ELECTRIC RESISTIVITY TOMOGRAPHY FOR GEOPHYSICAL INVERSE PROBLEMS

A new method for electric resistivity tomography (ERT) is developed fo r geophysical inverse problems by adapting the sensitivity analysis. T he outputs of the potential electrodes are computed using the two dime nsional finite element method in the wave number space by Fourier tran sforming the governing equations, The resistance distribution in the r egion of interests, which makes the computed potential distribution co incide with the measured potential, is found by minimizing the objecti ve function using an optimization method. In this process the sensitiv ity analysis is introduced in order to compute the derivatives of the objective function. And an adjoint variable method is used to save the computational efforts for sensitivity coefficients.