Comparing the Effects of GPS Error on Different Electrical Resistivity Tomography Arrays for Archeological Investigations

Abstract

An optimal reconstruction of the soil for archeological purposes is mandatory. Dimensions and depth of buried anthropogenic remains must be identified accurately allowing an easier design of the excavation survey and minimizing the excavation costs. Electrical resistivity tomography (ERT) is a widely used geophysical technique to measure the resistivity of the ground at different depths, and then reconstruct the underground stratigraphy. Misplacement of the electrodes is a fundamental aspect of these measurements because it could lead to incorrect data analysis. Regardless this issue, recent literature misses to consider the influence of the global position system (GPS) error in the localization of the electrodes on the final subsoil electrical resistivity distribution. In this article, the results of a measurement survey on the Poggio Pepe tumulus (Italy) were analyzed and a Monte Carlo (MC) simulation was carried out to investigate the influence of the GPS accuracy. The MC approach has been applied to two different kinds of ERT arrays: pole–dipole and dipole–dipole. Firstly, the simulation considers the ideal in-line position of the electrodes affected by the GPS error, then the real coordinates of the electrodes are introduced, together with the GPS uncertainty. The simulations provide interesting findings on how the GPS error influences the two arrays and the use of the topography. Moreover, the proper deployment of the remote pole for the pole–dipole array is discussed.