Electrical Resistivity Imaging

Electrical Resistivity Imaging is a geophysical technique for imaging subsurface structures using electrical measurements.

By measuring the electrical properties of the subsurface a profile of the strata width, depths and thicknesses can be produced. This is done by placing regularly spaced electrodes into the ground along a straight line. By collecting parallel lines of data a 3D map of the subsurface strata can be produced.

The depth attainable depends on the number and spacing of electrodes, with an average line of 64 electrodes spaced at 2m apart, (126m in total) a depth of over 12m can be achieved.

As can be seen in the example below, a change in topography along the line has a large influence on the data, so each line is accurately surveyed.

As well as mapping out bedrock depths and other layers, resistivity imaging is often used as a monitoring tool alongside our surface and building monitoring. Whilst monitoring any movement at the surface, the pseudo sections provide information about where the movement originates.

By overlapping continuous lines routes for new pipelines, roads, etc can be surveyed quickly and economically with up to 750m covered in a day.

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