A computer implemented method, for use in multi-string corrosion monitoring, comprising: obtaining electromagnetic (EM) log measurements of a well having at least one inner tubing string and at least one outer tubing string, the measurements including first channel measurements for higher resolution from a first sensor array , and second channel measurements for deeper penetration from a second sensor array ; inverting the first channel measurements data over a characterization region of the well and the second channel measurements data over the characterization region of the well in order to obtain: an attribute of the at least one outer tubing string based on a second plurality of calibration coefficients, wherein the second plurality of calibration coefficients are based on a comparison of the second channel measurements with second channel model predictions; and an attribute of the at least one inner tubing string based on a first plurality of calibration coefficients and the second plurality of calibration coefficients, wherein the first plurality of calibration coefficients are based on a comparison of the first channel measurements and first channel model predictions; and storing the attribute of the at least one outer tubing string and the attribute of the at least one inner tubing string as a function of position along the well . obtaining electromagnetic (EM) log measurements of a well having at least one inner tubing string and at least one outer tubing string, the measurements including first channel measurements for higher resolution from a first sensor array , and second channel measurements for deeper penetration from a second sensor array ; inverting the first channel measurements data over a characterization region of the well and the second channel measurements data over the characterization region of the well in order to obtain: an attribute of the at least one outer tubing string based on a second plurality of calibration coefficients, wherein the second plurality of calibration coefficients are based on a comparison of the second channel measurements with second channel model predictions; and an attribute of the at least one inner tubing string based on a first plurality of calibration coefficients and the second plurality of calibration coefficients, wherein the first plurality of calibration coefficients are based on a comparison of the first channel measurements and first channel model predictions; and an attribute of the at least one outer tubing string based on a second plurality of calibration coefficients, wherein the second plurality of calibration coefficients are based on a comparison of the second channel measurements with second channel model predictions; and an attribute of the at least one inner tubing string based on a first plurality of calibration coefficients and the second plurality of calibration coefficients, wherein the first plurality of calibration coefficients are based on a comparison of the first channel measurements and first channel model predictions; and storing the attribute of the at least one outer tubing string and the attribute of the at least one inner tubing string as a function of position along the well . <EOS>