Determining the shape of salt structures using seismic methods

Regions in northern and central Germany where salt structures occur are especially prone to subrosion.The Quickborn region in Schleswig-Holstein is characterised by a rising salt dome that has led to sinkholes and sinkholes in the urban area over the last twenty years. With the measuring system developed at LIAG from a mini-vibrator source (Elvis VII), a growing number of seismic shear wave profiles are being measured and thus courses of the rising salt structure can be determined more precisely; likewise, regions more or less influenced by the salt rise can be distinguished at LIAG. When identifying areas prone to sinkhole formation, sections in which the salt structure occurs in the near-surface area in connection with disrupted or shifted strata are of particular interest, as water pathways can develop at these areas. Borehole logs are employed to support the interpretation of the geological situation.

Gravimetric monitoring network

For several years now, LIAG has operated a gravimetric monitoring network in two regions of Germany – Hamburg Flottbek and Bad Frankenhausen (Thuringia). As the processes are slow and the changes small, the time series must be accordingly long. For the first time, we succeeded in detecting the loss of mass caused by subrosion based on oberservations of temporal changes in Earth’s gravitational field. The monitoring activities have been continued, motivated by these positive results. The examples mentioned above show the focus of our current research in the field of geohazards: improving the imaging of present conditions of the various research objects and establishing new methodological approaches and time series.