HR: 1330h
AN: NS23A-01    [Abstracts]
TI: Simultaneous Inversion of Resistivity and Magnetic Permeability from MT Data
AU: * Cao, J
EM: caojx@cdut.edu.cn
AF: Chendu University of Technology, Erxianqiao Dongsanlu No.1, Chengdu, 610059 China
AU: Li, X
EM: lixm@cdut.edu.cn
AF: Chendu University of Technology, Erxianqiao Dongsanlu No.1, Chengdu, 610059 China
AU: He, Z
EM: hzh@cdut.edu.cn
AF: Chendu University of Technology, Erxianqiao Dongsanlu No.1, Chengdu, 610059 China
AB: MT ( Magnetotellurics Method ) is one of most important geophysical prospecting methods. Traditionally, MT data inversion is carried out based on the supposition that the rocks are of magnetic permeability equaling to that of free-space. However, lava and other a few rocks often have higher magnetic permeability than that in free-space. It has been proved that the rocks with a relative magnetic permeability of large than 1.005 may cause remarkable effect on the magnetotellurics responses. We proved, by forward modeling, that the pseudo-resistivity may increase by 5 ohm when the relative magnetic permeability is large than 1.01. There are a few rocks, including lava, that are often of a relative magnetic permeability of larger than 1.01. So, if we do MT investigation in the area where there are rocks with higher magnetic permeability, we should take the magnetic parameter into account in the MT inversion, i.e. we should carry out. simultaneous inversion on resistivity and magnetic permeability. Based on Randall Mackie's MT inversion strategy, we develop a new MT data inversion method that reconstructs the resistivity and magnetic permeability simultaneously. Cases study showed that the new inversion strategy could improve the precision of the resistivity image reconstructed and supply magnetic feature information of the rocks, which, in the case study, is very important for the determinative judgement to be carry out. Simultaneous inversion of MT data for resistivity and magnetic permeability is a difficulty non-linear inverse problem. There are a few factors that may affect the image reconstruction, and there is room in our inversion program to be improved. The work was supported by NSFC under grant No.40274019 and 49894190.
DE: 0600 ELECTROMAGNETICS
DE: 3260 Inverse theory
SC: Near-Surface Geophysics [NS]
MN: 2005 Joint Assembly