Comparing Automatic and Manual Methods for Determination of the Bedrock Interface Using AEM Data

Abstract

An extensive airborne electromagnetic (AEM) survey was carried out in Norway with the primary purpose to obtain information of depth to bedrock in areas with little or no prior geotechnical knowledge. We present different approaches to extract a bedrock model from the high-resolution time-domain AEM data, including both automated and manual procedures. It is found that in the area of investigation a user-driven approach of manual bedrock picking is most suitable, taking into account the strongest vertical resistivity gradient and geological information as additional information. A semi-automatic, statistical method, called Localized Smart Interpretation (LSI), is presented and discussed in addition. This method, while not included in the original bedrock model for the entire area, proved promising and should thus be implemented in future projects of similar scope.