Unknown, that is, to the people who demand scientific evidence! But you and I are above that sort of thing, especially when there is no hope of getting that evidence, as long as the US relies on pork-barrel direct Science funding. Here is a nice long article on interior earthquakes, along with all the usual wrong opinions. :)
This is just a map of Ohio, with their faults. I think they are rather fanciful on the location of the Grenville Front, but, then again, most people are. If they had run some good, deep reflection seismic, they would have picked up the giant Ontario megathrusts that run through their state. Even in this DEM you can see traces of them, but in the US, everything is balkanized into state-only studies, because each of them have their own little state geological surveys. Once you step over the border and involve 2 states, it becomes a Federal matter, and they are only interested in California!
One day, after a monster earthquake, you might get a decent regional study, following the big megathrust faults, and their eventual fate in the US, as they grind up against the Rockies.