Development And Application Of Visualization Toolkit For Three-dimensional Magnetotelluric Inversion Based On ModEM

With the great improvement of computer hardware and software and development of three-dimensional inversion theory,the practical application of three-dimensional magnetotelluric inversion algorithm has become a research hotspot.ModEM is a parallel modular inversion system applied to a series of three-dimensional inversion for electromagnetic geophysical data sets,but the system has a lack of auxiliary toolkits,which is not suitable for users.Accordingly,this paper carries out study on development and application of visualization toolkit for three-dimensional magnetotelluric inversion based on ModEM.In this paper,elaboration of the basic principle of three-dimensional NLCG inversion method is carried out.And the basic principles and organizational structure of modular three-dimensional inversion parallel software ModEM based on three-dimensional NLCG inversion algorithm are analyzed,ModEM inversion software consists of general inversion layer,interface layer,numerical discretization layer,mainly to achieve three-dimensional NLCG inversion function for large-scale electromagnetic geophysical data sets.Then the design of toolkit program supporting ModEM inversion software using Python language to prepare,it contains data analysis module,input file module and results mapping module to implement of displaying measuring point distribution map,response parameter mapping,error analysis,input file generation required by ModEM inversion software(data files,initial model files,control files,covariance files),and visual mapping and save function of inversion results in various forms.Moreover,the parameter setting and fileformat are explained and the corresponding examples are given.Finally,the self-developed toolkit was applied to perform three-dimensional inversion of the audio magnetotelluric sounding data sets in the Jiangxi Province Zhentou geothermal field with ModEM inversion software,which revealing the occurrence of tectonic,geothermal resources in the region and the relationship between the different direction of the fracture,and the preliminary evaluation of the geothermal resources in the Zhentou area,which also validates the reliability and practicability of ModEM toolkit.