Abstract
ABSTRACTReprocessing of high‐resolution seismic reflection data over groundwater‐bearing glacial deposits near Heby, southeastern Sweden, improved the images of near‐surface structure at this site. Post‐stack time migration and pre‐stack depth migration were tested and compared to determine the improvements on imaging an undulating bedrock surface. The pre‐stack depth migration image displays better continuity of the dipping structures within the glacial sediments and provides a more detailed topography of the bedrock reflector. First‐arrival picks were used to define an initial model for input into tomographic inversion. The tomography result then formed the basis for building the migration velocity model. The final pre‐stack depth migration image shows a strong reflection at around 35 m elevation (about 9 m below the surface) that can be correlated to a thin (0.2 m) hard silt layer. The upper 20 m of overburden is interpreted to consist of clay, and the seismic images show weaker sub‐horizontal reflections within this unit, except for the strong silt reflection, consistent with our modelling results. Below 20 m, sand/gravel sediments are present and overlay the bedrock. Forward modelling based on the pre‐stack depth migration image and subsequent processing shows that pre‐stack depth migration provides a higher resolution image compared with post‐stack time migration. Our study shows that pre‐stack depth migration is preferable to post‐stack time migration even for the shallow near‐surface seismic data acquired at Heby, and that integrating tomography, migration, modelling and geological information provides a better understanding of the structure which these groundwater resources are contained in.
Highlights
Seismic refraction methods and ground penetration tests (e.g. Voyiadjis and Song, 2003; Butler, 2005; Dietrich and Leven, 2006) have been developed for groundwater exploration since the 1940s (e.g. Hasselstrom, 1969; Haeni, 1986)
Near Surface Geophysics published by John Wiley & Sons Ltd on behalf of European Association of Geoscientists and Engineers., Near Surface Geophysics, 1–15
Note that it is not possible to plot common image gathers (CIG) for the post-stack time migration (PSTM) depth-converted image since the data are migrated after stack; we show CIGs for the normal moveout depth-converted data
Summary
Seismic refraction methods and ground penetration tests (e.g. Voyiadjis and Song, 2003; Butler, 2005; Dietrich and Leven, 2006) have been developed for groundwater exploration since the 1940s (e.g. Hasselstrom, 1969; Haeni, 1986). Seismic refraction methods and ground penetration tests The application of seismic reflection methods for shallow hydrogeological problems started in the 1980s Seismic reflection methods may provide higher-resolution im-. Near Surface Geophysics published by John Wiley & Sons Ltd on behalf of European Association of Geoscientists and Engineers. Juhlin of these studies has been to map the top of the groundwater table and the thickness of the groundwater-bearing sediments
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
