Short-term velocity variations of three rock glaciers and their relationship with meteorological conditions

Abstract

Abstract. In recent years, strong variations in the speed of rock glaciers have been detected, raising questions about their stability in a changed climate. In this study, we present continuous time series over three years of surface velocities of six GPS stations located on three rock glaciers in Switzerland. Intra-annual velocity variations are analyzed in relation to local meteorological factors, such as precipitation, snow(melt), as well as air and ground surface temperatures. A main focus of this study lies on the abrupt velocity peaks, which have been detected at two steep and fast moving rock glacier tongues. The continuous measurements with high temporal resolution revealed that all rock glaciers experience clear intra-annual variations in movement where the timing and the amplitude is rather similar between individual years. The seasonal decrease in velocity was typically smooth, starting one to three months after the seasonal decrease in temperatures, and was stronger in years with colder temperatures in mid winter. The seasonal acceleration always started during the zero curtain period, often was abrupt and rapid compared to the winter deceleration, and at two stations it was interrupted by short velocity peaks, occurring immediately after high water input from snowmelt or heavy precipitation. The findings of this study suggest that both, the seasonal acceleration and the short velocity peaks are strongly influenced by water infiltration, causing thermal advection and increase in pore water pressure, and that likely no velocity peak was solely caused by high temperatures. In contrast, the amount of deceleration in winter seems to be mainly controlled by winter temperatures.

Rainfall as primary driver of discharge and solute export from rock glaciers: The Col d'Olen Rock Glacier in the NW Italian Alps

“…Keeping in mind that the flow of the rock-glacier water into the pond is localised and sub-surficial, it is possible that part of the flow path is in fine-grain sediments and in bedrock fractures (Colombo et al, 2018b), thus further increasing the residence time of water in the system. The observed residence times are similar to the delay detected between events of strong precipitation and peaks in rock-glacier movement (Wirz et al, 2016).…”

Kinematics and geomorphological changes of a destabilising rock glacier captured from close-range sensing techniques (Tsarmine rock glacier, Western Swiss Alps)

“…Rapid acceleration and longitudinal extension develop surface disturbances (e.g., cracks, crevasses and scarps) as signs of the so-called landform destabilization (Delaloye et al, 2013;Marcer et al, 2019;Vivero and Lambiel, 2019;Marcer et al, 2020;RGIK, 2022). In this context, the main factors of rock glacier acceleration and destabilization have been attributed to permafrost degradation due to increased atmospheric warming (Roer et al, 2005;Roer et al, 2008;Deline et al, 2015;Bodin et al, 2017), and by related feedback mechanisms such as increasing water content (Ikeda et al, 2008;Wirz et al, 2016;Buchli et al, 2018;Cicoira et al, 2019). Likewise, mechanical overload caused by rockfall deposits (Delaloye et al, 2013;Scotti et al, 2017) or artificial overload by mining waste deposits (Valenzuela, 2004) have also been identified as triggers of rock glacier destabilization.…”

“…Rock glacier kinematics have been traditionally measured by ground surveying techniques such as theodolite or total station instruments (Francou and Reynaud, 1992;Koning and Smith, 1999), differential GPS (Berthling et al, 1998), differential realtime kinematic (RTK) GPS (Lambiel and Delaloye, 2004) and permanent GPS stations (Wirz et al, 2016;Buchli et al, 2018). Nevertheless, remote sensing techniques such as aerial photogrammetry (Groh and Blöthe, 2019), high-resolution optical satellite imagery (Necsoiu et al, 2016;Blöthe et al, 2021), satellite radar interferometry (InSAR, Rignot et al, 2002;Strozzi et al, 2020) and airborne laser scanning (ALS, Bollmann et al, 2015) have become more broadly employed in recent years, mainly due to their ability to monitor vast and remote regions.…”

Detection and Analysis of Ground Deformation in Permafrost Environments

“…Recent developments include miniaturisation and automation with smaller and less power-consuming receivers operating autonomously and transmitting their raw data or processed positions, possibly in real time, through terrestrial or satellite links. This development is increasingly combined with advances in network technology, so that sets of GNSS and other sensors can optimise measurements and transfer of data (Wirz et al, 2015(Wirz et al, , 2016. The traditional differences between geodetic dual-frequency instruments (millimetre accuracy), which are expensive and power-consuming, and cheaper and less power-consuming single-frequency receivers (metre accuracy) is becoming smaller (centimetre to decimetre accuracy) by using the carrier phase in addition to the GNSS code-information, analysing relative deformation within a network of multiple receivers, and applying advanced temporal filtering techniques.…”