Remarkable urban uplift in Staufen im Breisgau, Germany: Observations from terraSAR-X InSAR and leveling from 2008 to 2011

Abstract

As geothermal energy is of increasing importance as a renewable energy source, there is a high demand for comprehensive studies to prevent failure during implementation, as is the case in Staufen im Breisgau, Germany. The drilling of seven wells for the geothermal heating of the city hall in 2007 is thought to have disturbed the existing hydro-geological system in the complex structured transition zone of the Upper Rhine Graben and the Schwarzwald massif. This event has led to uplift, related to the transformation of anhydrite to gypsum, which affects the infrastructure of the city centre via the generation of large cracks. This study focuses on the application of the InSAR Small Baseline Subset (SBAS) approach using 50 X-band radar images from the German TerraSAR-X satellite (TSX) to map the spatial and temporal patterns of the deformation field in detail. X-band InSAR time series analysis for the three-year time period from July 2008 through May 2011 indicates maximum velocities of ~12 cm/yr in the line of sight (LOS) direction, from the ground to the satellite, approximately 50 m northeast of the drilling field. In comparison with leveling data for the same time period, TSX data analysis better delineates the border of the deformation area, and it is able to map the amount of deformation associated with different parts of the city. Moreover, this comparison indicates contributions of horizontal motion, as is expected for uplift patterns. © 2013 by the authors.