Static shift of magnetotelluric data and its removal in a sedimentary basin environment

By using a modeling algorithm that derives point voltages rather than point electric fields, this paper considers the effect on the magnetotelluric responses of local near-surface distorting structures, which are both outside of, and inside, the telluric electrode array; shows that static-shift effects are of larger spatial size but of less magnitude than would be expected from conventional modeling. If there exists within the earth a layer whose variation in electrical resistivity along the profile can be treated in a parametric fashion, then static shift of the apparent resistivity curves can be corrected. Deriving the modal value from a sufficient number of observations for the layer resistivity is the most useful approach. -from Author