Magnetometry is one of the most used technique around the world. It can enable large non-urban areas to be surveyed in a relatively short timeframe with causing no disruption allowing you to delimitate areas of interest. It is used as well to detect specific archaeological features as combustion areas, pits, storage pits, and some more.
SOT offers extension surveys with metal detectors to locate areas with non-constructive structures as battlefields, UXO detection, forensic application and others.
The methodology is based on the georeferenced superficial material collected to create dispersion maps. Using this methodology doesn't allow you to know if the archaeological levels are affected.