Sinkholes in the city of Hamburg—New urban shear-wave reflection seismic system enables high-resolution imaging of subrosion structures

Krawczyk, Charlotte M.; Polom, Ulrich; Trabs, Stefan; Dahm, Torsten

doi:10.1016/j.jappgeo.2011.02.003

Cited by 87 publications

(89 citation statements)

References 43 publications

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“…As seismic source we used the electrodynamic vibrator system ELVIS (Polom et al, 2011;Krawczyk et al, 2012). We reached a depth of 300 m with P-waves and about 50 m with S-waves.…”

Section: Geophysical Methodsmentioning

confidence: 99%

Numerical modelling of climate change impacts on freshwater lenses on the North Sea Island of Borkum using hydrological and geophysical methods

Sulzbacher

Wiederhold

Siemon

et al. 2012

Hydrol. Earth Syst. Sci.

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Abstract.A numerical, density dependent groundwater model is set up for the North Sea Island of Borkum to estimate climate change impacts on coastal aquifers and especially the situation of barrier islands in the Wadden Sea. The database includes information from boreholes, a seismic survey, a helicopter-borne electromagnetic (HEM) survey, monitoring of the freshwater-saltwater boundary by vertical electrode chains in two boreholes, measurements of groundwater table, pumping and slug tests, as well as water samples. Based on a statistical analysis of borehole columns, seismic sections and HEM, a hydrogeological model is set up. The groundwater model is developed using the finite-element programme FEFLOW. The density dependent groundwater model is calibrated on the basis of hydraulic, hydrological and geophysical data, in particular spatial HEM and local monitoring data. Verification runs with the calibrated model show good agreement between measured and computed hydraulic heads. A good agreement is also obtained between measured and computed density or total dissolved solids data for both the entire freshwater lens on a large scale and in the area of the well fields on a small scale.For simulating future changes in this coastal groundwater system until the end of the current century, we use the climate scenario A2, specified by the Intergovernmental Panel on Climate Change and, in particular, the data for the German North Sea coast. Simulation runs show proceeding salinisation with time beneath the well fields of the two waterworks Waterdelle and Ostland.The modelling study shows that the spreading of well fields is an appropriate protection measure against excessive salinisation of the water supply until the end of the current century.

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“…As seismic source we used the electrodynamic vibrator system ELVIS (Polom et al, 2011;Krawczyk et al, 2012). We reached a depth of 300 m with P-waves and about 50 m with S-waves.…”

Section: Geophysical Methodsmentioning

confidence: 99%

Numerical modelling of climate change impacts on freshwater lenses on the North Sea Island of Borkum using hydrological and geophysical methods

Sulzbacher

Wiederhold

Siemon

et al. 2012

Hydrol. Earth Syst. Sci.

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“…LIAG's hydraulically driven vibrator systems MHV2.7 and HVP-30 (Buness and Wiederhold, 1999) were used as seismic sources for Pwave surveys and MHV4S (Polom et al, 2010) for S-wave surveys. For VSP measurements the small electro-dynamical vibrator system ELVIS Krawczyk et al, 2011) was used as a seismic source. Adequately chosen acquisition parameters (Table 1) as well as thorough processing provide good structural images of the subsurface.…”

Section: Seismic Methodsmentioning

confidence: 99%

“…Lesmes and Friedman, 2005;Pride, 2005). These considerations should contribute to improved rock identification based on seismic and resistivity results.…”

Section: T Burschil Et Al: Compiling Geophysical and Geological Infmentioning

confidence: 99%

Compiling geophysical and geological information into a 3-D model of the glacially-affected island of Föhr

Burschil

Scheer

Kirsch

et al. 2012

Hydrol. Earth Syst. Sci.

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Abstract. Within the scope of climatic change and associated sea level rise, coastal aquifers are endangered and are becoming more a focus of research to ensure the future water supply in coastal areas. For groundwater modelling a good understanding of the geological/hydrogeological situation and the aquifer behavior is necessary. In preparation of groundwater modelling and assessment of climate change impacts on coastal water resources, we setup a geological/hydrogeological model for the North Sea Island of Föhr.Data from different geophysical methods applied from the air, the surface and in boreholes contribute to the 3-D model, e.g. airborne electromagnetics (SkyTEM) for spatial mapping the resistivity of the entire island, seismic reflections for detailed cross-sections in the groundwater catchment area, and geophysical borehole logging for calibration of these measurements. An iterative and integrated evaluation of the results from the different geophysical methods contributes to reliable data as input for the 3-D model covering the whole island and not just the well fields.The complex subsurface structure of the island is revealed. The local waterworks use a freshwater body embedded in saline groundwater. Several glaciations reordered the youngest Tertiary and Quaternary sediments by glaciotectonic thrust faulting, as well as incision and refill of glacial valleys. Both subsurface structures have a strong impact on the distribution of freshwater-bearing aquifers. A digital geological 3-D model reproduces the hydrogeological structure of the island as a base for a groundwater model. In the course of the data interpretation, we deliver a basis for rock identification.We demonstrate that geophysical investigation provide petrophysical parameters and improve the understanding of the subsurface and the groundwater system. The main benefit of our work is that the successful combination of electromagnetic, seismic and borehole data reveals the complex geology of a glacially-affected island. A sound understanding of the subsurface structure and the compilation of a 3-D model is imperative and the basis for a groundwater flow model to predict climate change effects on future water resources.

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“…The survey set-up is designed for near-surface reflection-seismic profiling, especially in urban areas, e.g. the suppression of surface Love waves if the first subsurface layer is of higher seismic velocity than the second layer, which is often the case on paved or compacted roads (Polom et al, 2010;Krawczyk et al, 2012). For a successful survey in a karst area the use of a high-frequency signal and a dense receiver and source spacing are important for detecting the strong lateral and vertical, structural variations induced by dissolution and obtaining high-resolution images of the subsurface (Wadas et al, 2016).…”

Section: Shear Wave Datamentioning

confidence: 99%

“…30 m below surface due to a relatively poor resolution, but for instance shear waves (S wave) are able to image the near-surface in high resolution (Dobecki and Upchurch, 2006;Krawczyk et al, 2012;Polom et al, 2016b;Wadas et al, 2016). Interpretation of near-surface faults and structures from the surface down to ca.…”

Section: Introductionmentioning

confidence: 99%

Structural analysis of S-wave seismics around an urban sinkhole: evidence of enhanced dissolution in a strike-slip fault zone

Wadas¹,

Tanner²,

Polom³

et al. 2017

Nat. Hazards Earth Syst. Sci.

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Abstract. In November 2010, a large sinkhole opened up in the urban area of Schmalkalden, Germany. To determine the key factors which benefited the development of this collapse structure and therefore the dissolution, we carried out several shear-wave reflection-seismic profiles around the sinkhole. In the seismic sections we see evidence of the Mesozoic tectonic movement in the form of a NW-SE striking, dextral strike-slip fault, known as the Heßleser Fault, which faulted and fractured the subsurface below the town. The strike-slip faulting created a zone of small blocks ( <100 m in size), around which steep-dipping normal faults, reverse faults and a dense fracture network serve as fluid pathways for the artesian-confined groundwater. The faults also acted as barriers for horizontal groundwater flow perpendicular to the fault planes. Instead groundwater flows along the faults which serve as conduits and forms cavities in the Permian deposits below ca. 60 m depth. Mass movements and the resulting cavities lead to the formation of sinkholes and dissolutioninduced depressions. Since the processes are still ongoing, the occurrence of a new sinkhole cannot be ruled out. This case study demonstrates how S-wave seismics can characterize a sinkhole and, together with geological information, can be used to study the processes that result in sinkhole formation, such as a near-surface fault zone located in soluble rocks. The more complex the fault geometry and interaction between faults, the more prone an area is to sinkhole occurrence.

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Sinkholes in the city of Hamburg—New urban shear-wave reflection seismic system enables high-resolution imaging of subrosion structures

Cited by 87 publications

References 43 publications

Numerical modelling of climate change impacts on freshwater lenses on the North Sea Island of Borkum using hydrological and geophysical methods

Numerical modelling of climate change impacts on freshwater lenses on the North Sea Island of Borkum using hydrological and geophysical methods

Compiling geophysical and geological information into a 3-D model of the glacially-affected island of Föhr

Structural analysis of S-wave seismics around an urban sinkhole: evidence of enhanced dissolution in a strike-slip fault zone

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