GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 1.1 GNGTS 2023 cumulated M w =6.7 in CPTI15), and, tentatively, also for the northernmost shock of the devastating 1857 earthquake sequence (cumulated M w =7.0). We integrate the REE analysis approach with a high-resolution topography analysis along 98 serial topographic profiles to measure vertical separations attributable to post Late Glacial Maximum (LGM) faulting, following the methodology by Bello et al. (2021). The asymmetric scarp height profiles suggest fault lateral propagation and along-strike variations in the fault evolution. This integrated and multidisciplinary approach highlights the occurrence of seven-to-eleven earthquakes with variable slip between ~40 cm and ~70 cm within post-LGM times (Fig. 2). By applying empirical equations from the literature we speculate on the magnitudes of the respective earthquakes obtaining magnitudes to be between 5.5 and 7.0, and most commonly between 6.3 and 6.5. The results suggest a recurrence time between 1.6 and 2.3 ky and a slip rate ranging between 0.6 and 0.9 mm/yr and offer an approach useful in similar worldwide tectonic contexts. Figure 1. Conceptual three-dimensional model (not to scale) that explains the principle behind our study (adapted from (Mouslopoulou et al., 2011)). The soil, rich in REE-Y, enriches the carbonate of the fault plane with which it is in contact until the moment in which it is exhumed due to a seismic event of such magnitude as to be able to break the topographic surface. The mechanism is repeated with each earthquake causing surface faulting. The displacement associated to an earthquake (e.g., EQx in this figure) is given by the distance between the top of an enriched level (e.g., L3 in this figure) and the top of the next enriched level (e.g., L2 in this figure).