Open AccessEnhanced resolution for long electrode ERT
Author(s) -
Rucker Dale F.
Publication year - 2012
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.2012.05643.x
Subject(s) - superposition principle , offset (computer science) , electrode array , resistive touchscreen , outlier , electrical conductor , computer science , algorithm , inverse problem , electrode , physics , mathematics , artificial intelligence , electrical engineering , mathematical analysis , computer vision , engineering , quantum mechanics , programming language
SUMMARY The resolution of the long electrode electrical resistivity tomography method is investigated through the comparison of arrays. The investigations included a synthetic model study and a pilot‐scale field experiment, in which data from the 2‐pole and 4‐pole arrays were used to reconstruct known targets through inverse modelling. The results confirmed that the 2‐pole array maps conductive targets with low lateral resolution and no vertical resolution. The 4‐pole array performs extremely well or extremely poorly depending on the specific subset of data used in the inversion modelling. The worst performance was observed from using a randomized 4‐pole subset. In this case, the reconstructed target was offset from the known location. The best performance came from evaluating the comprehensive data set comprising all possible 4‐pole combinations and choosing favourable subsets that minimized outliers in transfer resistance, geometric factor, data error and apparent resistivity. These favourable 4‐pole subsets were capable of resolving both conductive and resistive targets with higher fidelity than the 2‐pole array. Unfortunately, it may not be possible to acquire the comprehensive 4‐pole data set, especially for a large number of electrodes. A viable alternative is to acquire the comprehensive 2‐pole data set and calculate any desired 4‐pole subset using superposition. In this way, the geophysicist will also have full advantage of signal strength and shorter measurement cycle that accompanies the 2‐pole array.