Frequency-Domain Electromagnetics (FDEM)
Frequency-Domain Electromagnetic (FDEM) is a noninvasive geophysical technique that operates by transmitting an alternating current (AC) through a transmitter coil to generate a primary magnetic field, which penetrates the ground and induces eddy currents in subsurface materials. These currents in turn create secondary magnetic fields that are detected by a receiver coil. The returned signal, analyzed in terms of its in-phase (sensitive to magnetic susceptibility and metallic objects) and quadrature (indicative of electrical conductivity) components, allows for mapping variations in subsurface conductivity and magnetic properties—enabling rapid, high-resolution surveys via ground, mobile, or even aerial platforms without physical contact with the surface
Applications
- Mineral Exploration
- Detects conductive mineralization such as dyke- or lens-type ore bodies, especially those associated with sulfide deposits, to depths of up to 50 m in favourable conditions.
- Helps outline shallow conductive structures and supports resource evaluation by providing subsurface conductivity contrasts.
- Groundwater and Hydrogeology
- Locates conductive faults and fracture zones that may channel groundwater.
- Assesses water table characteristics and identifies saline intrusion in aquifers.
- Environmental Monitoring & Contaminant Detection
- Maps contaminant plumes such as leachate from landfills or industrial waste sites, revealing zones of increased conductivity.
- Detects buried waste—metal drums, storage tanks, or other subsurface infrastructure—via their conductive signatures.
- Geotechnical & Engineering Investigations
- Maps moisture anomalies and lateral changes in soil saturation—for example, detecting seepage in dams, levees, pipelines, or containment walls.
- Identifies buried utilities and metal objects like underground pipelines and storage tanks; effectiveness depends on material (e.g., metallic objects respond strongly, while PVC does not unless accompanied by tracer metals)
Partner with SLA Geophysics to leverage FDEM and complementary geophysical services tailored to your project needs. Contact us today for a free quote, and let's uncover what lies beneath—efficiently, accurately, and responsibly.
