Continuous real-time slope monitoring of the Ingelsberg in Bad Hofgastein, Austria

The Ingelsberg in Bad Hofgastein, Austria, is a highly hazardous mountain slope in the State of Salzburg. The Ingelsberg exhibits periodic episodes of instability, prompting major efforts to construct rock fall retention basins and safety nets to mitigate risks associated with future slope failures. As the results of traditional slope monitoring have proved rather ambiguous, continuous real-time monitoring of the Ingelsberg was performed from March 2013 through July 2014. The monitoring was undertaken with a Ground Based Interferometric Synthetic Aperture Radar (GB-InSAR). The data set of approximately 130, 000 radar scans represent the first long-term GB-InSAR measurements made in Austria, and indicate an episodic pseudo-sheeting failure process, somewhat analogous to the calving of a glacier front. Furthermore, reasonable time of failure predictions for rock fall events having volumes of only several tens of cubic meters could be made from the data set. The GB-InSAR monitoring provides significant insight regarding the overall slope behavior, failure tendencies, and associated geotechnical hazards of the Ingelsberg.