A simple ERT example

The upper blue area shows the rectangular domain used for this ERT survey. The red rectangle is a low resistivity anomaly (an underground tank or buried waste), which we are trying to detect, only by making measurements around the edge of the domain. The red U-shaped source symbol which moves around the outside of the domain indicates where the source is located, during each portion of the tomographic survey.

Each frame in the animation represents an entire electrical resistivity survey, which is a fixed DC current source and a set of voltage measurements made along the edge of the domain (the small aqua triangles).

The plot at the bottom shows the results of inverting the resistivity data collected in the surveys, with each new source location (and set of voltage measurements with it) the inverted picture of the anomaly becomes clearer.

The inversion results show that, each additional survey adds more "understanding" to the overall picture of where, and what shape the anomaly is, but after many surveys have been performed, there is a diminishing return on the improvement in the image.

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