Figure 4: Profiles of shear-wave splitting parameters across the rift valleys in Ethiopia.

The across-rift profiles show variation in splitting parameters at stations located 100 km either side of profiles x–x′ for the MER and z–z′ across Afar. For both the MER (a, b) and RSR (c, d), note the dramatic increase in magnitude of anisotropy synchronous with rotation of fast direction into the Quaternary-Recent magmatic segments. The top two panels show topography along the displayed profiles.