Does array type matter?

Click the buttons below to see the array sketch (top), data (middle) and inversion models (bottom) for four different survey array types over a synthetic model.

Pole-pole array
Dipole-dipole array
Pole-dipole left array
Pole-dipole right array

Evidently all surveys generate interpretable models, and geology interpreted from those models will likely be very similar. The differences are due to the changes in how current flows in the ground. Zones with higher current densities will be more reliably imaged. To analyze this issue a little more carefully you could generate second models for each situation and create images with depth of investigation properly characterized.

Conventional wisdom is that of these arrays, the pole-pole tends to illuminate more of the ground (to greater depths) but it has the lowest spatial resolution. It is also the most inexpensive to conduct in the field if survey lines are long and the survey area is rough. The dipole-dipole arrays have the highest resolution, shallowest depth of investigation, and are more expensive to run because four electrodes need moving instead of only two. The pole-dipole surveys are a compromise, which used to be harder to interpret, owing to assymetry of pseudosections, but now inversion procedures remove this problem.