The building of the Apennine belt slowed down or ceased around the Early Pleistocene. Since then, the belt has undergone strong uplift and considerable distortion. Such drastic change, from beltnormal to belt-parallel shortening, has been determined by the fact that the continental Adriatic domain (Adria) was almost completely surrounded by buoyant orogenic structures. In that context, the mobility of Adria underwent a considerable reduction, while uplift and deformation of its southern part was strongly emphasized as an effect of the convergence of the confining plates. Around the middle Pleistocene, the deformation pattern in the periAdriatic zones changed again, in response to the acceleration of Adria. In the Apennines, the outer (Adriatic) sector of the chain underwent belt parallel shortening, accommodated by uplift and outward escape of upper crustal wedges. The separation between the extruding wedges and the almost stable inner belt has generated a series of extensional /transtensional fault systems along the axial part of the Apennines, that now correspond to the main seismogenetic sources. The main tectonic reorganizations in the study area are supposed to have been controlled by the least-action principle.The Apennine chain (Fig. 1) built up during the Miocene and Pliocene as an effect of the subduction of the Adriatic domain beneath the migrating advancing Alpine belt (e.g.