Ambient noise tomography in the upper crust of North Harrat Rahat, Saudi Arabia

Abstract

Images of Rayleigh-wave group velocity were derived for the 1–15 s period range that is sensitive to shear wave velocities in the crust of north Harat Rahat, Saudi Arabia. We used a continuous dataset of ambient noise that was processed by applying the technique depending on the Rayleigh-wave group velocity tomography. The dataset comprises six months of recordings extracted from 12 broadband seismic stations in north Harrat Rahat, Saudi Arabia. Using a cross-correlation technique, the Rayleigh waves have been generated and stacked along the whole time series. Dispersion curves representing fundamental mode Rayleigh waves were derived by a multiple filter technique. Dispersion curves for each station pair were inverted to obtain the one-dimensional model of corresponding shear wave velocities. The spatial distribution of shear wave velocities was depicted from the inverted one-dimensional models at 138 nodes and a reliable resolution was spatially resolved using grid cells of 0.2° expanded over both latitude and longitude. Images obtained from this study improve our understanding of the tectonic development as influenced by magma upwelling beneath the Arabian Shield. Results obtained from this study revealed two low-velocity zones in the upper crust at depths of 15 km west and shallow 10 km east, respectively. This suggests that high conductivity is present as a result of upwelling magma that flows into the upper crust of Arabian Shield coming from plausible deep sources such as the Red Sea Rift or the Afar plume, which are located to the west of the studied area.

Keywords

• Rayleigh waves
• Magma flow
• Arabian Shield