The detection of underground cavities using geophysics is part of a risk reduction process, thus reviewing the integrity of the terrain before moving heavy equipment overhead such as cranes. It is also used to delimit the extent of possible underground voids and subsidence for repair planning.
The georadar makes it possible to study the first meters of geological layers and determine the location and extent of underground cavities, sinkholes and subsidence. The use of the georadar is recommended at the slightest sign of subsidence, such as potholes in clay and cracks in harder materials. However, in cases where the surface is firm and supports its own weight, the material below may sink until a significant void has developed under the surface layer with no visible warning signs. The surface can break when heavy loads are applied or, if the vacuum reaches a size where it can no longer support its own weight, collapse on its own.