P- And S-Wave Seismic Imaging of Sinkhole Structures in the City Of Hamburg
S. Tschache, U. Polom, H. Buness and C.M. Krawczyk
Event name: 24th European Meeting of Environmental and Engineering Geophysics
Session: Geophysics in Engineering Geology and Geotechnical C & Investigations - Slope Instabilities and Tunnel Investigations A & Investigations - High-resolution Engineering Seismic Studies A
Publication date: 09 September 2018
Info: Extended abstract, PDF ( 3.14Mb )
Price: € 20
Sinkholes pose a natural hazard, especially in densely populated areas. In Hamburg-Groß Flottbek, two slowly subsiding sinkholes are known that lie above a salt diapir flank. The Wobbe See sinkhole is a collapse structure that has been buried and built up. The Flottbek Markt sinkhole is a suffosion sinkhole. We applied P-wave and S-wave reflection seismics on coinciding profiles to study the structure of the sinkholes and their causes. Additionally, a pseudo 3D P-wave dataset was acquired. The P-wave and S-wave seismic sections show mostly a good accordance. S-waves enable a high-resolution imaging of the near-surface. Below the Wobbe See sinkhole, a deepening reflector interrupted by staggered faults can be interpreted, which confirms the outcome of a previous study. Down-bending reflectors and an internal bedding structure are imaged in case of the Flottbek Markt sinkhole. The P-wave data reveal reflections of the salt diapir and caprock due to their higher penetration depth. The results suggest that the combination of P- and S-wave reflection seismics is a suitable tool for the investigation of sinkhole areas, even in urban environments.