Hi Bob,

Mogi's are always tight-in from what I've seen. Though one might see a circle form in a wide area, I don't think that's what the theorist had in mind. One thing we don't see because of how maps are displayed are three dimensional Mogi's where they are on an elliptical plane and so we would miss them. Dr. Biswas at the Geophysical Institute in Alaska has been studying them for probably twenty years as they apply to Rampart Fault near Fairbanks. The Alaska Science Forum has some pieces on the Internet about Mogi's you might wish to review.

I like everyone else like to find patterns in seismicity and Mogi's are one of my preferred interests. We had one last year just off-shore Long Beach and it filled in with perfection.

I hope this helps a little,

Petra