Making the Most of Seismic Data for Quick-Clay Landslide Studies

Four seismic lines were acquired in near the Göta river in southwest of Sweden to test capability of ultrahigh-resolution, high-fold, vertical component data for PP- and SS-wavefield retrievals for quickclay landslide studies. The lines, 300–450 m long, were acquired using a 45-kg accelerated drophammer and using 1 m receiver spacing using 10 Hz vertical component geophones. The acquisition was setup so that the wavefield sampling of the shear-waves, because of slow shear-wave velocity (70–100 m/s), would not be aliased in the vertical component data. Results complement each other; however, the shear-wave reflection sections show much greater level of details than the P-waves with a resolution on the order of 1–2 m. Bedrock reflections are imaged as well as internal reflections within the clayey background. Because bedrock was imaged on both P- and S-wavefield sections, it was possible to use this in time for obtaining an average down to bedrock Vp/Vs as a proxy for indicating areas with high water content and possibly prone to quick-clay landslide or liquefaction. Future surveys should consider if even smaller receiver spacing down to 25 cm can be used at one of the test sites for experimental and research purposes.