Seismic evidence for a deep upper mantle thermal anomaly beneath East Africa
Upper mantle seismic velocity variations beneath northern Tanzania coupled with the structure of the 410 and 660 km discontinuities reveal a 200-400-km-wide thermal anomaly extending into but not necessarily through the transition zone beneath the eastern branch of the East African rift system. This finding is not easily explained by small-scale mantle convection induced by passive stretching of the lithosphere or by a broad thermal upwelling extending from the lower mantle into the upper mantle, but it can be attributed to a mantle plume, provided that a plume head is present under the lithospheric keel of the Tanzania craton. A plume interpretation for the deep thermal anomaly is supported by evidence for mantle having the geochemical characteristics of a plume at >150 km depth beneath northern Tanzania.
Nyblade, A., Owens, T., Gurrola, H., Ritsema, J., & Langston, C. (2000). Seismic evidence for a deep upper mantle thermal anomaly beneath East Africa. Geology, 28 (7), 599-602. https://doi.org/10.1130/0091-7613(2000)28<599:SEFADU>2.0.CO;2