Unprecedented Observation of Hourly Rock Glacier Velocity With Ground‐Based SAR

• Published in: Geophysical research letters 2023-05, Vol.50 (9), p.n/a
• Main Authors: Bertone, Aldo, Seppi, Roberto, Callegari, Mattia, Cuozzo, Giovanni, Dematteis, Niccolò, Krainer, Karl, Marin, Carlo, Notarnicola, Claudia, Zucca, Francesco
• Format: Article
• Language: English
• Subjects: Acceleration; Climate change; Glacier velocities; Glaciers; Hourly; Investigations; Kinematics; Landforms; Mountains; Permafrost; Radar; Rhythm; Rock; Rock glaciers; Rocks; SAR (radar); Synthetic aperture radar; Time; Velocity
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2023GL102796

The kinematic acceleration of rock glaciers observed in recent decades shows that the behavior of these landforms is related to climate change. Velocity variations on yearly to seasonal time scales are frequently investigated, but velocity changes measured on shorter time scales (i.e., on hourly resolutions) are as yet poorly investigated. We used a ground based synthetic aperture radar to investigate, on an hourly time scale, the displacement of a rock glacier located in Val Senales (European Alps, northern Italy). We observed velocity fluctuations occurring at a very regular pace, characterized by phases of sharp acceleration (up to 0.9 mm/hr) lasting 4–11 hr followed by long phases of stagnation lasting 13–20 hr. This study describes an unprecedented observation of an hourly velocity rhythm of an active rock glacier and opens up new perspectives in the analysis and interpretation of rock glacier kinematics. Plain Language Summary Rock glaciers are debris landforms commonly found in mountain permafrost environments. Active rock glaciers slowly move downslope, and their kinematics is related to the internal structure and driven by external factors associated with the climatic variables. Rock glacier velocity varies on different time scales, from millennial to annual, and their movement can be observed using a range of techniques. We measured velocity variations of an active rock glacier in the eastern European Alps on an hourly time scale, by using a ground based synthetic aperture radar. For the first time, we documented a peculiar kinematic behavior for a rock glacier, showing a “step‐like” cumulative movement associated with velocity peaks occurring at a regular daily rhythm. The internal processes driving the kinematics of rock glaciers are still not fully understood, and further investigations are needed to clarify the main reasons for the pattern observed in this study. Our unique data provide a new perspective to improve understanding of rock glacier kinematics and their recent velocity acceleration driven by climate change. Key Points We used terrestrial radar interferometry to measure the displacement of an active rock glacier on an hourly time scale We observed velocity peaks lasting 4–11 hr, separated by phases of stagnation lasting 13–20 hr The velocity peaks were observed to have a regular rhythm during the investigated period