Thought I'd start a new thread as the old one is getting long and here I talk about geology/geodetics of the area. These Simi-Valencia earthquakes look to be towards the west end of the Northridge aftershock zone from the SCEC map (someone should check me here). They also plot just south of the surface trace of the Oak Ridge fault, which is a S-dipping reverse fault in this area. So, they may be on or close to the Oak Ridge fault. The Oak Ridge fault would have been brought closer to failure in this area by the Northridge earthquake (which was on related faults). The Oak Ridge fault forms the southern boundary of Ventura basin (structural basin). GPS geodetics show 6 or 7 mm/yr of contraction across Ventura basin in this area. Cross sections through oil wells and paleoseismology show the Oak Ridge fault and especially the N-dipping San Cayetano fault to be rather active (Oak Ridge as high as 5 mm/yr in last 1 million, San Cayetano as high as 10 mm/yr in last 1 million). Either fault would be capable of a Northridge-sized event or larger. But, I recall (again, someone check me on this) that there have been earthquakes about this size in this area in the last couple of years without anything following. A M3 earthquake is south of Santa Cruz Island in the last 2 hours is also showing on the SCEC map-we'll see if this is real. Anyway, these earthquakes are at the edges of my research area. I'll be checking the SCEC map every time I log on here for a while to see what else pops up in SOCAL....would not be surprised to see other areas of SOCAL pop with M3s-Chris