Beth...I'm pretty sure you are talking about the Santa Rosa Island fault, which is E-W, and which splits off of the Santa Cruz Island fault just offshore of Christie (sp?) Beach. I've walked along most of it. What are the scary stories? I know about the ground opening up during the 1812 earthquake in Lobo Canyon...this was a landslide (which probably was 1812, but is not proved). The Santa Cruz Island fault connects to the Malibu Coast fault and Santa Monica fault....the length of the whole fault system is about 200 km...so if half broke would be between M7 and 7.5...
Chris