Investigating characteristics of magnetotelluric responses according to magnetotelluricobserved data using 3-D numerical modelling*
Xiong Bin 1, Luo Tian-Ya♦1, Chen Long-Wei 1, Dai Shi-Kun2, Xu Zhi-Feng 1, Li Chang-Wei 1, Ding Yan-Li 1, Wang Hong-Hua 1,and Li Jing-He 1
1. College of Earth Sciences, Guilin University of Technology, Guilin 541006, China.
2. School of Geosciences and Info-Physics, Central South University, Changsha 410083, China.
Abstract：
Fully recognize various problems in the observed magnetotelluric (MT) data is the precondition of inverse solutions. In the paper, according to the geomorphological conditions of the observational MT stations in the Guangxi area, we constructed several diff erent kinds of models to conduct a three-dimensional forward simulation of the MT fi eld using the vector finite element method (FEM). First, the variation rule and diff erences of apparent resistivity ρxy and ρyx in the xy and yx modes were studied and analyzed, and then the geoelectric information reflected by the change of apparent resistivity ρxx and ρyy were discussed. Final, the responses of typical geological structures that cause a static shift problem were presented. The synthetic examples showed that ρxy and ρyx were relevant to the layout of the survey line, for instance, ρxy had diff erent values along the west-east profile compared with that of the southnorth profi le, Moreover, ρxx and ρyy could subtly show the abnormal body-host rock interface, which could be used to restrict the anomalous domain in the inversion process. Moreover, the static shift can be related not only to the size and buried depth of the underground anomalous body, but also to the surface rivers and hills, Hence, to reduce the influence of static shift on MT data, a reasonable distance between a station and rivers or hills should be considered in accordance with the scale of rivers or hills.
. Investigating characteristics of magnetotelluric responses according to magnetotelluricobserved data using 3-D numerical modelling*[J]. APPLIED GEOPHYSICS, 2020, 17(4): 601-615.
2020, Vol. 17 
