Hello Roger, I had a thought on a project...if you are interested. I, as usual, won't do anything with it, am just curious (I would look at it).
Graph all the M5 and larger quakes along the Sumatra and north subduction zone...from maybe 10 deg north to 7 deg south (from subduction zone maybe 200 km east?). From beginning 2004 to end 2007. It would have to be plotted by, say, 1 deg bins of latitude......Hmm...how would you do that on a 2D plot....date on the horizontal axis, latitude on the vertical, and symbols sized by magnitude at the correct latitude-date location. This should show how/whether the September 2007 M8.4 and 7.9 increased seismicity north of the equator. It may show other things. For example, the Andreanoff M7.2 the other day in Aleutians seemed to have foreshocks in the M5 range.

There will be very large numbers of M5+ quakes as aftershocks or the M9.2 and 8.7 and 8.4 in the days afterwards.

If you choose to do this, can you post the graph on the page so all can see it?
Chris