Petra..Mark Legg has probably thought the most about uplift of Catalina Island....I think he calls it due to a restraining double bend...where the San Diego Trough fault farther south, which is a right-lateral strike-slip fault, splits, with part bending to the west (looking north), where it would probably be called the Catalina Escarpment fault, although I don't know if this fault has been actually named or if it is part of any hazard model. You could get uplift by right-oblique reverse slip on this fault....or, there could be a blind thrust fault...I don't know which Mark Legg thinks it is, and I have not noticed anyone actually doing any kind of geometric or semi-quantitative model of this.
As for a LA quake...it has been published that blind faults near LA could have quakes on the order of M7. One thing to watch out for is that the naming of Elysian Park fault is confusing....Davis and Namson originally named a regional thrust fault this, but it was changed by others to Santa Monica Mountains thrust (which is controversial) with part of it in the east, north and under downtown LA, being now called the Lower Elysian Park....which is probably the one you are interested in. You might be safer to use the Puente Hills thrust (of Shaw and Shearer, 1999)...which is generally now agreed to exist..
Chris