Channelling contribution to tipper vectors: a magnetic equivalent to electrical distortion

A novel linear relation between the tipper vector and the impedance tensor has been derived for the long-period approximation. This provides a means of distinguishing current channelling from induction effects on a variety of scales. The method was applied to synthetic and real data from the Canadian shield. The synthetic results support the validity of the method. Application to the real data indicates that, despite the fact that these are more complex than the synthetic data, the method can separate the effects of distortion from those of induction at several scales and complements well the standard impedance tensor analysis.