Anomaly Effects of Arrays for 3d Geoelectrical Resistivity Imaging using Orthogonal or Parallel 2d Profiles
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The effectiveness of using a net of orthogonal or parallel sets of two-dimensional (2D) profiles for threedimensional
(3D) geoelectrical resistivity imaging has been evaluated. A series of 2D apparent
resistivity data were generated over two synthetic models which represent geological or environmental
conditions for a typical weathered profile and waste dump site, respectively, commonly associated with
geophysical applications for hydrogeological, environmental and engineering investigations. Several
minimum electrode separations and inter-line spacing were used to generate the apparent resistivity
data for each electrode array with a view to determining the optimum inter-line spacing relative to the
minimum electrode separation. The 2D apparent resistivity data for each array were collated to 3D data
sets. The effectiveness and efficiency of the arrays in 3D geoelectrical resistivity imaging were
evaluated by determining the mean absolute anomaly effects of the electrodes arrays on the synthetic
models. The anomaly effects observed in dipole-dipole (DDP), pole-dipole (PDP) and Wenner-
Schlumberger (WSC) arrays were generally larger than that observed in other arrays considered. The
least anomaly effect on the synthetic models was observed in pole-pole (PP) array. This indicates that
DDP, PDP and WSC arrays are more sensitive to 3D features. In all the arrays, the anomaly effects
observed in the data set generated using the conventional square grids were slightly larger than those
from parallel or orthogonal 2D profiles. This slight increase is attributed to the increased data density
and is insignificant when compared with those of parallel and orthogonal 2D profiles. Hence, the use of
parallel or orthogonal 2D profiles for 3D geoelectrical resistivity survey is effective.
Keywords
QC Physics