GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.1 GNGTS 2024 Investgatng the Infuence of Coulomb Stress Transfer in the Actvity of the Central Apennine Fault System (CAFS) Over the Last Millennium G. Valentni 1,2. , T. Volatli 1 , P. Galli 3,4 , E. Tondi 1,2 1. School of Science and Technology - Geology Division, University of Camerino, Italy. 2. Natonal Insttute of Geophysics and Volcanology, Rome, Italy 3. Dipartmento Protezione Civile, Rome, Italy 4. Consiglio Nazionale delle Ricerche, Isttuto di Geologia Ambientale e Geoingegneria, Rome, Italy The actve Central Apennine Fault System (CAFS) witnessed several destructve seismic events over the last millennia. Although numerous investgatons have highlighted the role of Coulomb Stress Transfer (CST) in the onset of some of the most devastatng earthquakes globally, there is limited scientfc documentaton pertaining to its specifc impact within the CAFS. This research delves into and thoroughly examines the efects of CST on both historical and instrumental seismic events of signifcant magnitude associated with the CAFS. 15 seismic events within the CAFS region datng from 1279 to present with magnitudes higher than Mw 6.0 were selected. Specifcally, 9 were selected for the CST investgaton, based on their proximity to subsequently actvated faults both spatally and temporally. Beyond analyzing the statc stress transfer for each individual seismic event, the cumulatve CST of recent instrumental earthquakes was also examined to provide a comprehensive overview of the current stress scenario. Leveraging an innovatve approach, faults were modeled in three dimensions, adoptng an ellipse as the most accurate representaton of their 2D geometry. Considering the CST's sensitvity to strike variatons, a variable strike three-dimensional elliptcal model was therefore implemented, ensuring enhanced calculaton accuracy. Valentni et al. (2023) identfy three prominent periods where most of the seismic moment was released. The inital phase spans from ~1300 CE to ~1400 CE, followed by a surge around 1700 CE, and the most recent phase extends from 1979 to 2016 with 300-350 years intervals. However, the scale of the released seismic moment varies across these distnct seismic periods. The frst seismicity window cumulatve seismic moment is approximately 1.35 tmes greater than the second phase and about 2.31 tmes that of the third phase. With the current data in consideraton, it seems plausible to hypothesize the existence of a notable seismic gap in the ongoing historical period. Should this gap exist, it implies the need for a seismic event substantal enough to bridge this gap. Herein we will examine the factors that may infuence this seismic gap and identfy which