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 (Permanent Scatterer Interferometry Synthetic Aperture Radar) measurements evidence a generalized subsidence and an eastward tilting of the Hyblean Plateau, combined with a local relative uplift along its eastern coast. 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 combined downward pull force, induced by the Ionian slab roll-back and the overloading of the Calabrian accretionary prism, is strong enough to flex the adjacent Hyblean continental domain, 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 with 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 of flexuring the Hyblean crust.