That is exactly what is happening. The falling debris is damaging the outer jacket of the cable. That is usually where the faults begin. Even though the outer jacket is damaged, I don't believe that should be any reason for the conductors to cause a problem. As long as the insulation on the conductors isn't damaged. This is direct burial cable. It's rated XHHW-2, at 600 VAC, 90 degree C. It should withstand the environment.
I opened another area today with a fault. I found 3 spots that are blown out within six feet. One of which is a splice I made last week. A very good splice to boot, and 2 conductors were melted together at the connections. This was in between two other areas about 18-24 inches on either side.
Thanks for the input, Merlin
