The Study Of The Magnetotelluric Probability Tomography Method

MT probability tomography method is a new geophysical inversion method. Based the basic principle of the accumulation of induced electric charges across the resistivity discontinuities and the induction current channeling inside the conductive bodies inspirited by the MT field, we set up the relation between the measured field on the earth surface and the distribution of the induced source underground by means of the defining the electric charge occurrence probability function and the electric dipole occurrence probability function and the spacial distributing of the 'correlation probability' .The 'image' of the field sources underground, or the distributing graphy of the induced electric charges and the induced current in the mesuring area can be drawed, from which we can get the outline of the geological anomaly on the meaning of the probability.The probability in the probability tomography method is defined with the degree of correlation or fitting in this paper. The methods of the definitions of the scan functions and the occurrence probability functions, the electric field under the TM model and the magnetic field under the TE model, are given respectively. We also have brought forward the correlation probability tomography method of magnetotelluric field-derivative and the waveform function-fitting probability tomography method, and have analysed and tested these methods in the way of the selection of the setting field and the capability of noise-standing, etc with synthetic models. The theory is also tested by some practical applications in this paper.Anslysing theoretically the mechanism of the probability tomography method, we have summed up the basic theory of the probability tomography, whose physical reliability is tested on large numbers of synthetic and practiced by data processing of CSAMT.