Two-dimensional Inversion of Magnetotelluric Sounding Data
Chen Leshou, Cai Gang, Ma Tao, 1989. "Two-dimensional Inversion of Magnetotelluric Sounding Data", An Overview of Exploration Geophysics in China — 1988, Zhao Jingxiang, Wang Yanjun, Fu Xuexin, Stanley H. Ward
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The two-dimensional (2-D) inversion method of magnetotelluric (MT) sounding data described involves: (1) Constructing initial models for 2-D inversion based on qualitative analysis of MT data and formalized one-dimensional quantitative interpretation; (2) Computing at high speed the MT response function and its partial derivatives with respect to the model parameters for the iterative inversion by means of a primary data base and three-variable cubic-spline interpolation; and (3) Conducting 2-D inversion using the modified method of generalized inverse matrix. The general expression of three-variable cubic spline interpolation was derived by formally extending the univariate-cubic spline interpolation. The computing procedure for the spline function, as well as the construction of the primary data base is described. The generalized inverse matrix method which we modified has distinguishing features and has proven more effective than conventionally used methods. After applying this modified method to an MT profile in the north Jizhong (Central Hebei) depression, we present 2-D inversion interpretation taking into account some available geological and geophysical information. 2-D forward modeling was later performed through cut-and-trial method to reduce the fitting error; as a result the detailed structures have been outlined.