Seismic ambient noise of surface wave tomography was applied to estimate Rayleigh wave empirical Green's functions (EGFs) and then to study crust and uppermost mantle structure beneath the Makran region in southeast Iran. 12 months of continuous data from January 2009 through January 2010, recorded at broadband seismic stations, were analyzed. Group velocities of the fundamental mode Rayleigh wave dispersion curves were obtained from the empirical Green's functions. Multiplefilter analysis was used to plot group velocity variations at periods from 10 to 50 s. Using group velocity dispersion curves, 1-D v S velocity models were calculated between several station pairs. The final results demonstrate significant agreement to known geological and tectonic features. Our tomography maps display low-velocity anomaly with SW-NE trend, comparable with volcanic arc settings of the Makran region which may be attributable to the geometry of Arabian Plate subducting beneath the overriding the Lut block. The northward subducting Arabian Plate is determined by high-velocity anomaly along the Straits of Hormuz. At short periods (\20 s), there is a sharp transition boundary between low-and high-velocity transition zone with the NW trending at the western edge of Makran which is attributable to the Minab fault system.

Abstract. We applied seismic ambient noise surface wave tomography to estimate Rayleigh wave empirical Green's functions from cross-correlations to study crust and uppermost mantle structure beneath the Makran region in south-east Iran. We analysed 12 months of continuous data from January 2009 through January 2010 recorded at broadband seismic stations. We obtained group velocity of the fundamental mode Rayleigh-wave dispersion curves from empirical Green's functions between 10 and 50 s periods by multiple-filter analysis and inverted for Rayleigh wave group velocity maps. The final results demonstrate significant agreement with known geological and tectonic features. Our tomography maps display low-velocity anomaly with south-western north-eastern trend, comparable with volcanic arc settings of the Makran region, which may be attributable to the geometry of Arabian Plate subducting overriding lithosphere of the Lut block. At short periods (<20 s) there is a pattern of low to high velocity anomaly in northern Makran beneath the Sistan Suture Zone. These results are evidence that surface wave tomography based on cross correlations of long time-series of ambient noise yields higher resolution group speed maps in those area with low level of seismicity or those region with few documented large or moderate earthquake, compare to surface wave tomography based on traditional earthquake-based measurements.