Description |
ELETOM is Electrical Tomography software that performs the complete 2D inversion of surface electrical surveys with any measurement array (Wenner, dipole-dipole, pole-dipole, pole-pole, user defined arrays, mixed arrays) with a maximum of 64 electrode. It uses the finite element method in two dimensions to model the subsurface electrical response. The elements that define the grid are trapezoidal in form to compensate for any height difference between the electrode positions. The current dispersion in the third spatial dimension (perpendicular to section of interest) is considered by using Wannamaker's correction. It is not necessary to specify any parameter to construct the grid. One needs only to enter the positions and numbering of the electrodes used in the survey's measurements. The iterative algorithm used to perform the inversion is based on the minimisation of the mean square error between field data and the data simulated by the FEM by the method proposed by Sasaki (1994). The algorithm's convergence is obtained by estimating a stabilisation repeated during every iteration. Reduction of noise in the data is obtained with an iterative linear regression calculation (Ward, 1990) that compensates for the fact that it is impossible to know the statistical variance of each measurement. The result is given as a resistivity section reconstructed in two dimensions with a precision equal to the smallest halved inter-electrode distance. A set of colour shadings can be selected to enhance the anomalies. The results can be rendered as isoresistivity curves. Results can be cut and pasted to other programs or exported in Microsoft Word 97 format. The complete user manual is available on-line. Multilingual (Italian, English, French and Spanish). LAN supported. A full working demo version is available on the WWW. |