Recent developments in shallow‐depth electrical and electrostatic prospecting using mobile arrays

Abstract

Application of mobile electrical and electrostatic quadripoles during the past ten years has allowed a considerable increase in the size of the surveyed areas, together with keeping a high spatial resolution and a reduction of the total cost of a survey. Two new developments of towed arrays are illustrated here: (1) a pole‐pole array pulled by the operator provides a lightweight solution for mapping large surfaces at a unique given depth of investigation, as shown by the prospection of the Roman‐British city of Wroxeter; and (2) a multipole, multidepth system allows a 3-D investigation of the ground resistivity, as illustrated by the experiments undertaken on the test site of Garchy and on the archaeological site of Montbaron (Indre, France).

3D Inversion of Automated Resistivity Profiling (ARP) Data

“…Additionally, the need for conducting high-resolution surveys characterized by a small measurement mesh and reducing as mush as possible the survey cost without limiting the extent of the investigated area, has led to the development of mobile quadripoles allowing continuous measurement while moving (Panissod et al, 1997(Panissod et al, , 1998. Th ese multi-electrode devices allow measurements over several depths of investigation in order to perform an exhaustive 3D exploration.…”

Detection of metallic and plastic landmines using the GPR and 2-D resistivity techniques

“…However the recent technical improvements in the technique using the advanced continuous profiling (dynamic system) make the system applicable for landmine detections as at least confirmation tool for the suspicious cleaned regions (El-Qady and Ushijima, 2005;Chruch et al, 2006). The coupling in the dynamic system can be achieved through capacitive electrodes coupled carpet pulling on the ground surface without any needs to insert the electrodes into the ground (Gerard and Tabbagh, 1991;Shima et al, 1996;Panissod et al, 1998). Landmine detection using electrical resistivity imaging technique is based on detections the perturbations in subsurface conductivities caused by buried landmines at shallow depths.…”

Capacitive Resistivity Imaging with Towed Arrays

“…Key advantages of CR are that (1) the measurement is unaffected by the nature of the surface material, (2) high signal-to-noise ratios are achievable in resistive environments and (3) the technique facilitates a dynamic mode of operation, in which data are acquired continuously from a towed sensor array. Such arrays consist of multiple capacitive sensors (current and potential dipoles) in a fixed geometrical arrangement, mounted on some kind of mobile mechanical platform, for example a trailer, frame, mat or carpet (Panissod et al, 1998). The entire unit is then pulled along manually by an operator or towed by a vehicle, so that sensors are moving at constant separation.…”

“…Some electrode configurations are generally unsuitable for towed capacitive arrays. The use of remote electrodes (pole-pole and pole-dipole arrays) is common practice in DC resistivity and such arrays have been used for mobile DC surveying (Panissod et al, 1998). However, the length of wire connections to the remote poles prohibits their use on towed capacitive arrays due to the large capacitances associated with long wire segments.…”

“…A small number of commercial instruments (e.g., Møller, 2001;Pellerin et al, 2003;Chouteau et al, 2004) and research prototypes (e.g., Shima et al, 1996;Panissod et al, 1998) …”