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Writer's pictureGeoffrey Wade

MFT, WFT and OFT is not subject to the skin effect

Updated: Aug 2

The #mineralfindertechology, #waterfindertechnology and #oilandgasfindertechnology precision or accuracy does not vary with depth.  That's because the #MFT, #WFT and #OFT technology is passive - we don't send signals into the lithosphere, so we are not subject to the skin effect which degrades accuracy with depth.


Now let's explain the two words "skin effect”.


In the realm of electromagnetic (EM), seismic, and ground-penetrating radar (GPR) exploration of the lithosphere (what we call active electromagnetic), the skin effect is a phenomenon that influences how electromagnetic waves or seismic waves propagate through geological materials and reflect back to the surface (for measurement and interpretation).


In electromagnetic, seismic, and GPR exploration, when waves encounter geological materials, they interact with them in various ways. The skin effect specifically refers to the tendency of electromagnetic waves to be confined to the surface (or "skin") of a conductive geological material, rather than penetrating deeply into it. 


This skin effect becomes more pronounced as the frequency of the electromagnetic wave increases.  And you need higher frequencies for greater accuracy and precision.  So, the lower frequencies (longer wavelengths) penetrate deeper, but give lower accuracy, and the deeper they go the more they are absorbed and attenuated so you don't get reflections and data back at the surface where you are taking your measurements.  And you can guess the strength of signal has a bearing on penetration too.  And active scientific instruments don’t generate massive planetary scale signals.


For example, in EM exploration, high-frequency electromagnetic waves tend to travel closer to the surface of the Earth, only penetrating to a certain depth before their energy is attenuated. This limits the depth of exploration and the resolution of the data obtained. In seismic exploration, the skin effect influences how seismic waves propagate through different rock types, affecting the quality and depth of seismic imaging. Similarly, in GPR, the skin effect impacts the depth of penetration and the resolution of subsurface imaging.


Satellite over Earth gathering measurements from the lithosphere

Satellite over Earth showing high and low electromagnetic frequencies

To visualise this, think of shining a flashlight through a window into dense fog (inside the room equates to the atmosphere above ground, the window the surface of the earth, and the fog the lithosphere). The light might penetrate the fog slightly, but most of it will be reflected back or absorbed by the surface layer(s) of the fog. Similarly, electromagnetic or seismic waves encounter resistance as they travel through geological materials, causing them to interact more strongly with the surface layers, and not penetrate to depth.


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