Combination of 1D laterally constrained inversion and 2D smooth inversion of resistivity data with a priori data from boreholes
R. Wisén, E. Auken and T. Dahlin
Journal name: Near Surface Geophysics
Issue: Vol 3, No 2, May 2005 pp. 71 - 78
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Resistivity imaging in combination with borehole information is a powerful tool for site investigation. We show that the combination of 1D laterally constrained inversion (1D-LCI) with the use of a priori information from borehole data and 2D smooth inversion adds significant value to the interpretation of continuous vertical electrical sounding (CVES) data. The 1D-LCI offers an analysis of the resolution of the model parameters. This is helpful when evaluating the integrity of the model. Furthermore, with the 1D-LCI it is possible to constrain model parameters with a priori information, e.g. depth-to-layer interfaces, based on borehole information. We show that 2D smooth inversion resolves lateral changes well, while 1D-LCI results in well defined horizontal layer interfaces. In geological environments where the lateral variations are not too pronounced, the 1D-LCI contributes to a geological interpretation of the resistivity measurements. Depths to layers can be interpreted with greater certainty than if using results from 2D smooth inversion only. The inclusion of a priori information in the inversion reveals further details and enhances the geological interpretation significantly.