A multi-methodical approach based on GBInSAR, Satellite InSAR, and terrestrial Laserscanning for the investigation and monitoring of an unstable rock slope

In the year 2019, at Kartais (Hüttschlag, Austria) parts of an approximately 100 m high and fractured rock wall mainly composed of calcareous-mica-schists became unstable and collapsed two times. The first failure event was a wedge failure and occurred on the 25th of March 2019 and released about 3.000 m³ of rock material. Blocks with a maximum volume of about 100 m³ were falling, bouncing and sliding to the valley bottom, but did not reach the Großarl River and the local infrastructure (road, bicycle track and houses). The second failure event happened on the 15th of July 2019 involving a volume of about 5.000 m³ with a maximum block size of 200 m³. This event had a longer runout but also did not reach the infrastructure. A Helicopter-based observation by the Geological Survey of Salzburg has shown that new cracks at the top of the failure area have already opened to apertures in the scale of decimetres to metres. It is assumed that the newly formed potential failure mass could reach 10.000 m³ and thus is even larger than the two previous events. In order to study the deformation behaviour of the rock face a multi-methodical observation and monitoring campaign has been initiated recently. A UAV-photogrammetry survey has shown that the foliation of the calcareous-mica-schist is dipping moderately into the slope and the rock wall is dissected by at least 4 different joint sets, whereas two of them intersect to form wedge failures. Since November 2019 a GBInSAR system (LisaLab) is continuously monitoring the slope. Additionally, multi-temporal terrestrial laserscanning (TLS) surveys and satellite based InSAR analysis were performed.

In this contribution, the set-up of the investigation and monitoring campaign as well as some preliminary results will be presented.