Abstract
The quantification of rock glacier kinematics on a regional basis has gained increasing importance in recent years. Here, we applied an image tracking approach on high-resolution aerial imagery to infer surface kinematics of 129 mapped rock glaciers in the Kaunertal, Austrian Alps. We find significant surface movement for 30 features with mean velocities falling between 0.11 and 0.29 m yr−1 and a maximum of 1.7 m yr−1. Local analysis and comparison to earlier studies reveals significant increases in rock glacier velocities in the study area. From the rock glacier inventory and high-resolution digital topography, we computed a series of morphometric parameters to analyze potential controls on rock glacier creep and to predict rock glacier activity using random forests and logistic regression models. The results point towards a stronger dependence of velocities on parameters describing general inclination, potentially acting as proxies for internal rock glacier properties, while activity states seem to be regulated mainly by rock glacier dimensions and topoclimate. Using a parameter subset, we successfully separated active from inactive rock glaciers with accuracies of up to 77.5%, indicating a promising approach to predict rock glacier activity solely relying on parameters that can be derived from regionally available data sets.
Highlights
Rock glaciers are globally prevalent features of creeping permafrost in the periglacial zones of high-latitude and high-altitude environments
We successfully separated active from inactive rock glaciers with accuracies of up to 77.5%, indicating a promising approach to predict rock glacier activity solely relying on parameters that can be derived from regionally available data sets
Our results reveal significant surface movement for 30 of these rock glaciers throughout the observation period that were classified as active (Figure 3 and Figure S1)
Summary
Rock glaciers are globally prevalent features of creeping permafrost in the periglacial zones of high-latitude and high-altitude environments. Rock glaciers are described as lobate or tongue-shaped landforms containing composites of ice-rich sediments that move downslope in a creeping behavior under the effects of gravitational deformation [1]. Berthling (2011) [5] defines active rock glaciers concisely as the “visible expression of cumulative deformation by long-term creep of ice-debris mixtures under permafrost conditions” [5]. In spite of the difficulties presented in finding a consistent definition of rock glaciers, their occurrence has been observed and documented globally in various high-latitude and high-altitude locations [2,3,6,7,8]
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