I'm glad you posted these pics. They show what happens to SO-type cord when it is buried.
People seem to think "if it can go outside, it can go in the ground." We see here how burial- under even a little detritus- can degrade the rubber, and in a relatively short time. I have removed cords that had ALL the insulation completely gone because of this.
One way to identify the problem is the presence of dead vegetation- current leakage will kill grass, plants, etc. in the immediate area.
It should also be noted that your typical cast zinc "Bell" box will also quickly self-destruct when in contact with the ground.

Aren't "bell boxes" made of aluminum?

For some reason in NorCal, rabbits go nuts eating ST/STO/SJT PVC-cable jackets (like it's bunny aphrodesiac or "bunny-nip".}

In the first pic, it looks like the bare conductor is exposed on the black wire,Also what is that 3 conductor romex for that goes nowhere in the last pic?

Say this is a service? Hope it's protected in some way. And looks like the only attempt to bury it was done by wind blown debris.

Scott, my cannondale (Bike) is aluminum, I have no idea what crap they use to make bell boxes with. Mirical-multi-metal(TM)?