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P- And S-Wave Seismic Imaging of Sinkhole Structures in the City Of Hamburg
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 24th European Meeting of Environmental and Engineering Geophysics, Sep 2018, Volume 2018, p.1 - 5
Abstract
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.