Seismic deformation pattern in the Friuli-Venezia Giulia region (north-eastern Italy) and western Slovenia

Ten deforming belts of relatively homogeneous deformation have been recognized in the Friuli-Venezia Giulia region (north-eastern Italy) and in western Slovenia, by comparing tectonic and seismological characteristics. The seismic deformation rates of each belt have been calculated from moment tensor summation for the period 1984-2006. The results indicate that the deformation pattern is heterogeneous with a significant strain partitioning among the deforming belts. The belts located in the western part of the study area are undergoing a compressional strain that is changing orientation from a NW-SE to a NNW-SSE direction. The prevailing mode of deformation of the northern and eastern belts in this part of the study area is related to a dextral strike-slip motion, along directions switching from NNE-SSW to NWSE. The deformation geometry of the belts located in the central part of the study area is mainly compressional, N-S oriented. The rates of deformation of the belts related to the dominant mode of deformation vary from 4.8 x 10-5 mm/year to 0.24 mm/year.