Hi Stuart. Welcome if you have not posted here before; we are short of people who post. It's good you put the Latitude and Longitude, because when I saw your subject I thought you meant Santa Cruz small city California, or Santa Cruz Island California. I'll take a guess and say you are not from the USA; New Zealand? (by the way you put the date not = USA)

Interesting; maybe Roger would want to graph M6+ quakes. If the area had high M7s or low M8s, maybe it has released most of the stress and accumulated strain and not headed for something much larger. I also don't know the plate convergence rate there. Finally, last fall I heard a talk suggesting that some subduction zones are not capable of M9s. I'm interested in where that might be true. But, seismologists keep getting this wrong: Sumatra 2004, Pacific Northwest-Cascadia (1700), and east Honshu Japan all beinge examples.

But, a short subduction zone or possibly old ocean lithosphere subducting under Ocean lithosphere might tend to go in M8s?

Chris