One set of clues that you may have considered using to see through the apparent problems with the activity above is the topography of the Los Angeles basin -- the mountains, hills, and valleys present in the area. Low-angle faults (including some blind faults) can alter the surface, creating plateaus and hills by gradually uplifting a region. When such an uplifted area can be found prominently on one side of a fault, while the other side is low-lying and basically flat, there is a fair probability that the fault has a non-vertical dip, and so epicenters positioned off the fault trace are quite possible. Also, a belt of hills with no associated fault trace is an excellent signal that there may be a blind fault at work beneath those hills. You may wish to go back to the Los Angeles basin map and review the distribution of the earthquakes with these possibilities in mind.
With all these warning signs, you might begin to wonder whether the topography of an area can act as an indicator of earthquake risk, even if or especially when the faults in the area are not well-studied.