130 A new concept of karst development based on hydrogeology and geophysics the OPTV images, which reveal two distinct dark corridors. The convergence of detection through acoustic, electrical, and optical wall imaging methods is noteworthy (Fig. 9). Conclusions The 3D seismic block acquired over the HES revealed three main high-porosity layers—presumably water-bearing—located at depths of 35–40 m, 85–87 m, and 110–115 m. These layers were identified as karstic zones. The presence of these karstic levels was clearly confirmed by both electrical resistivity measurements (Fig. 5) and Optical Televiewer (OPTV) imagery. A comparison between the resistivity panels, long normal resistivity logs, and optical borehole images confirms that the low apparent resistivity anomalies observed in the electrical panels correspond to open, water-filled karst conduits. This correlation is particularly evident in boreholes M07 and M11. Figure 9 Comparison of acoustic, electrical, and optical wall imaging methods in borehole M20. From left to right: the acoustic section, the velocity log, the karstic index log, the electrical resistivity panel, the geological log, the optical wall imagery
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