Imaging of the Hellenic subduction zone by seismic tomography

Abstract

The Hellenic subduction zone is a complicated tectonic boundary, along which transitions in the nature of subducted material are believed to occur. The objective of this study was to better constrain the subsurface geometry of the Hellenic subduction zone by increasing the resolution of an existing tomographic model of the region. Increase in resolution is important for understanding the effects of inferred transitions in subducted material at depth. Nonlinear inversion of P-wave travel times was used on a global dataset expanded by temporary array data collected in southern Greece. Results show a vertically continuous slab, with a break at the depth 200-400 km detected only in the NW portion of the system. At depth above 400 kin, there is a lateral discontinuity marked by the Central Hellenic Shear Zone and Kephalonia Transform Fault, with slab more pronounced in southern part of the system. Our study supports the hypothesis of the change in subduction mode between northern and southern part of Hellenic arc in late Pliocene.