Imaging the topography of the Lithosphere-Asthenosphere Boundary beneath South and East Africa using S receiver functions; a key to understand continental lithospheric evolution in and around active rifting systems

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The aim of this proposal is to study the structure of the mantle lithosphere beneath South and East Africa. No high resolution image of the Lithosphere-Asthenosphere Boundary (LAB) exists yet in this geodynamically active region, although for understanding the global tectonics, knowledge of the complete structure of lithospheric plates is required rather than only the easier accessible crustal structure. This goal will be achieved using the novel technique of S receiver function. This technique employing S-to-P conversions appears promising for detecting the LAB beneath seismic stations in Africa and has already proven its power for mapping the LAB in the tectonically different regions (see enclosures). The recently tested plain summation technique will also be used to determine the complete P and S receiver site Green s function. This technique will serve to constrain P and S multiples from the LAB resulting in absolute LAB depth estimation. Due to the available data from more than 200 permanent and temporary broadband stations in East and South Africa, it is now possible to obtain maps of the LAB topography with so far unprecedented resolution. The results may obtain detailed images of geodynamic processes and significantly improve the knowledge of continental lithospheric evolution as well as deeper mantle processes related to the continental rifting.