Optimized Arrays for Resistivity Measurements Confined to the Perimeter of a Survey Area
M.H. Loke, P.B. Wilkinson, A. Tejero-Andrade and S. Kruse
Event name: Near Surface Geoscience 2015 - 21st European Meeting of Environmental and Engineering Geophysics
Session: ERT II
Publication date: 06 September 2015
Info: Extended abstract, PDF ( 1.78Mb )
Price: € 20
In some survey problems, particularly in urban areas, the electrodes are confined to the perimeter of the survey area due to physical obstructions. This significantly limits the electrode arrangements that can be used for resistivity survey measurements. Previous methods in designing arrays for such surveys are dependent on the shape of the perimeter, such as rectangles. We use a modification of the 'Compare R' array optimization technique to automatically generate electrode arrays that provide the optimal resolution for perimeters of any shape. The array optimization algorithm is modified by using a weighting function to preferentially select arrays that improve the resolution of structures within the survey perimeter. Plots of the model resolution and point-spread-function help to illustrate the capabilities of the survey technique. It is shown that the vertical resolution is significantly poorer than the horizontal resolution that can be achieved with resistivity surveys. In a synthetic model test with shallow and deep high resistivity blocks in a homogeneous medium, the optimized arrays achieve better resolution of the structures compared to standard arrays designed for a square survey perimeter.