As I understand the theory, Don (correct me if I am wrong), larger earthquakes
can be triggered when when the seismic wavefront from a teleseismic event
affects the entire fault system simultaneously rather than piecemeal. This creates
a sudden impact on the entire fault along which a moderate or large earthquake
can occur. The regions which have wave fronts parallel to the San Andreas and which
are seismically active, are fairly limited, and include the SW Pacific (Tonga/Fiji;
New Zealand, Macquarie, Vanuatu, Solomon, New Britain) and on the other side
Greece, Turkey and Sicily. For the section of the San Andreas which bends
north of L.A. the regions most likely to trigger a moderate quake would be the
Caspian Sea, Iran, Afghanistan, New Zealand, and the Macquarie Islands region.
Of course any effects would be amplified at the right distances.