The application of electrical resistivity tomography (ERT) for geophysical prospecting is on the increase due to its cost-effectiveness and capabilities of multi-electrode data acquisition. Multi-electrode resistivity systems use protocols that control the transition between the various electrode pairs. Most of these protocols used for a two-dimensional (2-D) electrical resistivity tomography survey assume that the survey lines are straight to ensure collinear electrode pairs. However, due to the presence of surface constraints associated with most of the survey areas, it is seldom possible to conduct resistivity surveys along a straight line. Consequently, uncertainties might creep into the result when such constraint is encountered. This research is aimed to assess the effect of the electrode(s) offline on a 2-D electrical resistivity tomography survey profile. In light of this, Wenner array configuration was adopted for the survey. The data was acquired with all electrodes inline, one offline, two offline, and three offline at stepwise distances, respectively. The qualitative assessment through the resistivity contour plots, revealed slight to distinct variation of anomalies as two or more electrodes are offline at a distance > ½ the minimum electrode spacing (a). The quantitative assessment carried out using Pearson’s correlation coefficient, mean absolute error, and mean absolute percentage error yielded similar results with those obtained qualitatively. Hence, the study has revealed that there is a significant effect on the 2-D resistivity model when two or more electrodes are offline at a distance > ½ a.

由于其成本效益和多电极数据采集能力，电阻率层析成像 (ERT) 在地球物理勘探中的应用正在增加。多电极电阻率系统使用控制各种电极对之间转换的协议。大多数用于二维 (2-D) 电阻率断层扫描调查的协议都假设调查线是直的，以确保共线电极对。然而，由于存在与大多数勘测区域相关的地表限制，几乎不可能沿直线进行电阻率勘测。因此，当遇到这种约束时，不确定性可能会蔓延到结果中。本研究旨在评估电极离线对二维电阻率断层扫描测量剖面的影响。有鉴于此，本次调查采用温纳阵列配置。数据是在所有电极在线、一个离线、两个离线和三个离线的情况下以步进距离分别获得的。通过电阻率等值线图进行的定性评估显示，由于两个或多个电极离线，距离大于最小电极间距的 ½（一）。使用 Pearson 相关系数、平均绝对误差和平均绝对百分比误差进行的定量评估与定性获得的结果相似。因此，该研究表明，当两个或多个电极以 > ½ a的距离离线时，对二维电阻率模型有显着影响。