Deep structure of the crust in the area of the 2016-2017 Central Italy seismic sequence from receiver function analysis

We compute a high-resolution topographic model of the Moho beneath the fault system activated during the 2016-2017 Central Italy seismic sequence, using Receiver Function (RF) analyses. We document that Ps conversions recorded in RF data-set varies abruptly at very short distance across the crustal lineament called Ancona-Anzio Line (AAL). Moho depth varies from about 25-30 km in the Tyrrhenian domain on the West to 35-40 km in the Adriatic domain in the East. Where the two domains are juxtaposed along the AAL, Moho depth values cluster around 50 km depth, in a stripe-like area 20 km wide. Such unique feature marks the deformation zone in the lithosphere and testifies the abrupt change in delamination style in the two sectors of the Apennines. Intermittent large normal faulting earthquakes driven by across-belt extension break through such inherited strong structural changes, conditioned by localized barriers to fluids migration and overpressuring.