Eastern Mediterranean gravity potential and the Hellenic subduction process

Tornographic images of the Mediterranean upper mantle P-wave velocity structure have been used to analyse the gravity potential in the vicinity of the Hellenic subduction zone. The velocity anomalies are assumed to be proportional to density variations according to Birch's law. The effect of the topography on the geoid in the region is also calculated. The results indicate that the upper mantle geoid signal probably has significant amplitudes of several metres, but it correlates poorly with the observed geoid. The geoid calculated from topography correlates well, but has an amplitude that is too large in comparison with the observed geoid. The results show that an improved understanding of the Hellenic subduction zone geoid requires refinement of the Moho topography, so that the effect of this topography can be separated from the upper mantle signature.