According to SCEC's significant quakes and fault interactive map, that is the Sand Hills Fault. Although, it does follow the path the San Andreas was taking before it 'ended' at the Salton Sea.

http://www.data.scec.org/significant/index.html

Needless to say the area is complex, being the northern terminus of the East Pacific Rise. The Brawley Seismic Zone is considered a spreading center.

There has been volcanic activity in the past. An area along the south shore of Salton is known as the Salton Buttes, active 8500 years ago, resulted in several rhyolite lava domes.

http://en.wikipedia.org/wiki/East_Pacific_Rise
http://en.wikipedia.org/wiki/Brawley_Seismic_Zone
http://en.wikipedia.org/wiki/Salton_Buttes

Brian