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Quick-clay Landslides in Sweden - Insights from Shear-wave Reflection Seismics and Geotechnical Integration
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, Near Surface Geoscience 2013 - 19th EAGE European Meeting of Environmental and Engineering Geophysics, Sep 2013, cp-354-00029
- ISBN: 978-90-73834-38-5
Abstract
As part of a joint project studying clay-related landslides in Nordic countries, we successfully tested the use of high-resolution shear-wave reflection seismics to survey shallow structures that are known to be related to quick-clay landslide processes. Three 2-D reflection seismic profiles were recorded in Frastad, southern Sweden, above the main slide area, using a 120 m long streamer of 120 SH-geophones at 1 m spacing, and the ELVIS micro-vibrator as source (10 s long sweep ranging from 20 to 160 Hz). The longest profile along a gravel road shows clear internal structuring of the up to 50 m thick marine sediments as well as strong undulations of top basement underneath. Different sedimentary sequences can be distinguished, and the quick-clay sequence is interpreted in 15-20 m depth, which correlates well with the height of the most recent scarp. The shear-wave velocities suggest extremely low values of 100-120 m/s, which geotechnically prohibits building areas. In addition, test measurements on a stubble field parallel to the gravel road showed the first time that the suppression of Love waves is not only restricted to paved surfaces. In addition, the gap between structural data from ground-penetrating radar and P-wave seismics can be closed.