Use of electric potential difference in audio magnetotelluric (AMT) geophysics for groundwater exploration

Abstract

Due to recent advancements in technology, a variety of Audio Magnetotelluric (AMT) geophysical equipment using electric potential difference (V) as the main parameter for groundwater exploration is now in use. Studies on the application of electric potential difference in Audio Magnetotelluric Geophysics for groundwater exploration are yet to be published. This paper primarily provides an overview of the theoretical background on the use of the electric potential difference in Audio Magnetotelluric geophysics for groundwater exploration and shares recent field results from the application of the technology. In the field test, analysis of the lithology data collected during the drilling of two groundwater production boreholes provides meaning to the electric potential difference data collected prior to the drilling. Results show that the electric potential difference measured with the Audio Magnetotelluric Groundwater Detector correlated with lithology and groundwater occurrence at two observation sites. The water strikes occurred in sandstone formation of various degrees of disintegration and were associated with contrasts of low electric potential differences in the range of 0.005–0.019 mV. The finding suggests that the changes in electric potential difference can be used to delineate potential aquifers and vertical variation of geology. The expectations are that this presentation will stimulate further research to understand the applications of Audio Magnetotelluric electric potential difference technology for groundwater exploration in different hydrogeological settings.