Lithospheric Tomography Structure Beneath Arabia using Surface Waves Group Velocities

Abstract

The group velocity distribution beneath the Arabian Plate is investigated using Love and Rayleigh waves. A balanced path cov- erage was obtained using seismograms generated by earthquakes lo- cated along the plate boundaries in the Red Sea, Gulf of Aqaba, Gulf of Aden, western Iran, Turkey, and the Dead Sea fault system. Tom- ographic inversions of Love- and Rayleigh-wave group velocities have been used to estimate the lateral group-velocity variations in the period range of 5 - 60 s. The Love- and Rayleigh-wave results are consistent and show that the average group velocity increases from 2.38-2.44 km/s at 5-7 s to 3.74-3.98 at 56-60 s, for Rayleigh and Love waves respectively. The tomographic results delineate first-order re- gional structure heterogeneity as well as a sharp transition between the two major tectonic provinces in the region, the Arabian Shield (faster than average) and the Arabian Platform (slower than average). The boundary between the fast and slow regions is sharp and co- incides well with the boundaries of the Arabian Shield for shorter pe- riods, while for longer periods, the fast regions correlate well with the boundaries of the Red Sea.