# New Insights on the Seismic Activity of Ostuni (Apulia Region, Southern Italy) Offshore
## 2 Structural Setting  
In the framework of the Adria plate geodynamics, the Southern Adriatic Sea area represents the Oligocene-Quaternary foreland basin of the Dinarides-Albanides-Hellerides orogen's portion [15; 16; 17; 18] (Figure 3). During the orogenic growth of the Dinarides-Albanides-Hellerides, the Mesozoic-Eoocene Adriatic Basin was gradually involved to the west in the foreland basin, whose tectonic subsidence came to affect the southeastern part of the adjacent Apulia Platform as well [18]. To the west, the Apulia Platform progressively subsided, eastward, in the Neogene-Quaternary foredeep domain of the Southern Apennines [19; 20]. Therefore, a remnant of the Apulia Platform dominates the Apulian Foreland, i.e., the Plio-Pleistocene foreland shared by Apennines and Dinarides-Albanides-Hellerides [19; 21] (Figure 3).  
The uplift since the Middle Pleistocene of the Apulian Foreland occurred in relation to a NW-SE striking regional, gentle buckle fold of the Adria plate, which occurred due to the difficult eastward roll-back of the continental lithosphere during Apennines subduction [20].  
In its upper part, the Apulian Foreland is chiefly represented by a sedimentary cover lying above a Variscan crystalline basement [19] (Figure 3). From the bottom to the top, the sedimentary cover consists of Permo-Triassic continental deposits belonging to the Verrucano Fm (up to ca. 1000 m thick), Upper Triassic limestones/dolostones and anhydites of the Burano Fm (up to ca. 2500 m in thickness), and Lower Jurassic limestones of the Calcare Massiccio Fm (up to ca. 1000 m thick); moreover, the Middle Jurassic-Upper Cretaceous inner platform carbonates, belonging to the Apulia Platform, are widely exposed in the Apulian Foreland with a thickness of \(\sim\)4 km [19; 22; 23].  
The Apulia Platform-basin transition and adjacent Adriatic Basin (Figure 3) are testified by marginal and pelagic carbonates (both cropping out and drilled), respectively [24; 25]. Similar deposits, moreover, occupied during Upper Cretaceous narrow intra-platform basins governed by extensional faults [25; 26; 27].  
The central sector of the emerged Apulian Foreland is represented by the Murge (Figure 4), a morpho-structural high where the exposed carbonates of the Apulia Platform have been grouped in the \"Calcare di Bari\" Fm (Lower Cretaceous) and the overlying \"Calcare di Altamura\" Fm (Upper Cretaceous) [22] (Figure 4). Thin Plio-Pleistocene sedimentary bodies made of calcarenites, which in turn belong to the \"Calcarenite di Gravina\" Fm, unconformably rest on the Cretaceous carbonates, and they crop out in some inner places and especially on the flanks of the Murge high [22], the latter controlled by normal faults [29; 30; 31] (Figure 4). Normal faults striking from NW-SE to W-E, toward the Adriatic Sea coastline, and dipping from the NE to N, respectively, characterize the Quaternary tectonics of the Murge area [30; 31], and, together with associate faults dipping in the opposite direction, gave rise to narrow grabens [30]. According to [PERSON] [32], these tectonic structures composed a system of faults (deformation zones, DZs) with normal and right transtensional kinematics that were active during the deposition of the limestones of the \"Calcare di Altamura\" Fm (Figure 4).