Sp Receiver-Function Images of African and Arabian Lithosphere: Survey of Newly Available Broadband Data

Abstract

Abstract The growing quality and improving spatial coverage of broadband seismic stations on the African (Nubian + Somalian) and Arabian plates motivate us to present a catalog of S-to-P receiver functions (SRFs) from southern Africa to northern Arabia. As in North America where the ability to compare data from cratons to modern rift provinces has led to new insights about lithospheric discontinuities, so, too, in Africa and Arabia can we begin to track and study the Moho, midlithospheric discontinuities, and the lithosphere–asthenosphere boundary (LAB) between tectonothermal provinces and beneath plate boundaries. We utilized 1508 seismic stations recording 9349 teleseismic events to calculate 103,878 SRFs that we stacked in 1° circular bins. We find a robust positive arrival due to a seismic-wavespeed increase downward across the Moho in virtually all our stacked SRF traces at 15–55 km depth, and we verify this is in good agreement with previously published Ps results, thereby validating the quality of our data set. Our stacked SRF traces also show a sub-Moho negative arrival at a delay time equivalent to 50–132 km depth that should correspond to a negative velocity discontinuity at or above the LAB. Our continent-wide, plate-scale database offers the opportunity to explore for spatial and temporal evolution of lithospheric parameters.