Illustration of seismic (a) and thermodynamic (b) model parametrizations, respectively. (a) Profile of shear modulus (μ), where dots indicate segments and nodes that are variable in elastic properties and depth, respectively. (b) Geotherm (magenta) where the adiabatic mantle is overlain by a 150 km thick, conductive lithosphere with basal temperature of 1350 °C. Free thermal parameters are indicated by dots. The associated S-wave velocity (⁠|$\rm V_S$|⁠) profile for a pyrolitic mantle is plotted in black. See Table 2 for an overview of all model parameters.