John;

What you say is certainly true. But if you look at a plot of the various P phases on a cross section of the earth you can see them grouping at the ring distances. The start of the shadow zone is quite clear in that respect.

The triggered quakes are expected to be an order or more smaller than the triggering quake.

Still, it's not my theory and Lowell is not posting any more. It's probably part of the GeoF. procedures as well.

Roger