Shear Wave Splitting Across Eastern, Western and Southern Africa

Tuesday, 16 December 2014: 11:35 AM
Andrew Nyblade1, Cristo Ramirez1, Brian C Bagley2, Gabriel Daudi Mulibo3, Fred Tugume4, Michael Edward Wysession5 and Doulgas A Wiens6, (1)Penn St Univ, University Park, PA, United States, (2)University of Minnesota Twin Cities, Minneapolis, MN, United States, (3)University of Dar es Salaam, Dar es Salaam, Tanzania, (4)Geological Survey Department, Entebbe, Uganda, (5)Washington Univ, Saint Louis, MO, United States, (6)Washington University in St Louis, Department of Earth and Planetary Sciences, St. Louis, MO, United States
The expansion of the AfricaArray network across eastern, western and southern Africa, in conjunction with seismic data from many PASSCAL deployments over the past 20 years, is helping to fill in major gaps in the global coverage of shear wave splitting measurements. New results from stations in Ghana, Nigeria, Mozambique, Botswana, Angola, Namibia and South Africa are presented in this study that when combined with previously published measurements help to map the pattern of seismic anisotropy over much of the African continent. A general pattern of fast polarization directions, characterized by NE orientations, is found, and superimposed on this subcontinental-scale pattern is local and regional variability, most notably around the Archean Tanzania craton in eastern Africa. The subcontinental-scale pattern, as well as local and regional variations in this pattern, are interpreted in terms of large-scale mantle flow from the African Superplume, fossil anisotropy in the lithosphere, and shape anisotropy in magmatic regions of the East African rift system.