Teleseismic P-Wave Attenuation Beneath the Arabian Plate

Abstract

In order to prove that the Arabian Plate is a tectonically active region even in its shield areas, we obtained the attenuation structure tp* of the upper mantle beneath the Arabian Plate by applying the spectral inversion method to the newly established seismic network in Saudi Arabia operated by the Saudi Geological Survey (SGS). The data sets consisted of good quality vertical components of the teleseismic events for more than 4400 spectral ratios. The result showed significant and diverse tp* structures between the eastern and western regions of the Arabian Plate. High tp* was the predominant feature underneath the Arabian Shield (western Arabia) and low tp* within the Arabian Platform (eastern Arabia). The obtained tP* values range from −1.0 s to 1.0 s. The observed high tp* patterns followed a line from north to south through the Arabian Shield along the Red Sea margin. The high tp* distribution closely followed the volcanic region, in particular the Makka–Madina–Nafud Volcanic (MMNV) line. The maximum tp* values were observed in the southern region of the Arabian Shield, at the southern part of the Red Sea, where the African and Arabian Plates diverge. The observed high tp* will be attributed to the previously revealed low-velocity anomaly and thermal activities beneath the Arabian Shield, and it is also correlated with the topography (high elevation) in the region.