Distribution of inverted moment release rates derived from inversion of the synthetic data sets of Figs 7(a)-(c) with the EIV model (eq. 8); separate distributions were derived from each velocity field. Different cases correspond to relaxation on the Earth model with viscosity: (a) η_m= 2 × 10¹⁹ Pa s, (b) η_m= 8 × 10¹⁹ Pa s, (c) η_m= 6.4 × 10¹⁹ Pa s. A constant crust-to-mantle viscosity ratio η_c/η_m= 2.5 is assumed. In each case, the roughness term of the misfit function (eq. 26) has been uniquely chosen such that the inverted velocity field yields 97 per cent variance reduction with respect to the synthetic velocity field. Contour lines are drawn (in units of 10¹⁴ N m km⁻² yr) at values −0.1, −0.05, +0.1, +0.25 for and at ±0.05, ±0.1 for ⁠.