Specifications

University of Pretoria etd – Combrinck, M (2006)
The plates show very similar responses compared to that of the infinite layer. The main
differences are that the depths would be underestimated slightly for the smaller plates if the
same criteria are used as for the infinite layer and that the finite plates cause “lower than
background” imaged conductivity anomalies after the peak values, reaching negative values
in the high contrast cases. This behaviour is due to a reduction in cumulative conductance
values and not a reduction in depth as was found for high contrast boundaries. It is
therefore important to distinguish between the reasons causing negative imaged
conductivities as these contain important information on the subsurface conductivity
structure.
4.5.3.6 Conductive prisms in a half space
The effect of thicknesses in the same order as horizontal dimensions is investigated in this
section. The same sizes and conductivities are used as for the horizontal plates. Results
for the low contrast models are shown in Figures 4-52 to 4-54.
1
10
100
0 100 200 300 400 500 600
Depth [m]
Cumulative Conductance [S]
100 m X 100 m X 100 m
200 m X 200 m X 200 m
300 m X 300 m X 300 m
400 m X 400 m X 400 m
Figure 4-52: Cumulative conductance for a 0.2 S/m prism at 150 m depth in a 0.02 S/m host
rock. The prism dimensions vary from 100 m to 400 m.
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