The Ligurian sea: new seismotectonic evidence

he current and historical seismicity of the Ligurian Sea and surrounding regions has been analyzed in order to obtain closer seismotectonic correlations. The seismicity and focal mechanisms indicate particular differences between the different sectors of the Ligurian Basin. The seismicity of the eastern side of the Basin, corresponds to an active band in the western side, where there is transpression along both the margin foot and the basin axis. The margin, as evidenced by a seismic reflection survey, appears to be segmented by a fault system consisting of a net of transversal faults intersecting step faults parallel to the coast. At the foot of the margin, sedimentary basins displaced en echelon are cut throughout their thickness by active normal faults, and the seismic activity concentrates at the intersections of main faults. To explain apparently contrasting results, a simple couple of forces acting in opposite directions in the Ligurian Sea and in the Po Valley has been hypothesized.