oa A combined Gauss-Newton and quasi-Newton inversion method for the interpretation of apparent resistivity pseudosections

Two-dimensional (2D) electrical imaging surveys (Griffiths and Barker 1993) are now widely used to map areas with moderately complex geology where conventional resistivity sounding surveys do not give sufficiently accurate results. In more complex areas threedimensional (3D) surveys (Ellis and Oldenburg 1994, Loke and Barker 1996b), which gives even more accurate results but at a greater cost, have also been used.