Full-tensor magnetic gradiometry: Comparison with scalar total magnetic intensity, processing and visualization guidelines

Abstract

Full-tensor magnetic gradiometry data have been collected commercially for the last few years. However, to date, there is still no clarity on how to compare these data to scalar total field surveys. Some users display the vertical gradient of the vertical component (B_zz) and compare that to a first vertical derivative of total field with the caveat that ‘they are similar’. Others compute the length of the measured vector and call that total field. We establish the basic formulas to calculate total field from the tensor components and demonstrate this with a real data example from Thompson, Manitoba, Canada. Another key question is whether full-tensor interpolation is required to obtain total field from tensor data. We compare the results from using a commercial full-tensor interpolation algorithm with standard minimum curvature of the tensor components individually and with another open-source code that uses a radial basis function interpolator on the individual tensor components. All three applications produced a total field grid of superior quality to that calculated from a scalar total field survey available for the area of study.