MS wrote: The 'wave' is something that I've 'seen' a number of times while I was in the bay area. It's always amazed me when I would search for the damage caused by a 'wave' passing through concrete slabs, or other material objects that I would consider inflexible. Never found it, and after, would hold the theory that the quake caused aberrations in the light waves, rather than in the inflexible matter. FM: That is fascinating. I've seen the 'wave' a number of times when I lived in LA. How would seismic waves interact with light waves?