This model is for a P wave only, so it is not comprehensive view of how FZTW travel, but it is a good insight.

You can see how once a wave leaves the fault zone, it travels as an ordinary wave, whereas the waves trapped within the fault zone are constructively interfering and creating a large wave packet.

Inside the fault zone, which is marked by dashed lines, wave fronts are retarded by the low-velocity material. Outside the fault zone, circular wave fronts are spreading out as they propagate in the homogeneous medium. A sequence of wave fronts of diminishing amplitude follow the leading wave front. A small portion of the energy leaks out of the fault zone.