Crustal velocity and Moho structure beneath the Gulf of Corinth, Greece

Abstract

The Gulf of Corinth (GOC), Greece is a continental rift with high rates of seismicity and extensional strain. How this strain is accommodated in the crust and whether there are variations in the mechanism along strike remain open questions, in part because of a lack of wide-angle reflection/refraction studies that constrain crustal velocity structure. In 2001, an extensive multichannel seismic survey was conducted within the GOC, one component of which included the wide-angle recording of sources from within the gulf at stations on land surrounding the gulf. In this paper we use wide-angle data in two separate, but allied, studies to constrain crustal velocities and depth to the Moho. A 2-D inversion of refraction and reflection traveltimes along an axial profile through the GOC constrains the shallow crustal velocity structure, images the Moho at 29 km depth in the east, dipping to 39 km in the west, and images the eastward subducting African slab beneath the western GOC at a depth of 74 km. The 1-D average of the 2-D velocity model was used in a tomographic inversion of PmP reflection times to solve for depth to the Moho throughout the Corinth region. This model shows generally thick, isostatically compensated crust (≥37 km) beneath the Hellenide Mountains, except immediately south of the GOC, and a singular region of thin crust (<30 km) beneath the Perahora Peninsula at the eastern end of the gulf. A comparison with Moho depths derived from gravity inversion shows a general agreement with crust thickening from east to west, but a number of differences in detail. The 3-D crustal thickness variations are more complex than those predicted by either pure shear or simple shear models of continental extension and suggest significant pre-rift structural variability.