Frequency Domain Electromagnetic
Four Oaks Geophysics uses the Geonics EM-31MK2 with a hand held computer system, the Archer 2. This equipment is typically tide to a GPS system to provide complete site coverage and sub-meter accuracy of the recorded elevated responses.
Frequency Domain Electromagnetics (FDEM) can test for soil conductivity changes and inphase (metallic objects) simultaneously. This equipment can then produce a data file that can be contoured using mapping software to identify areas of high metallic concentrations or areas of shallow rock. Unfortunately, this equipment is impacted by high voltage overhead lines so urban surveys due tend to be difficult to conduct.