(a) Horizontal vector displacement evaluated at depth 10 km and time t= 20 yr following a strike-slip event. Viscosity in the 3-D heterogeneous volume is η_h= 10¹⁸ Pa s (see Fig. 4). The fault plane is marked as a gray rectangle. Although 1024 vectors are available on the 10 km depth isosurface, only every 25th point is plotted. The contour used in employing the representation theorem (eq. 33) is shown as a dashed circle. (b) Vertical displacement evaluated at depth 10 km and at several times following a strike-slip event. The vertical projection of the fault is indicated with a black line segment.