earthquakes occur in a circular pattern over decades, building up to one very large temblor in the doughnut hole.

Seismologists call the possible pattern a Mogi doughnut. It's the outgrowth of a concept, developed in Japan, which holds that earthquakes sometimes occur in a circular pattern over decades —building up to one very large quake in the doughnut hole. Rundle and his colleagues believe that the recent quakes, combined with larger seismic events including the 1989 Loma Prieta and 1994 Northridge temblors, could be precursors to a far larger rupture.


[link to www.standeyo.com]

interesting..... start a map of all earthquakes