Black arrows: the synthetic velocity field v^obs_k at 100 randomly distributed observation sites r_k evaluated for an infinite sequence of past earthquakes (eq. 21) using the random fault network parametrized by {Γ_ν, T_ν, t_ν|ν= 1700}. Different cases correspond to relaxation on the Earth model with viscosity: (a) η_m= 2 × 10¹⁹ Pa s, (b) η_m= 8 × 10¹⁸ 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. Grey arrows: the velocity fields derived from inversion of the synthetic velocity fields, calculated from the corresponding distributions of and in Figs 9(a)-(c) and eq. (8).