The very corner of the cement slab, which forms the floor of my basement, broke off. There was nothing supporting it underneath. the portion that broke off forms a triangle 11" x 10" x 14" x 3-6" thick. The chunk was bordering the concrete footings. The dirt in the hole is soft and loose. At least 6 sqft at that corner of the slab is suspended without support. I'm including a couple photos up underneath the slab. I suspect that there is erosion or settlement caused by water. What would be the easiest way to prevent further damage to the structure for as long as possible? My idea is to dig out as much dirt as possible and then pack the hole with rocks. At what point would excavating the loose soil undermine the support of the footings and slab? Thanks for any ideas or insights you are able to provide.
Here is video for context: https://s3-us-west-2.amazonaws.com/flipt-temporary-storage/foundation_hole.mp4