Variations of the Crustal Structure of Arabia

Abstract

Data from the broadband seismic stations deployed in Saudi Arabia during 1996 made it possible to study the variation of surface wave dispersion of the Arabian plate as a function of azimuth. Careful selection of the paths from earthquakes associated with the boundaries of the Arabian plate was made, and the group velocities of the fundamental mode of both Love and Rayleigh waves along these paths were studied. Results show that the Arabian plate is characterized mainly by two different sets of similar group velocity curves that are related to the two major geological units, the Arabian shield and the Arabian platform. The group velocities along paths that traverse the eastern, northeastern, and northwestern regions of Arabia are found to be representative of the Arabian platform geologic province, and are slower than those along the Gulf of Aqaba, the southeastern and the southwestern paths, which in turn represent the Arabian shield geologic province. The group velocity data were inverted to obtain shear wave velocity structure models of both the shield and the platform regions. Damped least-squares inversions method that utilizes a differential rather than stochastic damping was used to obtain smooth shear wave velocity models. The resulting models are in good agreement with previous results obtained from tomographic inversion.