Distortion in MT data take place due to either galvanic effect, induction effect or mixing of them. Static shift is a subset of galvanic distortion which moves MT curve upwards or downward. Static shift is frequency dependent term while the induction depends on frequency.
Hello,
Static shifts are usually caused by resistivity in-homogeneities close to the electric dipoles of the MT soundings and arise basically from two phenomena:
a) electric field distortion due to the dependency of the electric field on the resistivity of the material where the voltage difference is measured and
b) current distortion (current channelling or repelling).
these two phenomena are independent of the frequency of the current.
But at very high frequencies Eddy currents may be induced and they are frequency dependent. And so, in this case, the static shift can also be frequency dependent.
I hope it helped you.
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