Crustal and upper mantle structure of the Kozani-Grevena area obtained by non-linear inversion of P and S travel times

The present study focuses on the P and S crustal and uppermost mantle velocity structure in the broader Kozani-Grevena area. The velocity structure is derived from the inversion of travel times of local events. The main data source is the travel times from the aftershock sequence of the large event of 13 of May 1995 (M_w = 6.6) which occurred in the study area. An appropriate preconditioning of the final linearized system is used to reduce ray density effects on the results. An attempt is made to interpret the features and details of the crustal structure in terms of the geotectonic setting of the area. The observed features of the deeper crustal and uppermost mantle structure are in very good agreement with previous results. Specifically, a crustal thickening is observed along a ENE-WSW direction, perpendicular to the well-known Dinaric trend (NNW-SSE) of the geological formations of the area, in accordance with the theoretical expectation of a thicker crust under the accretion prism which starts at the SW edge of the study area.