Figure 6. Snapshots of wave propagation for the M 5.3 Alban Hills scenario in Rome. The snapshots depict particle velocities at 10-sec intervals after the origin time of the earthquake. The thick line shown on the snapshots is the 50-m-depth contour of the isosurface of V_s = 250 m/sec and depicts the outline of the valley. The particle motion is scaled by the same constant for all snapshots.