Details of the abstract
Title of paper  Application of the skew parameters in 1D and 2D inversion of MT data 
List of authors  Yakovlev, D., Koryagin, K., Epishkin, D., Zorin, N., Yakovlev, A. 
Affiliation(s) 
STC NordWest, Lomonosov Moscow State University 
Summary 
1D and 2D magnetotelluric (MT) inversion is often used in practice. However, some MT data used in such inversions may show 3D behavior in a certain frequency range, and the question is how these effects should be accounted for. The idea we present here is to increase the confidence intervals for the data within the frequency range, where they correspond to a higherdimensional media, proportionally to the values of the observed skew (inhomogeneity) parameters. For example, the following criteria may be used to prepare MT curves for 1D inversion. For amplitude data the values N, Skew_S and Skew_B are used. These parameters are dimensionless and range from 0 to 1, indicating deviation of the medium from 1D (N) and 2D (Skew_S, Skew_B) models. Then the modified confidence intervals ΔlgZ for the amplitude curves may be calculated as: ΔlgZ= ΔlgZ_original+N+Skew_S+Skew_B. For phase data, the phase tensor parameters Δφ and β are used. These parameters are measured in degrees and also indicate deviation of the medium from 1D (Δφ) and 2D (β) models. Accordingly, the modified confidence intervals for the phase curves Δarg(Z) may be defined as: Δarg(Z)= Δarg(Z)_original+Δφ+β. The MT curves prepared in this way during inversion will make it possible to fit data more accurate in those frequency ranges where the dimension of the medium corresponds to the dimension of the inversion used. This technology is implemented in the Inversio program, which is designed for analysis and 1D/2D inversion of large amount of MT data. At the analysis stage the interpreter, looking at the frequency sections of the skew parameters, decides which of the parameters to use to penalize the curves. The simplicity of the technology makes it very convenient in largescale MT projects with a variable geological structure of the environment. 
Session Keyword  2.0 Theory, Modelling and Inversion 
File upload 
2.0_application_of_the_skew_p_yakovlev.pdf
