LAUSR

Abstract We examine the active stress field of the Southern Aegean Sea subduction area from fault plane solution data, focusing on the variability resulting from the application of different stress inversion methods. The study area is characterized by a high seismicity level and has been struck repeatedly by large destructive shallow and intermediate-depth earthquakes (up to M∼8.0). A larger number of previously published Fault Plane Solutions (FPS), as well as additional FPS computed in the framework of this study, provide the basis for the detailed study of the Southern Aegean active stress field. The active stress field is examined using three well-established algorithms, as well as an adapted method proposed in this study, based on the statistical processing of solutions provided by the Gephart and Forsyth (1984) method. The results obtained from all methods show a systematic consistency, with the Gephart and Forsyth method exhibiting the largest discrepancy, in comparison to other approaches. The determined active stress field reveals several domains with similar seismotectonic characteristics. Along the Southern Aegean (Hellenic) volcanic arc, the roughly North-South extension field shows an excellent correlation with the local arc geometry (arc-normal extension). The outer arc is characterized by compression, as a result of the active subduction, with an almost constant NE-SW direction. Between these two regions, a narrow zone with approximately East-West extension develops along the whole Hellenic Arc with subtle spatial differences, while in the eastern Hellenic Arc a well-developed strike-slip faulting pattern is recognized along the broader area of the Pliny and Strabo trenches. Finally, all intermediate-depth events show the same transpressional pattern, with a characteristic down-dip extension along the subduction direction and an arc-parallel compression, which follows the local arc orientation.