We run into this quite a few times. Due to the rust around the hasp and the paint job it is obvious that this is an older installation, Without firsthand observation I would say that settling and frost are the culprit but not the blame. There should have been a ground slip sleeve installed in the utility riser.(Some utilities provide it, some make it the responsibility of the customer. I believe that the code calls for it where this is a possibility of occurring.) Over the years I have found lock rings which have worked their way off, maybe due to vibration or poor installation then the conduit settles to some degree. I would guess that if you opened the base you would find the ring. Our cooperative will address these issues as we come across them due to unprotected and non-fused conductors and the hazard it presents to the public.