EMIX 34 PLUS  EM
Conductivity Modeling & Electromangetic Processing
Software
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 Inmanstyle 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 separationfrequency 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 TN6. 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.
