ABOUT THE TALK

The Audio Magnetotelluric (AMT) signal is generally in the range of 1Hz -20kHz with its origin as spherics created by thunderstorms, magnetospheric noise, seismic eventsetcHistorical AMT monitorsup to five channels at each station, namely Ex Ey Hx Hy Hz. The EM field is a plane wave perpendicular to the ground surface, away from the field source. Approximately 1-2 hours was required for a layout / recording/pickup cycle which meant that 8to10 stations per daycould be surveyed. This has improved with newer equipment.Normally post processing and editingis done in the office using Cagniard’s AC Apparent Resistivity and Skin Depth formulaeto achieve a !D depth inversion. PQWT premise: Becausethe magnetic field component is basically stable in most scenarios, small in the area of measurement, it will be regarded as a constant function of the Ex responseA discussion with field examples is made that as the Hy field is small and stable,using aconstant will result in faulty readings only on complex structures.If the assumptions are met, good data can be obtained.Price difference of $2,500 against ~ $50,000 for a full AMT set.Groundwater and reconnaissance exploration requires a lower level of precision to make an interpretation.

ABOUT THE PRESENTER

Ray van Rensburg is the Managing Director of Geotron Systems, a geophysical manufacturing company, together with its predecessor Chemtron, has been building geophysical equipment since 1971. Geotron was founded in 1987 after the buy-out of the geophysical business from Chemtron. Geotron also operated a contracting / consultancy division for two decades. Considerable expertise has been acquired in both advanced electronic methods and applied geophysics during this time. He is a registered Geophysicist and has been a member of SAGA since 1988.

TALK RESOURCES

• Presenter's Talk pdf_RvRensburg_GEOTRON_AT Receiver_SITING (PDF, 6,26 MB)
• Recording available via the GWD YouTube Channel