Our studies have determined that both gradient and dipole-dipole arrays may produce a rather strong electromagnetic (EM) coupling effect under certain conditions. Variations in these apparent effects are closely correlated with changes of surface current density and also influenced by topographic relief. The dipole-dipole array can provide EM coupling anomalies with the same sign and shape as bona fide induced-polarization (IP) anomalies.It has been shown by theoretical calculations and model studies that response curves of frequency effects of EM coupling in logarithmic coordinates have distinctive features of sectional linearization. This can provide a basic method to correct approximately EM coupling. Compared with methods being used inside and outside China, the suggested correction method has the advantage of wide application. This has been already proven by a few field examples.

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