As shown in Figure 1, this surface-borehole survey was configured using the ZZ Universal resistivity meter to accurately locate known caves for structural reasons. The operator collected 60k data points in only one hour.

This survey is aimed at finding voids for construction safety purposes, as the figure below shows, 32 and 20 electrodes were placed into two boreholes, respectively. The inversion image found that the low resistivity areas beside the boreholes were likely to be karst caves. Later site investigati...