Glaciogenic Periglacial Landform in the Making : Geomorphological Evolution of a Rockfall on a Small Glacier in the Horlachtal, Stubai Alps, Austria

• Published in: Remote Sensing
• Main Authors: Fleischer, Fabian, Haas, Florian, Altmann, Moritz, Rom, Jakob, Ressl, Camillo, Becht, Michael
• Format: Article in Journal/Newspaper
• Language: German; English
• Published: MDPI 2023
• Subjects: Ice; permafrost
• Online Access: https://edoc.ku.de/id/eprint/31726/; https://doi.org/10.3390/rs15061472; https://edoc.ku.de/id/eprint/31726/1/2023_fleischer_remote_sensing.pdf

Deglaciation in high mountain areas signifies the transition from glacial to periglacial conditioned landscapes. Due to the reduced melt rate of debris-covered glacier ice, these areas of the glacier may persist long after the surrounding glacier has melted, resulting in the formation of distinct post-glacial landforms. In this study, we examine the geomorphological evolution and potential future development of a 19,267 m3 ± 204 m3 rockfall from the permafrost-affected headwall on the low-elevated Zwieselbachferner in the Horlachtal, Stubai Alps, Austria. The analysis uses multi-epochal remote sensing data, including photogrammetrically and airborne laser scanning-derived digital elevation models, orthophotos, and satellite data, covering a period from the initial rockfall in 2003/2004 to 2022. The data reveals that the rockfall event resulted in the formation of a supraglacial debris layer of varying thickness, spanning an area of 15,920 m2. Subsequently, 13 further rockfalls ranging from 67 m3 ± 6 m3 to 4250 m3 ± 121 m3 were detected. The mean ice thickness of the debris-covered area only slightly decreased between 2006 and 2022, in contrast to the surrounding glacier, whose thickness and length have strongly decreased. This results in the formation of a steep front and flanks that become increasingly covered by debris redistribution. The study suggests that the glacier ice covered by rockfall-derived debris will remain as a periglacial landform of glacial origin after the complete melting of the surrounding glacier.