Imaging of Subsurface Structures by AEM Surveys in Korea

Airborne EM method has been used to locate best area for detailed ground geophysical surveys in Korea since 2013. To account for the Korean geologic condition and tough topography, small and light-weight AEM system was selected. GREATEM system can get greatest depth of investigation (DOI) using ground electric source, while SkyRay system carries relatively small transmitting loop compared commercial ATEM system, which serves as a general purpose mid-depth survey tool. As an extension of GREATEM system, Drone-GREATEM system uses drone or multi-copter to carry small coil and provides an effective way of AEM survey in a small area. These three systems are integrated to form a concept of three-fold AEM configuration, which provides options depending on the requested DOI, areal coverage and spatial resolution. In the field data examples, GREATEM survey was successfully applied to locate graphitic phyllite formation for uranium exploration and SkyRay system could locate lead-zinc mineralized zone. Drone-GREATEM provided reasonable results in the site investigation at a railway tunnel construction site. Thus, we could have an efficient and cost effective way for mineral exploration and geologic investigation using airborne EM method.