Crustal seismic structure and anisotropy of Madagascar and southeastern Africa using receiver function harmonics: interplay of inherited local heterogeneities and current regional stress

Summary This study investigates the seismic structure and anisotropy in crust beneath Madagascar southeastern Africa, using receiver functions. The understanding of is essential for imaging past present deformation lithosphere–asthenosphere system. In upper mantle, mainly results from orientation olivine, which deforms under tectonic (fossil anisotropy) or flow processes (in asthenosphere). crust, crystallographic alignment amphiboles, feldspars (plagioclase) micas heterogeneities such as fractures, add to a complex geometry, challenges Earth's shallow structure. decomposition functions into backazimuth harmonics allows characterize orientations lithospheric responsible azimuthally varying signals, dipping isotropic velocity contrasts layers azimuthal anisotropy. By analysing function records 48 permanent temporary stations this reveals significant signals within Africa. At 30 crustal dominates while signature contrast dominant at remaining 18 stations. However, all stations’ show involving both anisotropic more than one source depth. Our calculated are therefore interpreted reflecting either average interplay several sources depending their strength. comparing information between us draw same conclusions regionally: southern Africa our measurements reflect local, inherited structural generated by current extensional stress field imposed southward propagation East-African Rift System. A final comparison with SKS attributed mantle further probes on measurements.