Acquisition, Processing and Interpretation of Geophysical Data from the Fen Complex in Telemark, Norway

Abstract

This Master s thesis focuses on the acquisition and processing of geophysical data to map the geology of the Fen Complex in Telemark, Norway. Three resistivity and two seismic profiles where acquired at the Fen Complex during September and October of 2016. The refraction seismic has been processed using traditional techniques, such as Hagedoorn s method, and tomographic inversion using the Rayfract® software. The results from both processing methods have been compared to investigate which method creates the most accurate image of the subsurface. The resistivity has been processed using the RES2DINV software.

The tomographic inversion has been run using different parameters, and a recommendation of the best settings for this study is presented. The results of the resistivity measurements and seismic surveys have been compared to each other and correlated to data from boreholes in close proximity to investigate soil characteristics, depth to bedrock, possible fracture zones and to create a geological interpretation of the area.

The correlation between the depth to bedrock interpreted from the seismic and the resistivity measurements is concluded to be good. As a result, the resistivity measurements can be used to infer the depth to the bedrock. Multiple low velocity zones have been mapped along the seismic profiles and a geological interpretation is presented. The soil characteristics of the area have multiple interpretations. Therefore, further geotechnical investigation is necessary to make a conclusive characterization.