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Abstract

Sinkholes are circular to elliptical depression or collapse structures in the Earth’s surface, caused by dissolution and subsurface erosion of soluble rocks such as salt, sulfate and carbonate in the presence of groundwater. Depending on the subsoil structure and generation process, sinkholes may form continuously growing depressions at the surface or collapse abruptly into deep holes with diameters up to several tens of meters. Individual process components may be simple and can easily be understood, but the interaction of different processes ahead of a collapse and precursor phenomena with different rates and dimensions impede full process understanding. The joint project SIMULTAN develops and applies an early recognition system of sinkhole instability, unrest, and collapse, with combining structural, geodetic, geophysical, petrophysical, and hydrogeological mapping methods, accompanied by sensor development, multi-scale monitoring, modelling, and an information platform. Sinkhole-affected areas in Germany are based generally on salt highs (e.g., northern Germany), sulfate karst or carbonate karst (mainly southern Germany). The investigations focus in two areas (Hamburg, Thuringia), for which sinkhole unrest has been identified. While local authorities provide individual information and maps about areas of potential sinkhole hazard, a standardized and collective recognition system does not exist, relevant for especially urbanized areas.