**12.4 2-D resistivity structure along South-North direction**

The dipole-dipole pseudosections and the 2D resistivity structure along the S-N direction are shown in **Figure 2**. The 2D resistivity structure revealed four geoelectric/ geologic subsurface layers marked A, B, C and D separated by geologic boundaries; namely topsoil marked by A (generally blue colour except at few points with green colour), B (green and blue colour), weathered/fractured basement marked by C (generally green except at few points with yellow colour).The topsoil is generally thin and subsume into the weathered layer in many places due to its thickness and it is characterised mainly by clay but few sandy clay. The weathered layer is characterised by clay and sandy clay, its thickness increases from the centre of the traverse towards the southern and the northern flanks respectively. The northern flank of the weathered layer exhibit very low resistivity values which may be due to high level of saturation and diagnostic effect of wet clay.

The weathered/fractured basement is characterised by two linear features which are between stations 4 and 5(distance at 40 m and 50 m) and stations 14 and 16

**Figure 2.** *2-D modelling of dipole-dipole along S-N direction.*

*Geophysical Investigations for Design Parameters Related to Geotechnical Engineering DOI: http://dx.doi.org/10.5772/intechopen.108712*

(distance at 140 m and 160 m). The upper part of the weathered/fractured basement exhibits lower resistivity than its lower section, signifying that the upper part (green colour) is more weathered than the lower part of the pseudosection.

The depth to bedrock is thinner between stations 7 and 10 (distance at 70 m and 100 m), but increases towards the southern flank (between stations 2 and 7) and increases towards the northern flank(stations 10 and 19), this shows that the bedrock extends beyond the depth of study (30 m) between the stations 2 and 6 and stations 12 and 19. The overburden at the northern flank is characterised by higher portion of clay due to its lower resistivity values when compared with the southern flank.
