Darn... sleeping in... missed it.

But, I'm not really surprised. This is I believe known as the Anza gap and I recall at least 2 or 3 other near or around mag 5 quakes in this area over the past 15 years or so.

I don't recall the previous aftershock patterns. This one is striking. It is definitely a "vigorous" aftershock sequence.

Although the automated solutions are fairly accurate in SoCal due to the density of the instruments here, I'd expect some of these to get relocated later. But even so, the relocations aren't but by a few miles.

As always, time will tell.

Brian