Slip-rates and time recurrences of the seismogenic Sant’Eufemia normal fault (SE Tyrrhenian Sea), a multiscale and multidisciplinary approach

Abstract

Time recurrences and slip rates of paleoearthquakes along offshore seismogenic faults represent one of the key challenges that the scientific community is facing off. Here we provide an integrated study combining geophysical, sedimentological and geochemical data in order to define slip rates and time recurrences of the Sant’Eufemia normal Fault (SE Tyrrhenian Sea). We have documented the paleo-events associated to this geological structure and reconstructed the paleoenvironmental history. From post-LGM (ca. 20,484 yr BP) to Present, four main events (EQ1, EQ2, EQ3, and EQ4) and the historical 1905 Calabria earthquake have been recognized. Time recurrence ranges from 4.68 ± 0.94 to 7.322 ± 1.84 ky (mean value of 5.4 ky), while the co-seismic vertical displacement ranges from 0.21 to 1.085 m (mean value of 0.68 m), indicating that slip rates change along the fault plane moving from the central part to the lateral edges. In this work we have defined a new class of active fault, here named “ultra-slow”, that allowed to extend the range of time recurrences previously provided for the main earthquakes affecting the Southern Apennines. Phenomena that may be related with the oceanic slab sinking beneath the Calabrian arc.