The Characteristic States of the Magnetotelluric Impedance Tensor: Construction, Analytic Properties and Utility in the Analysis of General Earth Conductivity Distributions

摘要: It is shown that the Magnetotelluric (MT) impedance tensor admits an anti-symmetric generalized eigenvalue - eigenstate decomposition consistent with anti-symmetry of electric and magnetic fields referred to same coordinate frame: this achieved by anti-diagonalization through rotation 2x2 complex operators SU(2) group. The eigenstates comprise simple proportional relationships between linearly polarized eigenvalues input output field along locally resistive conductive propagation path into Earth, respectively mediated maximum minimum characteristic values (eigen-impedances). from first principles eigen-impedances are expected be positive real (passive) functions, analytic in entire lower-half frequency plane singularities confined on imaginary axis. Insofar as generated isometric transformation eigen-impedances, it also passive. passivity effective means appraising measured tensors for compliance basic tenets MT method: can violated only presence sources Earth. In addition extrinsic effects (e.g. noise), demonstrated examples, such may secondary large or small scale inductive phenomena realistic conductivity configurations. However, they not time-independent taking place a passive induction context, steady-state current channelling, galvanic distortion reversals. general, assert whether violation has occurred, necessary decompose tensor, refer its intrinsic frame evaluate their properties