Roger-there is a paper in Physics Today about distant triggering of volcanos by earthquakes and vice-versa. Members of AGU receive Physics Today as part of their membership. Its Nov 2002, p. 41-..., by Hill et al (USGS). Their Fig 2 b shows a clear graphical example of how to show a relationship. In other words, my suggestion of how to do it may not be the best one-you could just do Moment release or number of earthquakes for all New Guinea area quakes over M7 back as far as catalogues are reasonably complete.

I just took a glance at Lowell's thesis and looking down his figure list did not see the New Guinea-California relation, although it may be there. I recall the New Guinea side was more centered near New Britain. I suppose you could choose a box that includes New Britain, New Ireland, and New Guinea, and a little around that.

I may look at this again when I get by a Tuesday deadline.
I'll repost the mention of the Physics Today article after I finish reading it and after Tuesday-it is rather Lowell-like stuff.
Chris