Canie...why don't you or I ask Roger if he wants to graph your relation. Maybe he could make identical plots of M5+ quakes for different areas for, say, the last 30 years: southern Gulf including some distance farther soiuth, Central Gulf to US Border, then California south of 33.5 N, then California between 33.5 and 35 deg...
The plot would just be date along the horizontal, and quake by magnitude along the vertical...starting with M5 and going up (or, M4.5 or whatever you decide...can't be too small or catalogue will be incomplete).
would you expect this to show anything? If so, Roger...want to take a look at it? Canie...want to revise this suggested way of looking at it?
Chris