Electrical Resistivity Tomography: A Subsurface-Imaging Technique

Abstract

Electrical resistivity tomography (ERT) is a popular geophysical subsurface-imaging technique and widely applied to mineral prospecting, hydrological exploration , environmental investigation and civil engineering, as well as archaeological mapping. This chapter offers an overall review of technical aspects of ERT, which includes the fundamental theory of direct-current (DC) resistivity exploration, electrode arrays for data acquisition, numerical modelling methods and tomo-graphic inversion algorithms. The section of fundamental theory shows basic for-mulae and principle of DC resistivity exploration. The section of electrode arrays summarises the previous study on all traditional-electrode arrays and recommends 4 electrode arrays for data acquisition of surface ERT and 3 electrode arrays for cross-hole ERT. The section of numerical modelling demonstrates an advanced version of finite-element method, called Gaussian quadrature grid approach, which is advantageous to a numerical simulation of ERT for complex geological models. The section of tomographic inversion presents the generalised standard conjugate gradient algorithms for both the l 1-and l 2-normed inversions. After that, some synthetic and real imaging examples are given to show the near-surface imaging capabilities of ERT.