Hi all;

I've done this before by comparing distance to smaller quakes after a main shock.

This time I compared the distance to the next main quake following each main quake. I used the NEIC catalog from 1973 to 2011 for all mag 7+ events.

For each quake I computed the distance to the next quake and added it to the running total for each degree. When all quakes were tallied the results were plotted on a graph.

There was no favored distance(s) shown by this process except for the very near range which was 4 times larger than the rest. Apparently large aftershock are common.

Roger