Integrated Geophysical Methods Applied to Sinkhole Problems in North Germany

Sinkholes are holes at the surface due to the collapse of the bedrock in the subsurface. The working area proposed for this study is located north of Hamburg, in Schleswig-Holstein, around the town of Münsterdorf, which is 3 km to the south of Itzehoe. Here sinkholes occurred in 2004, 2006 and 2007 at three places in the south-western part of the town, near a football field.

Seismic (both P- and S-wave) reflection, in combination with resistivity surveys have been conducted to the southwest of the town near to the observed sinkholes with the aims:

• to detect faults, fracture zones, and karst features that may have caused the formation of the linearly-aligned sinkholes at the surface,
• to determine the depth to the carbonate layers and salt domes, and

• to analyse the lateral and vertical position of leachable horizons that lead to the sinkhole collapse.

In particular, a seismic reflection survey was conducted in September 2007 with a P-wave vibroseis source along three profiles to detect deeper fault zones that may related to the salt dome known as Krempe-Lägerdorf. After the occurrence of a third sinkhole in November 2007, a high resolution S-wave vibroseis survey and several boreholes were added. We observe some discontinuities in the reflection of top of the Upper Cretaceous layer, but there is no vertical fault displacement of the horizontally-stratified rock beds.