More complicated electromagnetic methods can be applied to not only detect the presence of subsurface metallic objects, including unexploded ordnance (UXO), but also to characterize those objects, allowing for discrimination between genuinely dangerous materials and benign scrap. This process, known as Advanced Geophysical Classification (AGC), provides a valuable service in reducing the number of possible UXO targets at a given site, thereby reducing the cost of dig operations.
Multiple electromagnetic coils are used in tandem and orthogonally to collect data in three dimensions. During processing, the data is compared to an established library of known responses to various munitions. Data analysts can then determine which items most likely pose a threat to human life and so merit removal.
Developed under the supervision of the U.S. Army Corps of Engineers (USACE), and having been successfully employed in categorizing thousands of potential UXO targets, AGC has become an essential and reliable tool of modern geophysical work.