Abstract: Mohr circles and their application to Magnetotelluric(MT)impedance tensor analysis aredescribed in this paper,It iS illustrated that the rotational invariants of MT impedance tensors,having the advantages of providing variety of MT in a formation and stability,are frequently usedin MT data interpretation,Mohr circle,connecting the different forms of invariant impedancetensors,becomes an important graphic dignostic tool in studying MT impedance tensor properties.With the help of this powerful tool,some MT parameters,such as structural dimensional-ty,skewness,anisotropy,can be expressed visually and simply in the circle diagrams which giveimportant information for studying both vertical and lateral variation of the conductivity structures.

Key words: Magnetotelluric sounding, Impedance tensor, Mohr circle, Conductivity Structure

摘要： 论述了Mohr圆及其在大地电磁阻抗张量分析中的应用。并指出,大地电磁阻抗张量不变量由于提供信息的多样性和稳定性,在应用中具有独特的优点,而Mohr圆又将各种大地电磁阻抗张量不变量有机地联系在一起,使其成为分析研究大地电磁阻抗张量性质的重要图示工具,能直观、清晰、简便地给出构造维数、二维偏离度、各向异性等重要信息,可用来研究测区电性结构沿纵向和横向的变化特征。

关键词: 大地电磁测深, 阻抗张量, Mohr圆, 电性结构特征