Magma deep in the earth that pushes the faults along is not how faults work except near volcanos...so this is not have fault works in southern California or the Bay area. Don can explain how they work...I have to go play hockey and then work on my AGU poster(s). I don't see why there should be any difference in what day of the week. One difference is that people in Colorado do not work on weekends, so the global NEIC list only gradually gets caught up during the following week. Also, lulls like we see on the California map, IMHO, last more than 2 days...they tend to last several days. But, sometimes that map is not working either, and it is less likely to be fixed quickly on a weekend.

I think it would be more interesting to find a complete catalogue...probably meaning M3 quakes and larger, get rid of aftershocks, and compare a couple of areas and see how they respond...number of quakes per day...compare northern California to southern, or even San Simeon aftershocks to Parkfield aftershocks...

Chris