Drawing a Seismic Source Zone Model Using Cumulative Seismic Moment Release and Moment Tensors in the Italian Peninsula

In the frame of the elaboration of a new seismic hazard model of Italy, the identification of the areas with homogeneous tectonic regime is needed as one of the objective elements for designing the seismic source zones.A collection of all seismic moment tensors available for Italy for earthquakes with magnitude greater than or equal to 4.0 since 1960 was gathered. It contains data from different catalogs or datasets, mainly populated by moment tensors computed through inversion of seismic waves (e.g. CMT, RCMT, GFZ and ETHZ MT and so on). However, for great earthquakes of the past, i.e. the 1962 Irpinia or the 1968 Belice earthquakes (both max Mw > 6.0) we used data obtained with other methods, but always considered the best available information for that time.All these data helped to find the predominant fault mechanism, considered the typical tectonic style for a region or, using regular grids, for all seismic areas of the Italian peninsula and regions around. To identify the most seismic regions, we used data from historical and recent instrumental seismicity (CPTI15, http://emidius.mi.ingv.it/CPTI15-DBMI15/ and INGV bulletins, http://iside.rm.ingv.it/) combined on a regular grid, obtaining seismic moment release maps. Overlapping cumulative moment tensors to seismic moment release maps, we identified regions clearly characterized by different tectonics. In particular, the extension is the principal type of deformation along most of the Apennines, somewhere interrupted by strike-slip mechanism. Compressive deformation appears in the eastern Alps, in the outer part of the northernmost sector of the Apennines, in several parts of the Adriatic Sea and in the off shore of Northern Sicily. We considered this tectonic style mapping to help with drawing seismic area sources for the new seismic hazard model of Italy.