Cathryn....Argus published about this zone of contraction a few years ago....but I guess the new paper has much more data in it. I'll have to get the paper...The surprising thing about the results is that the main surface fault that separates the San Gabriel Mountains from Los Angeles Metro ...the Sierra Madre fault, is not the cause of most of this motion. So, it is the blind faults like the Puente Hills fault....but, the published papers on the blind faults under Los Angeles basin include giant flat/gentle faults that link all the way across beneath Los Angeles. Despite the results from Yeats and Levi that were linked on this page by someone a couple weeks ago, I don't think anyone can rule out quakes much larger than M6.7. They would have to be rare, but they would be really ugly...it would get the deep, young, sedimentary fill of Los Angeles basin shaking...waves would be amplified, reflected, etc....(e.g., Olsen and Archuleta, Olsen et al...1995, 1996...
Chris