1-D inversion of resistivity and induced polarization data

Francisco J. Esparza Hernández and Enrique Gómez-Treviño
fesparz@cicese.mx & egomez@cicese.mx

In this site you can invert 1-D apparent resistivity data by internet. The server is located in http://geoinversion.cicese.mx, but you can be in any place in the world, all what you need is a internet connection and a set of Schlumberger apparent resistivity data. This data are in the input file, see the first line of the internet page. The algorithm used to invert the data is based on a Linear Programming solution to Gomez Trevino's nonlinear equations, see related papers for more information on the algorithm. In addition you can invert also Induced Polarization data (IP). The input file is organized as follows, see sample input file for an actual example.

  1. Num. of data, Num. of unknowns, log10 of the multiplicative factor for the apparent resistivity data (usually 0).
  2. AB/2 apparent resistivity uncertainty in app. resistivity.
  3. Depth discretization. The first value must be the thickness of the first layer, then must be greater than zero. The next values are the depths of the next layers, the number of 'z' values to be read are Num. of unknowns less one.

The output files are 'model' and 'resps'. In 'model' the first column is 'z' and the second column is 'log10(rho)'. The third column of the file 'resps' contains the response of the final model. The output files for IP are organized in a similar fashion to DC, but the second column of 'modip' is chargeability.

Good luck with the code, Shoud you have any questions don't hesitate to contact me at fesparz@cicese.mx.

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Applied Geophysics Department
Earth Science Division
CICESE, México