Mantle transition zone thickness beneath Afar: Implications for the origin of the Afar hotspot

The velocity spectrum stacking method is applied to receiver functions from stations ATD and AAE to image P-to-S converted phases originating at the 410 and 660 km discontinuities beneath Afar. A transition zone thickness of 244 ± 19 km is obtained, similar to the global average transition zone thickness. This result suggests that any broad thermal anomaly beneath Afar probably does not extend as far down as the transition zone. However, because of the 19 km uncertainty in the thickness estimate, a small thermal anomaly of ~100-150 K at mantle transition zone depths cannot be ruled out.