We compute models for lithospheric P andS velocity structure beneath the South Caspian Basin (SCB) shoreline, to the north of Central Iran block assemblage. The models were derived from regional and teleseismic travel times of compressional and shear seismic phases recorded by a dense temporary array of 24 seismic stations. The models have good resolution in the crust due to small interstation spacing (~14km) and Pn constraints employed in the inversion. Two shallow low-velocity anomalies are resolved as evidence of thick sedimentary depocenters in the SCB and in the northern edge of Central Iran. Two lateral velocity contrasts in the crust and the upper mantle are observed beneath the Gilan plain and the northern flank of the western Alborz range which we interpret as the boundary between the lithospheric structure of the SCB, and that of Central Iran. The results do not favor underthrusting of the SCB beneath Central Iran”.