Arizona has so depleted the water under the desert since 1950 it is unbelievable.

When I lived there in the late 1970's a just retired hydrologist for the Tucson water dept lived next door. In 1950 the water table was about 40 feet under the desert around Tucson ... by 1978 it was 300' and I recently read that it is now about 600' (no confirmation as to that last number though).

Pump that much water out from under the soil ... and voila it should be expected that cracking will occur.

The AZ could be something more serious than water depletion under the soil ... but it is hard to tell at this point