Using Geophysics to Locate Underground Caves and Voids

Caves, sinkholes and other karst features generally have very different electrical conductivity properties than the surrounding limestone bedrock.  Caves and caverns that are filled with air are highly resistive relative to limestone; water-filled caverns are highly conductive relative to limestone; and buried sinkholes filled with clay are also highly conductive relative to limestone.  Geophysical survey of potential construction sites in limestone terrain is an effective tool to locate these and other karst features that pose engineering challenges.