Analysis of Ground Geophysical, Airborne TEM, and Geotechnical Data for Mapping Quick Clays in Sweden

Bastani, Mehrdad; Persson, Lena; Löfroth, Hjördis; Smith, Colby A.; Schälin, David

doi:10.1007/978-3-319-56487-6_41

Cited by 6 publications

(3 citation statements)

References 9 publications

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“…Quick clay was identified above the coarse-grained layer during visual inspections of the core samples of boreholes BH1 to BH3 (Salas-Romero et al, 2016). Figure 6a-e show the seismic results for line 5-5b, their interpretation, the earlier P-wave refraction tomography and RMT (Wang et al, 2016), and ATEM resistivity results (Bastani et al, 2017). Figure 6b also includes the natural gamma radiation and magnetic susceptibility data from borehole BH3 (distance to the line 0.23 m; Salas-Romero et al, 2016) and the total sounding data from borehole 7062 (distance to the line 90.3 m; BGA, 2018).…”

Section: Reflection Seismic Processingmentioning

confidence: 86%

“…The thin dashed white line indicates the depth above which the results are considered of higher confidence. (e) ATEM resistivity results (Bastani et al, 2017) superimposed on the interpreted seismic section.…”

Section: Reflection Seismic Processingmentioning

confidence: 99%

“…The detailed objectives are (i) 3-D geological-geophysical modelling of the larger-scale subsurface structures overlying and existing within bedrock-like possible fracture zones, (ii) understanding the role of an identified coarse-grained layer and its spatial relationship with the bedrock surface that may improve the hazard assessment, (iii) hydrological modelling of the groundwater within the coarse-grained layer to better understand the development of quick clays in the study area, and (iv) investigating the riverbanks of the Göta River, its bed, and mass-movement deposits. Reflection seismic (both legacy and new sets of seismic profiles acquired within this study), P-wave refraction tomography (mainly from Wang et al, 2016, but for the new profiles performed in this study), and airborne transient electromagnetic (ATEM) and radio magnetotelluric (RMT) resistivity models (Bastani et al, 2017;Wang et al, 2016) are correlated with borehole data (Branschens Geotekniska Arkiv - BGA, 2018;Salas-Romero et al, 2016) for the identification of different types of clays, coarse-grained materials, and bedrock. Using the interpreted seismic sections together with total sounding (BGA, 2018) and high-resolution lidar data (©Lantmäteriet), elevation surfaces from the top of the bedrock and the top and bottom of the coarse-grained layer are modelled.…”

Section: Introductionmentioning

confidence: 99%

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Subsurface characterization of a quick-clay vulnerable area using near-surface geophysics and hydrological modelling

et al. 2019

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Abstract. Quick-clay landslides are common geohazards in Nordic countries and Canada. The presence of potential quick clays is confirmed using geotechnical investigations, but near-surface geophysical methods, such as seismic and resistivity surveys, can also help identify coarse-grained materials associated with the development of quick clays. We present the results of reflection seismic investigations on land and in part of the Göta River in Sweden, along which many quick-clay landslide scars exist. This is the first time that such a large-scale reflection seismic investigation has been carried out to study the subsurface structures associated with quick-clay landslides. The results also show a reasonable correlation with radio magnetotelluric and travel-time tomography models of the subsurface. Other ground geophysical data, such as high magnetic values, suggest a positive correlation with an increased thickness of the coarse-grained layer and shallower depths to the top of the bedrock and the top of the coarse-grained layer. The morphology of the river bottom and riverbanks, e.g. subaquatic landslide deposits, is shown by side-scan sonar and bathymetric data. Undulating bedrock, covered by subhorizontal sedimentary glacial and postglacial deposits, is clearly revealed. An extensive coarse-grained layer (P-wave velocity mostly between 1500 and 2500 m s−1 and resistivity from approximately 80 to 100 Ωm) exists within the sediments and is interpreted and modelled in a regional context. Several fracture zones are identified within the bedrock. Hydrological modelling of the coarse-grained layer confirms its potential for transporting fresh water infiltrated in fractures and nearby outcrops located in the central part of the study area. The modelled groundwater flow in this layer promotes the leaching of marine salts from the overlying clays by seasonal inflow–outflow cycles and/or diffusion, which contributes to the formation of potential quick clays.

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Section: Reflection Seismic Processingmentioning

confidence: 86%

Section: Reflection Seismic Processingmentioning

confidence: 99%