Characterization of conductive ground using handheld loop-loop 3D electromagnetic method

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Handheld loop-loop electromagnetic (EM) instruments are being used increasingly for shallow environmental surveys because of their portability. However, in many cases, the quality of data is so poor that quantitative interpretation is not justified. This is because EM data are inherently susceptibility to calibration errors. We have developed an algorithm that simultaneously inverts loop-loop EM data for a multidimensional resistivity distribution and offset errors. By using this simultaneous inversion algorithm, one can determine the resistivity distributions without being affected by offset errors. We have also developed an inversion algorithm to simultaneously recover multidimensional distributions of resistivity and magnetic susceptibility from various types of loop-loop EM data. This development of a new algorithm was motivated by the fact that EM data are often affected by both resistivity and magnetic susceptibility particularly where metal objects are buried. For these inversion methods to work successfully, the data must be collected at multiple heights and/or different loop configurations.