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Edi2Mare

Edi2Mare is a little GUI to help you to convert EDI-files into the correct format to run inversions with MARE2DEM. Its development has been sponsored by GEOTEM Ingeniería S.A. de C.V. (http://geotem.com.mx) in Mexico City, and it has been released to the public under the GNU General Public License V3. So far it has only been used with files created with ProcMT and with WinGLink.

  • MARE2DEM is a parallel adaptive finite element code for 2D forward and inverse modeling for electromagnetic geophysics. It was developed with funding support from the Scripps Seafloor Electromagnetic Methods Consortium, http://mare2dem.ucsd.edu.
  • ProcMT is free and open-source software to process MT data, provided by Metronix Geophysics, http://geo-metronix.de.
  • WinGLink is a multidisciplinary software program developed to process, interpret and integrate several geophysical disciplines in a unique interpretation model, developed by Schlumberger http://www.slb.com.

Some warnings:

  1. Edi2Mare was programmed in the Linux-version of Matlab R2012b. It was not tested outside this environment (not with other versions of Matlab nor on Windows/Mac).
  2. Edi2Mare was created to solve a problem. However, there is lots of room for improvements. If you find Edi2Mare useful, and have the time to improve the code, then please go ahead!
  3. Edi2Mare was only tested with *.edi-files from ProcMT, and *.wln-files from WinGLink.
  4. There are apparently different possible formats for *.wln-files. At the moment, only two are supported. 4 header lines are expected for both, and the frequency values must be in the first column. Then, Rho XY, Phi XY, Rho YX, and Phi YX are expected either in columns {2, 3, 4, 5} or in columns {3, 5, 7, 9}. In the first case, the file must have less than 9 columns. This part is fragile. If you have an issue with loading *.wln-files, have a look at the file GUI/load_data.m from line 230 onwards.

Summary

With Edi2Mare you can:

  • Prepare *.edi-files for Mamba2D and MARE2DEM; Edi2Mare will create the file *.emdata, which can subsequently be loaded with Mamba2D.
  • Correct for Static Shift by using TEM-data; automatic estimation is possible.
  • You can use *.wln-files, exported from WinGLink, instead of *.edi-files.
  • Adjust the altitude of the receivers, Z-shift (MARE2DEM requires that all receivers are in the subsurface).
  • Define the inversion-line (0-point and angle) and select the receivers for this line.
  • Select the frequency-band that goes into the inversion.
  • Deselect bad data.
  • Define error levels.
  • Show Robert L. Parkers D+ approximation.

User interface

Example screenshot: Image of Yaktocat

I believe that Edi2Mare is simple enough so it does not require lots of information. A few notes:

  • Installation:

    • Just copy the whole repo to your computer, and add the path to your MATLAB-path.
    • MARE2DEM must be in your Matlab-path.

  • To start Edi2Mare, just execute Edi2Mare in the MATLAB command line.

  • Many elements will show additional information if you hoover over them with your mouse.

  • To start, you have to click on Load in the section Measurement. There you can choose the folder where you have the *.edi- or *.wln-files, and optionally the *.tem-files.

    Important points:

    1. In the data-folder you need a file coordinates.txt. The format of this file is:

      Name Easting Northing Altitude

      For instance:

      10_MT-1 749570.000 2224523.000 1620.125
      11_MT-2 747507.000 2223857.000 1565.855
      12_MT-3 745604.000 2224368.000 1526.000
      13_MT-Test 755432.000 2222445.000 1795.514

    2. The names of the *.edi-, *.wln-, and *.tem-files and the names of coordinates.txt have to start with the same 2-digit number, for instance:

      • 13_mt_auto_processing_median.edi

      • 13_NETEM.tem

      • coordinates.txt

        13_MT-Test 755432.000 2222445.000 1795.514

      The part following the number (##_) in the names of coordinates.txt is used to name the receivers; in the example the used name for that receiver would be MT-Test. These names and the file-names may not contain spaces.

  • Z-Shift is positive facing downwards (convention from MARE2DEM).

  • The automatic Fit for the Static Shift is just a suggestion, not necessarily the best values; it is a minimization between MT and TEM data.

  • North and East are given in kilometers in Edi2Mare.

  • The angle of the inversion-line is counterclockwise, in degrees.

  • The System is for instance 14 N; the UTM Coordinate System.

  • The errors are in %.

Edi2Mare with data exported from WinGLink

The idea of Edi2Mare was to create the file *.emdata for MARE2DEM from *.edi-files created with ProcMT. If you have MT data in WinGLink, there is a possibility to use them for Edi2Mare too. You have to export the MT data as *.wln-files: Open the data in WinGLink => Soundings, and then Files => Edit data ... => File => Export to File... and save them with the ending .wln. (Exporting *.edi-files does not work, because then you would export the original file, without the changes you made in WinGLink.)

The functionality of Edi2Mare is limited if you use *.wln-files instead of *.edi-files. You only see Apparent Resistivity and Phase, no Impedances. D+ does not work either. However, it still works to create the *.emdata-file and subsequently run an inversion with MARE2DEM.