Geo-structural evidence for active oblique extension in south-central Italy

Active tectonic processes in south-central Italy have been analyzed by means of spatial and kinematic analysis of fault zones In (i) the axial zones of the Apenninic mountain chain, where most of the seismic strain is released within intramontane basin areas (i.e., Norcia, Fucino, Vallo di Diane, high Agri Valley, etc.); and (ii) in the Gargano promontory, where earthquakes with magnitudes up to 6 and 7 have Occurred. Our work focuses on a better understanding of the most recent deformation processes acting in these areas, and the relative motion between the Adriatic and Tyrrhenian crustal units. In order to derive the information above, we integrated structural and seismological data from the Apennines and the Gargano area. The results of our analysis show that the style of active deformation in both of these areas is broadly consistent with the current stress field. Kinematic data from slip indicators on active fault planes are, in fact, consistent with the geometric proprieties and spatial arrangement of the various fault segments and indicate that most of the active structures are characterized by oblique motion. The overall direction of extension appears to be at fairly high angle to the trend of the Apennines, with a component of horizontal left-lateral motion between Tyrrhenia and Adria.