This is an amazing system, much like the New Madrid continental earthquakes in the 1800's. Right now I have no idea if a third earthquake is required to fill it in, like New Madrid. Both mechanisms are exactly the same, so we have to wait for the gps and strong ground motion.
As for the effect, we expect an amplification of a factor of 10 for the deep basins.
Just looking at it, I expect another big earthquake to make it complete, or stress-relieved for the next few hundred years. Two strokes aren't usually enough. But we can hope there isn't another one.