VHR seismic imaging of displacement along an active off-shore fault system of the Adriatic foreland

Abstract

A dense network of Very High Resolution seismic profiles along the Gondola Fault Zone (GFZ), in the Adriatic foreland (Italy), reveals the geometry and Middle Pleistocene-Holocene activity of this inherited, E-W, strike-slip fault system. The GFZ is >50 km long and includes two parallel fault sets, characterized by subvertical planes displaying a vertical component of motion, associated with two main anticlines. The northern fault set is organized in three branches, whereas the southern one includes two branches. The overall geometry of the GFZ suggests dextral slip. The distribution of the vertical displacement is bell-shaped, suggesting a long-term behavior as a single structure. However, individual branches show different deformation histories, implying that they can slip independently. The vertical slip rates, calculated for late Middle Pleistocene to Holocene intervals, are consistently small within a limited range (0-0.19 mm/a).