Horizontally polarized wave motions generated at the free surface of an elastic half-space by strike slip on a fault plane of arbitrary dip are analyzed. Prior to slippage, the stress distribution includes uniformly distributed tectonic stresses and linearly increasing normal stresses due to the weight of the material. The resistance to slip is approximated by the standard Coulomb model for static and kinetic friction. Slip is nucleated along a line parallel to the surface trace of the fault. The moving edge of the zone of slippage propagates toward the free surface with a constant velocity. The method of analysis is based on the observation that certain field quantities show dynamic similarity. The results include expressions for the particle velocities and the accelerations at the free surface. The distributions of velocity and acceleration along the surface are displayed in graphs for various values of the angle of dip, of the rate of advance of the edge of the zone of sliding, and of time.