S-wave velocity variations from seismic inversions. Shown are slices through our interpolated mean model (left-hand panel) at 100 km (a) and 600 km (c) depth, respectively. For comparison, respective slices through the global tomographic model by Durand et al. (2015) are shown on the right (b,d). Perturbations in S-wave velocity, |$\rm dV_S$|⁠, are given in per cent with respect to the global mean at each depth. In (a), plate boundaries from USGS are plotted in green.