Measuring salt mine subsidence

CTM-based subsidence measurements of Südsalz's working salt mine under the historic town of Bad Reichenhall. Nowadays freshwater is used to dissolve salt rocks into brine, which can then be pumped up via wells. The main high subsidence area is within the black rectangle. Südsalz is required by regulators to monitor subsidence at the site and has been doing so since 1988 using terrestrial leveling and Global Positioning System survey methods. Südsalz is interested in CTM and related InSAR technology as a possible means of reducing their monitoring costs. AMEC reviewed 10 years of historically available satellite data, generating 11,000 points of reference and found excellent agreement between the satellite data and the company’s survey findings. The CTM data was found to exhibit extensive coverage and redundancy over urban areas indicating spatially very smooth changes in deformation rates thus providing a high level of confidence in the data as well as insight into the types of deformation occurring.