SKS splitting analysis of seismic anisotropy beneath mid-eastern Africa

Mid-eastern Africa is a tectonically complex region due to the presence of Tanzania craton，several paleothrust belts and shear zones. The magmatism is active and researchers believe the existence of a mantle plume. Mechanisms and structures controlling the tectonics and geodynamics in mid-eastern Africa remain unclear and the interpretations for origins of anisotropy have not converged. In this paper，by taking advantage of the most recent seismic data of Africa Array，seismic anisotropy beneath mid-eastern Africa is analyzed with teleseismic SKS splitting measurements; we try to explain the sources of anisotropy in a variety of scenarios，such as cracks，magma-filled lenses and LPO (lattice-preferred orientation) of olivine fabrics. Fast polarization patterns at most stations are consistent with tomography based on mantle flow model at the depth of 250 km，inferring that the dominant source of anisotropy beneath this region is LPO of olivine fabrics produced by dislocation creep in the asthenosphere. We attempt to interpret anomalous rose diagrams with D″ anisotropy and double-layered anisotropy. We also discuss the significance for the research of D″ anisotropy.