Hi Roger, I'm slow to thank you for your efforts because I wanted to spot check some things and did not get around to it.

Your results show nothing going on (about the quakes you would expect by chance).

But, you only had 1 M9 so I checked the Japan quake and indeed, including the M7.4 foreshock, there were six M6+ quakes scattered around the globe between March 6 and 10.

OK, let me check Chile 2010: OK, only two in the week before.

Alaska 1964...none, because the catalogue I chose starts at 1973....

OK. Sumatra 2004: only two but one of these was a M8.1 four days before.

At this link: http://earthquake.usgs.gov/earthquakes/eqarchives/epic/epic_global.php
(also linked below)

Chris

• earthquake search