I don't have nice precise records of any correlations - I do know it was true before the 1999 Hector Mine quake and already knew of the relationship then..

It's just a pattern I've observed over the years (and years) of watching quakes and living in southern california -

It's more typical that there's something a bit further south first along the plate boundary by central americal and the cocos plate, then up in the Gulf, then up into Southern California - being as the Gulf quakes are strike slip along the plate boundary, I think stress gets transferred up north to the San Andreas boundary.. just gives it that added stress to trigger something more here..

And then again.. maybe nothing.. But usually within 0 to 10 days following the Gulf quake...

One other thing - I don't have a latitude, but it is the quakes more northern in the Gulf.. like this one is only 500 miles or so from San Diego.. that's probably the southerly limit -

I hope your trip in Southern California is not an exciting one Penny!

Canie