I going to say that all evidence points to slab pull here. That means the oceanic slab is cold and sad, and wants to die. So the deep part is pulling the rest. It recycles and forms volcanoes. Resisting that is the friction of the big active strike-slip fault, which tugs back. The sticking points shear off with M7+ earthquakes. I am looking for one more at the circle.
When that happens I expect an M9 along the whole strike-slip. It will probably not produce a great deal of PGV under civilization, since there is a lot of weak oceanic crust. No tsunami either. It will set up the next great slab M9 in the next 50 years.
So, the proof of the pudding is my M7+ in the next year or so. As with the others there will be no warning, since the fault is glass smooth, and it won't do much. Such interesting things!