Sinkhole and Cave ERI

 ERI image of sinkhole and cave system confirmed by drilling

Fig. 1. 260 ft long ERI profile over karst features confirmed by observation. Profile was collected with 28 electrodes spaced by 2 m and used a dipole-dipole array. Penetration is ~35 ft. Air-filled cave has high resistivity (red).  Mud-filled sink holes have low resistivity (blues). Courtesy of Schnabel Engineering.