Possible occurrence of low-angle normal faults in Central and Northern Greece

During the elaboration of the Greek Database of Seismogenic Sources (Gre.Da.SS) (Pavlides et al., 2010; Sboras et al., 2009) many active faults of Central and Northern Greece were analysed in detail either from literature sources or new field data in order to reassess their principal seismotectonic parameters. Based on the great amount of information gathered for the database and especially on its good uniformity, in different and distinct areas of central and northern Greece it is possible to observe fault systems very similar in terms of geological setting and structural pattern. For these crustal volumes, the collected data suggest the occurrence of parallel synthetic, and sometimes antithetic, faults merging at depth on low-angle fault planes. The fault geometry, kinematics and tectonic evolution of these regions were compared with the well-known (and widely accepted) detachment fault zone characterising the Gulf of Corinth. In continental central-northern Greece, at least three other regions, from which the two have been already more or less explicitly suggested by other authors, are probably associated with low-angle faulting at depth. The occurrence of a low-angle shear zone has important consequences not only for the geodynamic processes and the crustal extension behaviour, but also for seismic hazard assessment (SHA) estimations.