Stress and strain patterns in the Venetian Prealps (north-eastern Italy) based on focal-mechanism solutions

Stress and strain patterns are inferred from fault-plane solutions in the seismotectonic domains of the Venetian Prealps, north-eastern Italy. This area represents a peculiar geodynamic sector of the eastern Southalpine Chain, where seismicity marks the indentation between the Adria microplate and the Eurasian plate within a complex tectonic setting. Three distinct seismic districts are investigated (Lessini – L; Pedemontana North and South – PN with PS; and Alpago-Cansiglio - A). Inferences on the stress and strain tensors are based on 55 fault-plane solutions of seismic events that occurred between 1987 and 2014 (magnitude range: 2.6-4.7). Results show that the collision between Adria and the Eurasian plate is generally accommodated by a strike-slip regime. All zones are mainly characterized by focal mechanisms of strike-slip and thrust type, with a wide range of nodal plane orientations, reflecting high crustal structure heterogeneity and a complex pattern of failure planes. The comparison between the principal axes of stress and strain suggests that the L zone is also characterized by a high mechanical strength heterogeneity, which is less pronounced in PN with PS and A zones.