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Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/nhess-2017-315
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
04 Sep 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Natural Hazards and Earth System Sciences (NHESS).
Structural analysis of S-wave seismics around an urban sinkhole; evidence of enhanced subrosion in a strike-slip fault zone
Sonja H. Wadas1, David C. Tanner1, Ulrich Polom1, and Charlotte M. Krawczyk2,3 1Leibniz Institute for Applied Geophysics, Stilleweg 2, D-30655 Hannover, Germany
2GFZ German Research Centre for Geosciences, Telegrafenberg, D-14473 Potsdam, Germany
3Technical University Berlin, Ernst-Reuter-Platz 1, D-10587, Germany
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 subrosion, 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 He├čleser 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 steeply-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 the groundwater is flowing along the faults which serve as conduits. A near-surface fault zone located in soluble rocks can enhance subrosion in two ways: (1) tectonic movements accompanied by strain variations lead to the formation of small fault blocks and a fracture network that increases the rock permeability and creates fluid pathways, and (2) the faults can serve as groundwater conduits. Also note, the more complex the fault geometry and the more interaction between faults, the more fractures are generated and the more prone to sinkholes occurrence is the area.

Citation: Wadas, S. H., Tanner, D. C., Polom, U., and Krawczyk, C. M.: Structural analysis of S-wave seismics around an urban sinkhole; evidence of enhanced subrosion in a strike-slip fault zone, Nat. Hazards Earth Syst. Sci. Discuss., https://doi.org/10.5194/nhess-2017-315, in review, 2017.
Sonja H. Wadas et al.
Sonja H. Wadas et al.
Sonja H. Wadas et al.

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Short summary
In 2010 a sinkhole opened up in the urban area of Schmalkalden, Germany. Shear wave reflection seismic profiles were carried out around the sinkhole to investigate the reasons for the collapse. A strike-slip fault and a fracture network were identified that serve as fluid pathways for water leaching soluble rocks near the surface. The more complex the fault geometry and the more interaction between faults, the more fractures are generated and the more prone to sinkhole occurrence is the area.
In 2010 a sinkhole opened up in the urban area of Schmalkalden, Germany. Shear wave reflection...
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