Full-resolution 3D GPR imaging for geoscience and archeology

Contemporary shallow subsurface assessment relies on outcrops, drilling, excavation and sometimes geophysics. Often the information gathered is insufficient to accurately characterize the archeological/geological record and ongoing shallow subsurface processes which affect a variety of economic and environmental aspects of our society. The extra effort of acquiring very dense ground penetrating radar (GPR) survey grids and 3D data processing transforms uncorrelatable and uninterpretable GPR signals into clear images of complex shallow subsurface anatomy with an unprecedented resolution. Here we present two examples of noninvasive 3D shallow subsurface imaging. Example 1 images decimeter to meter scale sedimentary structures in a Pleistocene oolite. Example 2 images the fracture network in a Triassic limestone quarry. Denser than quarter wavelength acquisition in combination with 3D migration processing focuses scattered energy and removes out-of- plane reflections. In addition to conventional vertical cross sections, horizontal depth slices and data volume animations reveal previously unseen diagnostic patterns of past human activities, laterally changing depositional processes, and fracture networks including near vertical dipping joints with millimeter aperture.