Investigation of cable effects in spectral induced polarization imaging at the field scale using multicore and coaxial cables

Abstract

The spectral induced polarization (SIP) method has emerged as a well-suited laboratory technique to characterize hydrogeologic and biogeochemical parameters in soil samples. However, field applications of the SIP imaging method are still rare, which can be attributed to the particular care required to minimize the contamination of the data by electromagnetic coupling. To date, field procedures rely on the use of two different cables separating the current and potential dipoles to improve the quality of the SIP readings, although this increases the efforts in the field and might reduce the depth of investigation or the spatial resolution of the data. To overcome these limitations, we have investigated the use of a single coaxial cable, as an alternative to improve data quality and simplify field procedures. We evaluate SIP imaging data collected with the same measuring device using a coaxial cable and a combination of multicore cables of different lengths and manufacturers. Data sets collected with a single coaxial cable reveal a significantly lower number of outliers and a high spatial consistency between the phase-lag readings, even for measurements collected with a coaxial cable five times longer than the length of the profile. Furthermore, the data collected with coaxial cables reveal an improved quality for deeper measurements (with a lower signal-to-noise ratio) in comparison to data sets collected with separate cables. Our results demonstrate that the use of coaxial cables might permit the collection of SIP readings with high quality and similar field procedures to those used in resistivity surveys.