The photos aren’t the best but I could use a little help here
The concrete stoop in the back at the top of the steps and in the front had huge gaps with nothing under them. The landscaping was flowing away from the slabs so i have no idea what caused this. The front stoop was settling and cracking because of it and the back was just starting to crack. The gaps were huge. If the entry holes were big enough I could have fit my head in there. When I looked under I could see the the bottom of the gravel that they had poured the concrete on.
What are some possible causes of this and how is it remedied?