Electrical Resistivity Tomography: A Subsurface-Imaging Technique

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 tomographic inversion algorithms. The section of fundamental theory shows basic formulae 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 l1- and l2-normed inversions. After that, some synthetic and real imaging examples are given to show the near-surface imaging capabilities of ERT