Abstract : To determine the crustal and upper mantle structure between Iran and Turkey, Rayleigh wave portions of the vertical component SRO-ANTO (Seismic Research Observatories- ANkara Turkey Observatory) records of eight earthquakes from Iran and one from eastern Turkey were analysed. One Station Method was used to calculate Rayleigh wave phase velocities in the period range of 12 to 48 seconds.

Theoretical phase velocities for different earth models were computed and comparisons of the calculated and theoretical phase velocities were made. Perturbations of the model parameters were carried out until the best fit was obtained. Six acceptable models with 4 crustal layers (the first 2 may be sedimentary) were found. The average crustal thickness has been estimated to be between 52 and 56 km along the path from eastern Iran to ANTO, between 45 and 48 km along the path from western Iran to ANTO and between 42 and 44 km along the path from eastern Turkey and northwestern Iran to ANTO. The total thickness of the crust decreases by 14 km from Iran to ANTO in east-west direction.

Key Words: Crustal Structure, Rayleigh Waves, Dispersion.