Sorry, Nova, I thought it was a more common term. One of my geology instructors (lo these many years ago now) used that term, and it's stuck.
The "Elbow" is the area around Frazier Park, inland from Santa Barbara. It's where the north/south line of the SAF bends slightly towards the east, and then continues down into Mexico.
It's a spot that a lot of folks historically believe will be a fracture of the transform fault will break in a catastrophic eq, because at some point in the past, for it to have bent east like that, there was a fracture there. Almost like the bottom is pushing up past the top, even though this is not a thrust fault.
There are also a whole lot of "little" faults in the San Fernando Valley, on an east west orientation, and those may be remnants of an earlier fault break at the elbow, or stress faults from the lower part of the state creating pressure on the area of the elbow.
Hope that makes some sense...thanks for asking. I didn't realize that it wasn't as common as I thought it was. I'll do better next time.
Best-
Herding Cats
