Looks like you are just beyond building limit of stone alone, probably doesn't have a short enough path to ground. I would make sure your all your wood iron poles are tied into other wood iron poles and not just on the stone. Looks like a few of them at the top are only attached to the stone, I'd tie those in to the other wood iron poles so they have a path to ground. Looking at it closer, it looks like those areas are where all your breakages occurred.