Rapid transient uplift driven by active slab tear, southern Calabria, Italy

Southern Italy preserves a well-studied record of deformation and uplift related to migrating oblique collision, trench retreat, and tearing of subducted ocean slabs. However, the surface expression of these processes is incompletely understood due to a lack of reliable ages for marine terraces >200 m above sea level (masl). Here we use luminescence methods to date shallow marine sands from terraces ~ 100 to 1,000 masl in southern Calabria and interpolate the results with regional surface mapping. Burial ages overlap across the full range of sampled elevations with a weighted mean of 118.8 ± 8.7 thousand years before present (ka). These ages, combined with map data and fault-zone morphology, indicate that the terraces are erosional remnants of a single, once-continuous deformed surface. Calculated uplift rates vary from <1 to >12 mm yr-1 and throw rates on active normal faults are 0.8–4.2 mm yr-1. We infer that rapid post-120 ka uplift is an ongoing isostatic response to an active tear in the Ionian slab, consistent with recent geophysical observations and predictions of geodynamic models. These results have important implications for assessment of geohazards in southern Calabria and northeast Sicily, one of the highest seismic risk areas in the Mediterranean region.