CSAMT Method

The CSAMT method (Controlled Source Audio-frequency Magnetotelluric) builds on the Audio Magnetotelluric (AMT) and Magnetotelluric (MT) methods.  Their main applications are for mineral/oil/geothermal exploration, geologic mapping and groundwater investigations.  These methods scan a range of frequencies so that, with post processing, a depth section resistivity model of the ground can be produced.  The main benefit of the magnetotelluric methods is that depth penetration can be quite significant. 

The AMT and MT methods measure fluctuations in the natural electric and magnetic fields over a broad range of frequencies.  These fluctuations are caused by ionosphere related solar activity in the low frequency range, and the world wide thunderstorm activity at higher frequencies.  The CSAMT method uses a transmitter instead of relying on natural forces. 

There are advantages and disadvantages for all three methods when compared to one another.  The key advantage for the CSAMT method is that signals are stronger and thus more coherent.  This allows for easier processing and interpretation.  Data acquisition for the CSAMT method is much faster than AMT and MT surveys, which can reduce overall survey costs.   

The key disadvantage for the CSAMT method relates to the “near field”  effect, which distorts the data.  To overcome this, the CSAMT transmitter and receiver separations, orientation and spacings are carefully determined by examining available TDEM or resistivity soundings data. 

Contact ClearView Geophysics Inc. to design, implement and interpret your CSAMT survey for deep exploration.  Also check-out our CSAMT blog entry and this CSAMT case history which includes a comparison of IP/Resistivity and CSAMT inversion model depth sections.


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