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EMIX 34 PLUS - EM Conductivity Modeling & Electromangetic Processing Software
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General

EMIX 34Plus is designed for the interpretation of EM conductivity data acquired with the Geonics Ltd. EM31, EM34, or EM 38 instruments. Forward and Inverse modeling is done on individual sounding stations and the results are displayed in profile form. The results are in terms of apparent condictivity response.

EMIX 34Plus computes the forward model using the full solution described by H.P. Patra and K. Mallick in Geosounding Principles, 2 (1980) published by Elsevier. The inversion calculation uses the Inman-style ridge regression approach of nonlinear least squares curve fitting. Geometric soundings using the vertical magnetic dipole (VMD) or horizontal magnetic dipole (HMD) or both modes are supported either in terms of change in coil separation-frequency or instrument height.

EMIX 34Plus interprets and presents data acquired as a profile. Profiles can differ with respect to frequency, coil height and spacing, in the horizontal coplanar or vertical coplanar coil configurations. You may use different instruments, or the same instrument in different configurations, or both methods to collect data. The use of multiple combinations produces data sets interpretable as soundings.

EMIX 34Plus lets you divide the profile data into five segments along the profile and then fix the individual model parameters for each segment. This allows flexibility in integrating known geologic or geophysical information into the interpretation.

Layered Interpretation allows the user to interpret sounding data at each station in terms of a model with up to five plane layers. Results are in terms of apparent conductivity response for each configuration of frequency, spacing and coil height. This data is presented as apparent conductivity at low induction number, although the forward calculations account for the deviation from the low induction number assumption. The quadrature response of the earth is converted to apparent conductivity using eq. (2) from McNeill (Geonics Limited Technical Note TN-6. 1980) The in phase component of the field is ignored.

EMIX 34Plus features the interactive graphics interpretation mode; you move from station to station along the profile establishing the starting forward model. You can invert the sounding at this time if you choose. Inverse modeling allows the user to obtain a model that best fits the data in a least squares sense. This is done using ridge regression to adjust the parameters of a starting model in an iterative manner.

You may constrain some of the parameters of the layered starting model so that they will not be adjusted by the inversion. Layers are fixed across sections of the model, not on a point by point basis. Starting models can have up to 5 layers; the maximum number of fixed segments is 5.

Inverse modeling of layered models can be carried out in batch mode. Accurate results are achieved even if the low induction number assumption is not satisfied.

EMIX 34Plus provides a data logger interface to data files created by the Geonics Ltd. data logger and an ASCII interface using the Geosoft XYZ format.

Standard Components

EMIX 34Plus software and manual.