EM conductivity (frequency-domain EM)
Definition
A non-contact method using a transmitter coil to induce eddy currents in the ground and a receiver coil to measure the secondary magnetic field, yielding apparent conductivity. Instruments like the Geonics EM31 and EM38 cover ground rapidly for reconnaissance surveys.
Related terms
- Electrical resistivity tomography (ERT)
- A method using multiple electrodes on a line or grid to inject current and measure voltage, computing a two-dimensional or three-dimensional resistivity...
- Fluxgate gradiometer
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- Magnetic susceptibility
- A measure of how strongly a material is magnetised by an external field. Topsoil heated by fire or biological activity has elevated...
- Thermoremanent magnetisation (TRM)
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- Wenner array
- A four-electrode resistivity configuration where all four electrodes are equally spaced. Depth of investigation is approximately equal to the electrode spacing. Provides...
Explained in
- Magnetometry and Soil Magnetic SusceptibilityA non-contact method using a transmitter coil to induce eddy currents in the ground and a receiver coil to measure the secondary magnetic field, yielding appar...