Regional Deformation and Offshore Crustal Local Faulting as Combined Processes to Explain Uplift Through Time Constrained by Investigating Differentially Uplifted Late Quaternary Paleoshorelines: The Foreland Hyblean Plateau, SE Sicily

摘要

Quaternary uplift is well documented in SE Sicily, a region prone to damaging seismic events, such as the 1693 "Val di Noto" earthquake (Mw 7.4), the largest seismic event reported within the Italian Earthquake Catalogue, whose seismogenic source is still debated and, consequently, the long-term seismic hazard is poorly understood. However, the spatial variation in the timing and rates of uplift are still debated, so it is difficult to link the dominant tectonic process(es) responsible for the uplift and the location of seismogenic sources. To better constrain the uplift rate, we have refined the dating of Late Quaternary marine terraces, using a synchronous correlation approach, driven by both published and newly obtained numerical age controls (U-234/Th-230 dating on corals). This has allowed recalculation of uplift rates along a N-S oriented transect within the Hyblean Plateau (HP) foreland region. Consequently, we have mapped the geometry of paleoshorelines along a coastline-parallel transect and hence the rates of uplift. The results suggest increasing uplift rate from south to north across the HP and that uplift rates have remained constant through the Late Quaternary. This spatially changing but temporally constant uplift places constraints on the proportion of uplift produced by regional geodynamic processes versus produced by local faults, such as an offshore east dipping active normal fault. We discuss these new findings in terms of the long-term seismic hazard for one of the most seismically active regions in the Mediterranean Basin.