The two diagrams in the middle row show the variation of the two components of displacement rate: Ux and Uy. In Ux, we see the transition between a distributed shear flow on the left to the discontinuous displacement on the right. To balance the horizontal flow, there is also a minor component of vertical flow as shown with Uy. With elapsed time finite deformation of the block is shown on the lower right diagram. The variation of displacement and deformation along the fault is diagnostic of the stress vs strain-rate exponent of the viscous material.
Relevant Publications
Barr, T.D., and G.A. Houseman, Distribution of deformation around a
fault in a non-linear ductile medium, Geophys. Res. Lett., 19, 1145-1148,
1992.
Barr, T.D., and G.A. Houseman, Deformation fields around a fault embedded
in a non-linear ductile medium, Geophys. J. Int., 125, 473-490, 1996.