Factors Controlling Velocity Variations at Short‐Term, Seasonal and Multiyear Time Scales, Ritigraben Rock Glacier, Western Swiss Alps

Abstract

This study analyses the factors controlling variations in short‐term, seasonal and multiyear deformation velocity of an alpine rock glacier from data obtained over periods of 1–20 years. The Ritigraben rock glacier, in the western Swiss Alps, was monitored using tacheometry, terrestrial laser scanning, an in situ global positioning system and borehole deformation measurements. Rock glacier stratigraphy and ground temperature data were obtained from boreholes, and long‐term meteorological data (temperature, precipitation, snow water equivalent) from nearby weather stations. Shearing within a distinct water‐bearing layer represents the major component of the displacement. Short‐term accelerations and seasonal velocity patterns of the rock glacier deformation appear to have been triggered by water supply to this layer. A long‐term acceleration of the rock glacier was probably also caused by increased water supply. Permafrost temperature in the rock glacier has increased slightly since 2002, yet no direct causality could be established between this limited warming and rock glacier acceleration. Copyright © 2017 John Wiley & Sons, Ltd.

Decoupled kinematics of two neighbouring permafrost creeping landforms in the Eastern Italian Alps

“…The two largest deviations in the creeping rates between the MaRG and AmCL occurred in 2009 and in 2012 ( Figure 6a) followed by another smaller deviation in 2014. Several studies (e.g., Delaloye et al, 2008;Kenner et al, 2017) and the results of correlation analyses for the MaRG in this work indicate that increased winter snow accumulation and/or reduced ground freezing during winter are followed by increasing creeping rates on rock glaciers. This probably occurred in the snowy winters of 2009 and 2014 in the Presanella group and more generally in the six years from 2009 to 2014, causing the MaRG acceleration.…”

“…These studies document significant inter‐annual and intra‐seasonal variability in rock glacier displacement rates and suggest that acceleration is mostly triggered by water availability and circulation in and below the permafrost layer (Ikeda et al, ; Kenner et al, ). The role of water in addition to variability in temperature and sediment/ice supply is evidenced by the recent numerical flow modelling of long‐term rock glacier dynamic adjustment to external forcing (Müller et al, ).…”

“…There are detailed investigations and long‐term monitoring programmes for selected rock glaciers, encompassing the last decades, and a summary for the European Alps is reported in Kellerer‐Pirklbauer et al (). These studies combine repeated annual surveys of surface kinematics, continuous ground surface temperature monitoring, geophysical investigations of the internal structure, borehole drillings and monitoring of internal properties such as water content, temperature and displacement along vertical profiles (Kenner et al, ; Buchli et al, ). Recently, the installation of GPS dataloggers has enabled the continuous monitoring of the surface displacement at seasonal or sub‐seasonal resolution, which has been combined with on‐site micro‐meteorological data provided by automatic weather stations (Wirz et al, ).…”

Recent Acceleration of a Rock Glacier Complex, Ádjet, Norway, Documented by 62 Years of Remote Sensing Observations

“…Velocities increase at a decadal scale from ~0.5 to ~3.6 myr −1 from 1954 to 2014, with a recent acceleration from ~4.9 to ~9.8 myr −1 from 2009 to 2016. A comparison between TRI and OT confirms the recent very high velocities but highlights also that the rock glacier complex is affected by seasonal fluctuations normal for rock glaciers (Kenner et al, ; Figure b).…”

Near‐surface ventilation as a key for modeling the thermal regime of coarse blocky rock glaciers

“…with an areal extent of approximately 1.4 km 2 (as of 2012) according to Zenklusen Mutter and Phillips . Thermal data from a borehole drilled in 2002 are available through PERMOS with details of the measurements given in Herz et al Due to a seasonal talik, with water fluxes through the permafrost at a depth of 12–13 m, the cut‐off depth for the model was chosen at 8 m.…”