Since 2008, the centre of the city has reported to have risen some , after initially sinking a few millimeters. This has caused considerable damage to buildings in the city centre, including the historical town hall. The cause for this geological change has been identified as a drilling operation conducted in the summer and autumn of 2007 to provide
geothermal heating to the city hall. The drilling perforated an
anhydrite layer and caused high-pressure
groundwater to come into contact with the anhydrite, which then began to expand. By 2010, some sections of town had risen by . In July 2013, no end to the rising process was in sight. Data from the
TerraSAR-X radar satellite before and after the changes have confirmed the localised nature of the situation. "A geochemical process called
anhydrite swelling has been confirmed as the cause of these uplifts. This is a transformation of the mineral anhydrite (anhydrous calcium sulphate) into
gypsum (hydrous calcium sulphate). A pre-condition for this transformation is that the anhydrite is in contact with water, which is then stored in its crystalline structure". ==Infrastructure==