Geophysical prospecting for new cave passages: Fort Stanton Cave, New Mexico, USA

Geophysical surveys have been used to predict extensions of newly discovered sections of Fort Stanton Cave, the third-longest cave in New Mexico. Because air-filled caves have almost infinite resistivity, the electrical resistivity (ER) method is a very effective tool for detection of subsurface conduits in the unsaturated zone. Resistivity profiles have been used for several years by local cavers to guide exploration in Fort Stanton Cave. However, the most recent discoveries approach the limits of the depth of investigation of the resistivity equipment used by the cavers. The National Cave and Karst Research Institute has begun conducting resistivity profiles over these deeper portions of the cave system using a SuperSting™ R-8 resistivity meter coupled with longer 112-electrode arrays. These ER tools have been very successful at identifying extensions of known passage in Fort Stanton Cave.