Seismic Cycle of the Southern Apennine Deformation Front: The Taranto Gulf Marine Terraces Inputs and Implications

Detailed tectonic analyses and geological mapping in muddy fold-belt front is a hard target. Using both fieldwork and GIS software associated to new soil datations (Sauer et al. in Soil development on marine terraces near Metaponto. Gulf of Taranto, Southern Italy, pp. 1-16, 2009) of the different marine terraces of the Taranto Gulf (Southern Italy), we were able to precise the location of the Metaponto-Pisticci staircase which appear to be situated above the first thrusting unit of the southern Apennine orogen corresponding to the deformation front. Consequently we can locate, characterize and quantify from an active tectonic point of view the deformation front of southern Apenines. By combining our data with (1) the AGIP seismic profile offshore the Taranto gulf that gives the precise geometry of the overthrusting sheet, (2) the known eustatic curve of the mediterranean sea along the southern Italian shore, and (3) the soil datations of the different terracic levels, we are now able to differentiate the signal of both active tectonic and eustatic processes and their related geomorphic features on the Taranto Gulf marine terraces. Therefore the observed seismic cycle of the Southern Apennine deformation front is revealed and characterized by a return period of about 261 ka, a vertical uplift of about 113 m and a shortening rate of 2.1 km by return period. Its deformation is not uniform and appear to be coherent with both a regular interseismic linear creep period (time = 251 ka/uplift = 71 m) and a rapid inferred cosismic uplift (time: lOKa/uplift = 42 m) that we interpret as a sismogenic period with probably numerous major earthquakes. Finally thanks to the marine terraces of the Metaponto-Pisticci staircase that lead us to better understand the deformation front of Southern Apenine and its associated landscape and to separate erosion and tectonic processes.