What causes the ground is lifting up around my tree?

Anchorage fails when the soil cannot hold the root plate or the plate is too small to begin with. Saturated soil after prolonged rain sharply reduces holding capacity, which is why wind a tree survived for thirty years takes it down after a wet week. Roots severed on one side by trenching, a new driveway, a utility line, or a foundation dig remove the tension side the tree was relying on. Root rot destroys anchoring roots invisibly while the canopy still looks healthy. Deep planting, and a tree that grew up sheltered and was suddenly exposed when neighbors were removed, both leave undersized or shallow root plates.