Interseismic and long-term deformation of southeastern Sicily driven by the Ionian slab roll-back

Abstract. New satellite geodetic data challenge our knowledge of the deformation mechanisms driving the active deformations affecting Southeastern Sicily. The PS-InSAR measurements evidence a generalized subsidence and an eastward tilting of the Hyblean Plateau combined with a local relative uplift along its eastern coast. In order to find a mechanical explanation for the present-day strain field, we investigate short and large-scale surface-to-crustal deformation processes. Geological and geophysical data suggest that the southward migration of the Calabrian subduction could be the causative geodynamic process. We evaluate this hypothesis using flexural modeling and show that the overloading of the Calabrian accretionary prism, combined with the downward pull force induced by the Ionian slab roll-back, are capable of flexuring the adjacent Hyblean continental crust, explaining the measured large-scale subsidence and eastward bending of the Hyblean Plateau. To explain the short-scale relative uplift evidenced along the eastern coast, we perform elastic modeling on identified or inferred onshore and offshore normal faults. We also investigate the potential effects of other deformation processes including upwelling mantle flow, volcanic deflation, and hydrologic loading. Our results enable us to propose an original seismic cycle model for Southeastern Sicily, linking the current interseismic strain field and the available long-term deformation data. This model is mainly driven by the southward migration of the Ionian slab roll-back which induces a downward force capable to flexure the Hyblean crust.