These are tightly clustered around two injection wells. For a while, I had thought the lake had something to do with it. There appears to be no mechanism associated with these, so it probably isn't close to a megathrust, unlike the first Arkansas sequence. Nevertheless, they are injecting into the Precambrian, so things can happen. Personally, I would just let these things go, and try to get more scientific information, such as time histories of flow and pressure.