Cathryn;
Ripe is definitely the right word for it as Glen said. The are has been off and on again last few months and is certainly due for something over a 5Mw. You gave it quite the window of time...which considering how long it has been since something significant, is probably a good idea. I am betting on subduction which might mean a bit north of the MTJ and not too far off shore or possibly on shore. Bets are off as to whether it would be called a 17 year afteshock:-)