AN APPROACH TO THE INVERSION OF THE MAGNETOTELLURIC DATA OF THE INHOMOGENEOUS MEDIUM
Sun Chuanwen(Institute of Geology,State Seismological Bureau,Beijing 100029)Wang Guange Chen Leshou(China University of Geosciences,Beijing 100083)
Significant errors may result when applying one dimensional (1-D) interpretation methods to magnetotelluric (MT) data collected in two dimensional (2-D) or three dimensional (3-D).Both resistivities and depths can be grossly incorrect if 1-D methods are applied in a 2-D or 3-D setting.Many methods to solve the existing problems can not be used practically beause of its computertime consumming and high costs and its strict application conditions.I suggest that the better methods can avoid complicated calculation such as finite elements,difference,integral equation etc.On the basis of the abstract to the 2-D or 3-D responses in the layered earth and the principles of fuzzy mathematics,I have developed a new method which has many advantages over exsisting ones:(1)It is able to eliminate 2-D or 3-D inhomogeneity effects and give a good and accurate 1-D geoelectric section.(2)It takes only a few minutes to complete an inversion on IBM/XT,so it can be easily applied to.practical work.However other methods spend about a few days inversing one 2-D geoelectric section's MT data on IBM/XT.(3)It is able to take into acount the both polarizations (TE and TM) at the same time,also inverse them respectively.The results can be verified by each other.(4)It has less problems of multiple solutions than other methods when processing MT data.