The current earthquake activity in southern CA has been affected ever since the Hector Mines quake of October 1999. Take a look at the volcanic backbone or spine of California from the Salton Sea area northward to Mammoth Lake. The ULF activity is centered right now upon Coso, but it's been from the Salton Sea all the way up to Long Valley and Mammoth. Something is up, the recent waveforms from Mammoth and Long Valley EHZ sensors indicate that, but I don't think it is time to call an alarm.

The last 3 months have seen extensive activity, especially since the last week in June when things seemed to take off. You might like to read some of Frank's posts on the 1 AE ionospheric phenomena which showed interaction of the LA basin ECFZ with the F2 layer overhead. Just the last three days has seen a complete change of the previous weeks behavior.

We'll just have to watch very carefully and see.