Ground-penetrating radar (GPR), also known as industrial x-ray,  is a non destructive testing method that uses radar pulses to image the subsurface. This method uses electromagnetic radiation and detects the reflected signals from subsurface structures. Ground penetrating radar can have applications in a variety of media, including rock, soil, ice, fresh water, pavements and structures. In the right conditions, practitioners can use GPR to detect subsurface objects, changes in material properties, as well as voids
and cracks.

GPR