Geotechnical ground investigations with a small airborne TEM prototype system

In this paper we show how time domain electromagnetic data from a small airborne prototype system was successfully used for geotechnical ground investigations at a road construction site in Central Norway. The measured data were processed and inverted with time efficient semi-automatic processing tools. Subsequently, the resistivity models recovered by AEM data inversion were automatically interpreted with machine learning based algorithms that were trained with geotechnical drilling data. Both the thickness of a sediment layer overlaying bedrock and the type of sediment was estimated. The measured data and the inverted resistivity models are compared to those from a regular SkyTEM304 system, which was utilized earlier at the same site. Also, the sediment depth and sediment type estimated from the two AEM datasets were compared, proving the feasibility of such a small airborne TEM system for geotechnical ground of the shallow subsurface.