022 - Atti del 40° Convegno Nazionale

GNGTS 2022 Sessione 1.1 61 Mildon et al. (2016), Coulomb stress transfer is highly sensitive to strike-variable geometries of the receiver faults. Since a realistic CAFS base model is of paramount importance in reducing calculation errors, we adopted a new strike-variable and ellipse-shaped three-dimensional model as input file for the Coulomb stress transfer simulations. To do so, we used “3-D Faults” (Mildon et al. , 2016) and “Coulomb 3.4” (Lin and Stein, 2004; Toda et al. , 2005) MATLAB codes. To test the efficiency and the effective influence of this new model in terms of coulomb stress transfer results, we performed calculations on both planar-rectangular faults and strike- variable and elliptic faults. We used the same receiver and source faults but two different geometric model to find and quantify differences. We performed coulomb stress transfer simulations on each seismic event within each seismic sequence taking into account to respect the real rupture conditions (e.g., partial or entire rupture, slip distribution) of the earthquake. Results confirmed that the cumulative seismic energy released during the last 1000 years was similar in the 3 main time-windows separated by ca. 350 years of time gap as hypothesized by Tondi and Cello (2003). Furthermore, the results obtained in the CAFS central area validate the thesis proposed by Galderisi and Galli (2020) regarding themutual and alternating Coulomb stress transfer between Norcia Fault and Monte Vettore Fault. Fig. 1 - Map of the 18 seismic events with 5.8 ≤ Mw ≥ 7.0 in the CAFS area since 1279A.D. labelled according to the chronological order within each time-window of seismicity. Main active fault traces are also shown (CFFn – Colfiorito Fault nord; CFFs - Colfiorito Fault south; MVF – Monte Vettore Fault; NF – Norcia Fault; CF – Cascia Fault; LF – Laga Fault; GSF – Gran Sasso Fault; PZF – Pizzoli Fault; PF – Paganica Fault; PTF – Pettino Fault; CTF – Cerasitto Fault; CFLF – Campo Felice Fault) (Tondi, 2000; Galderisi and Galli, 2020; Tondi et al. , 2020; Galli et al. , 2022 and references therein).