Innovative seismic imaging solutions : From hardrock mineral exploration to quick-clay site characterization

Abstract: Seismic methods are an efficient and powerful tool to explore the subsurface. It principally helps to gain information on the subsurface structure, bedrock topography, and the nature of the host rock. This thesis showcases two sites in Sweden, where their geological setting, rock structure and geological environment are different, but seismic still shows its potential in soil investigation.The first case application was in Blötberget mine, where there is an iron-oxide deposit of high-quality. It was tested the validity of an electromagnetic vibrator (E-Vib) as a seismic source for a hardrock environment, and applied a tailored processing workflow to the seismic data to image the iron-oxide deposit.The second case study was in Lilla Edet city, where there is the presence of quick-clays in the region. From this seismic dataset, it was retrieved a S-wave reflection section from a vertical-impact source recorded on vertical-component. In the same study area, it was also imaged the P-P and S-S wavefield reflections from a 9C dataset. This provided insight on the benefit of 9C seismic data acquisition for quick-clay landslide studies.Findings of this work prove that the E-Vib test at the Blötberget mine (Sweden) validated its effectiveness and quality for the hardrock environment. The broadband source combined with a tailored processing workflow allowed imaging of the iron-oxide deposits in improved resolution compared to the earlier seismic data. The seismic dataset in the second case study, especially the S-wavefield reflections, presented detailed information on the structures and physical conditions of the sediments. P-wavefield seismic sections in quick-clay environments proved useful to locate the bedrock level and layering above it, but with low resolution. However, S-wavefield seismic section presented more advantages for this geological setting presenting higher resolution images.