Structure of the Hellenic Subduction Zone from Gravity Gradient Functions and Seismology

The Normalized Full Gradient (NFG) method has widespread applications in the analysis of potential fields, especially the gravity and magnetic fields. This method is used to identify the lateral and horizontal density variations in the crust and lithosphere. In this study, the NFG method was applied to the gravity data of the Cretan Arc and its surroundings. Because of the tectonic features of the eastern Mediterranean, the Cretan Arc and the neighboring areas are seismically very active. Especially the subduction zone and the complicated crustal features have been defined applying many different geophysical methods. In this study, first the NFG method is tested with synthetic prisms (two cubes). After that, the NFG method was applied to the Bouguer gravity data of the Cretan Arc and its subduction zone (Hellenic subduction zone) and Hellenic subduction zone was defined with the foci depth data (USGS) along the south–north direction. Thus, geometry of the focal depth distribution has been created to determine probable media depths and their localizations. According to the NFG results, vertical structural transitions were observed at a depth ranging between 10 and 180?km. Also, these results were compared with the foci depth model and the other results of the related publications. Finally, some considerations in vertical solution with the NFG method have been presented and locations of the different structures at horizontally have been defined with application of the NFG method.