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Simultaneous Inversion of Resistivity Structure and Electrode Locations in ERT
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, Near Surface Geoscience 2014 - 20th European Meeting of Environmental and Engineering Geophysics, Sep 2014, Volume 2014, p.1 - 5
Abstract
Accurate coordinates of electrodes are essential in ERT, and electrode mislocation or inaccurate information on electrode positions inescapably results in crucial distortions of the subsurface images. This problem would be more probable in crosshole ERT due to lack of borehole deviation data or to their inaccuracy. ERT monitoring especially performed in an area where ground deformations are expected such as in landslide monitoring may also suffer from this problem owing to the electrode movements over time. To provide a fundamental way to solve these problems, a new inversion algorithm was developed so that resistivity distribution and electrode coordinates are simultaneously optimized. We performed numerical experiments to examine the performance of the developed algorithm. The numerical experiments showed that x coordinates can be recovered close to the true ones while the inverted z coordinates have higher errors. Even though the true coordinates cannot be precisely calculated, we were able to calculate the distribution of resistivity which was comparable to the inversion results based on the true electrode coordinates. Finally, the performance of the proposed algorithm is highlighted in two field applications: a surface ERT survey at a landslide-prone are and a crosshole ERT survey.