Hi Michael. I was awake, but I'm at Petra's right now. I can't say for sure, but there is a slight chance that the New Britain quake could have triggered this as a far-field aftershock. Petra commented about this last night, but at the time I told her I didn't think it was possible because in the past it appeared the quake had to be in 7.0Md range and above for far-field aftershocks to occur. I also thought the quake might have been a little too far to the south to affect the Central California area. It is possible however that it could have an affect on Southern California.

The area of today's quake is an area we almost always have a quake in the range of that magnitude. Another area is 17 miles south of Hollister. We usually have a quake of that magnitude about every 18 months. If memory serves me the strongest quake was a 4.3Ml. This is also an area where we have a lot of small quakes most of which are never felt. After a quake of this size it will be quake free for a coupe of weeks (after the usual number of aftershocks) then the small quakes will start again. When I get back home I will go over to the Almaden Winery and take a look at the reference marks they have on one of the walls to see how much movement there was associated with this quake. If the quake was on the San Andreas Fault there might be a very small indication.

There would have been an indication of strain build up associated with this, but being as how the Echo Valley data site is down there was no way for anyone to see it. This site is always the site that indicates strain for that area of the San Andreas Fault however there is also the chance that you won't see a strain build up. The reason for this is that there are 3 active faults within spitting distance of each other and as such it take months to determine which fault the quake was associated with. Take Care…Don in creepy, but sometimes shaky town.