Further measurments were made between boreholes BK16 and BK18 in a horizontal section. Again a salt solution was pumped through a dipole flow field and tomographic profiles were obtained from the geoelectrical array in the boreholes. The figures below show the resisitvity before injection, after injection and the also the changes in resissivity that occured.

The changes in resisivity therefore represent areas where the salt solution could flow (the fracture network).

Geoelectric Tomograms of the Vertical Section 18/16

Similar measurements were made in a vertical section between boreholes BK 17 and BK 18

Geoelectric Tomograms of the Vertical Section 17/18

The geoelectric tests provided a non evasive method of examining the existence of fractures with a rock mass. Techniques of this kind may be used in characterisation of a repository for radioactive waste disposal.