These images are examples of “Level B Foundation Surveys”. Essentially, this is the “topographical map” produced from the Zip Level readings taken from a foundation. As you can see, there are heaves (areas of gradient lines close together around a central area) that look like little hills in the foundation. In North Texas, these heaves are usually (but not always) caused by water. A common source of water under a slab is failed cast iron sewer piping used in pre-1983 construction. I have personal experience in which a slab indicating a heave was the result of a eroded sewer line that cost $8000.00 to fix…luckily it was identified in the home inspection and negotiated during the option period.