Evidence of rock slope breathing using ground-based InSAR

Rouyet, Line; Kristensen, Lene; Derron, Marc‐Henri; Michoud, Clément; Blikra, Lars Harald; Jaboyedoff, Michel; Lauknes, Tom Rune

doi:10.1016/j.geomorph.2016.07.005

Cited by 26 publications

(16 citation statements)

References 47 publications

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“…A long-term trend of~2 cm distance and~1 cm height change is observed over our 4 years of monitoring period, where the western slope (AL02) moves upward and inward toward the valley. The magnitude and timing of our measured seasonal bedrock displacements match reversible slope deformations observed in other alpine valleys, thought to be driven by 150-200 m changes in the elevation of the groundwater table (Hansmann et al, 2012;Loew et al, 2007;Rouyet et al, 2017). Our bedrock displacement data thus most likely represent seasonal HM deformation cycles driven by groundwater recharge during snowmelt.…”

Section: Seasonal Bedrock Deformationsupporting

confidence: 74%

“…Reversible slope deformations have been observed in alpine valleys attributed to seasonal groundwater pressure changes (Hansmann et al, 2012;Loew et al, 2007;Rouyet et al, 2017). In an attempt to measure seasonal bedrock deformations associated with groundwater changes close to the glacier margin, as well as any long-term trends associated with ongoing ice retreat (e.g., Bevis et al, 2012), we installed two single-frequency GNSS stations on bedrock on opposite sides of the Great Aletsch Glacier along our Cross-section M (stations AL01 at 1,966 m and AL02 at 1,963 m; Figure 2b).…”

Section: Seasonal Bedrock Deformationmentioning

confidence: 99%

“…Snowmelt and heavy rainfall contribute to surface recharge, temporarily raising the water table (Hansmann et al, 2012), and seasonal groundwater changes can be an important driver of unstable rock slides (Loew, Gischig, et al, 2017;Preisig et al, 2016). Meanwhile, observations in stable alpine valley flanks have highlighted reversible rock slope deformations associated with annual rising and lowering groundwater tables (Hansmann et al, 2012;Loew et al, 2007;Rouyet et al, 2017). Such coupled HM processes may play an important role in driving cyclic fracture propagation over longer time scales (Eberhardt et al, 2016;Preisig et al, 2016), especially in concert with long-term groundwater table fluctuations, for example, associated with changing ice elevation, that alter the affected area over time.…”

Section: Introductionmentioning

confidence: 99%

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Hydromechanical Rock Slope Damage During Late Pleistocene and Holocene Glacial Cycles in an Alpine Valley

et al. 2020

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Subglacial water pressures influence groundwater conditions in proximal alpine valley rock slopes, varying with glacier advance and retreat in parallel with changing ice thickness. Fluctuating groundwater pressures in turn increase or reduce effective joint normal stresses, affecting the yield strength of discontinuities. Here we extend simplified assumptions of glacial debuttressing to investigate how glacier loading cycles together with changing groundwater pressures generate rock slope damage and prepare future slope instabilities. Using hydromechanical coupled numerical models closely based on the Aletsch Glacier valley in Switzerland, we simulate Late Pleistocene and Holocene glacier loading cycles including long‐term and annual groundwater fluctuations. Measurements of transient subglacial water pressures from ice boreholes in the Aletsch Glacier ablation area, as well as continuous monitoring of bedrock deformation from permanent Global Navigation Satellite Systems stations, help verify our model assumptions. While purely mechanical glacier loading cycles create only limited rock slope damage in our models, introducing a fluctuating groundwater table generates substantial new fracturing. Superposed annual groundwater cycles increase predicted damage. The cumulative effects are capable of destabilizing the eastern valley flank of our model in toppling‐mode failure, similar to field observations of active landslide geometry and kinematics. We find that hydromechanical fatigue is most effective acting in combination with long‐term loading and unloading of the slope during glacial cycles. Our results demonstrate that hydromechanical stresses associated with glacial cycles are capable of generating substantial rock slope damage and represent a key preparatory factor for paraglacial slope instabilities.

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Section: Seasonal Bedrock Deformationsupporting

confidence: 74%

Section: Seasonal Bedrock Deformationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hydromechanical Rock Slope Damage During Late Pleistocene and Holocene Glacial Cycles in an Alpine Valley

et al. 2020

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“…They are used to monitor processes at repeat intervals on the order of days to months or years, nevertheless wide spread use as fixed or permanent installation systems has yet to be achieved. At present, Ground-based Interferometric synthetic-aperture radar (GB-InSAR) is widely used for continuous near-real time monitoring of displacements for landslides [10,11], open pit mine walls [12], and rock slopes [13], as it can obtain deformation measurements at the sub-millimeter level and is not affected by weather conditions [14]. For some monitoring applications, however, the use of TLS or SfM may be a feasible alternative to radar monitoring as the system cost can be lower, higher ground resolution can be achieved, volumes can be measured, and 3D displacements can be extracted.…”

Section: Introductionmentioning

confidence: 99%

Development and Optimization of an Automated Fixed-Location Time Lapse Photogrammetric Rock Slope Monitoring System

et al. 2019

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An automated, fixed-location, time lapse camera system was developed as an alternative to monitoring geological processes with lidar or ground-based interferometric synthetic-aperture radar (GB-InSAR). The camera system was designed to detect fragmental rockfalls and pre-failure deformation at rock slopes. It was implemented at a site along interstate I70 near Idaho Springs, Colorado. The camera system consists of five digital single-lens reflex (DSLR) cameras which collect photographs of the rock slope daily and automatically upload them to a server for processing. Structure from motion (SfM) photogrammetry workflows were optimized to be used without ground control. An automated change detection pipeline registers the point clouds with scale adjustment and filters vegetation. The results show that if a fixed pre-calibration of internal camera parameters is used, an accuracy close to that obtained using ground control points can be achieved. Over the study period between March 19, 2018 and June 24, 2019, a level of detection between 0.02 to 0.03 m was consistently achieved, and over 50 rockfalls between 0.003 to 0.1 m3 were detected at the study site. The design of the system is fit for purpose in terms of its ground resolution size and accuracy and can be adapted to monitor a wide range of geological and geomorphic processes at a variety of time scales.

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“…Ground Based Synthetic Aperture Radar Interferometry (GBInSAR) is an innovative remote sensing technique that allows to derive multi-temporal surface deformation maps suitable for monitoring the complex distribution of displacement fields with a high spatial-temporal resolution and an excellent accuracy and precision across slope deformation bodies [15] [38]. In particular, it allows the detection of displacement components along the sensortarget LoS with a precision range from sub-mm to a few mm and a spatial resolution with typical values of few m at a range of some km up to few cm at a range of some tens of m [39].…”

Section: Gbinsarmentioning

confidence: 99%

Innovative methods to monitor rock and mountain slope deformation

Hormes

Adams

Amabile

et al. 2020

Geomechanics and Tunnelling

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Displacement rates of mountain slope deformations that can affect entire valley mountain flanks are often measured spatially distributed in‐situ without spatial significance. The spatially explicit measurement and recording of time series of slope deformations is a challenge, as the unstable slopes are often disintegrated into several subdomains, which move with different deformation rates. The current state‐of‐the‐art monitoring systems detect slow to very slow deformation rates between mm/a and several m/a. Using the examples of slope deformations in Saalbach‐Hinterglemm and the deep rock slide Marzellkamm in Austria this paper presents the results of terrestrial laser scans, extensometer measurements, Spaceborne InSAR data, unmanned Aerial System Photogrammetry (UAS‐P), and fixed‐point measurements. The different measurements complement each other and are optimally aligned for different application areas. InSAR data can help to identify hot spots on regional and local scale, while UAS‐P enables for spatially high level accuracy in the detection of subdomains moving at different speeds. For local warning systems TLS, extensometers and GBInSAR deliver higher accuracy.

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Evidence of rock slope breathing using ground-based InSAR

Cited by 26 publications

References 47 publications

Hydromechanical Rock Slope Damage During Late Pleistocene and Holocene Glacial Cycles in an Alpine Valley

Hydromechanical Rock Slope Damage During Late Pleistocene and Holocene Glacial Cycles in an Alpine Valley

Development and Optimization of an Automated Fixed-Location Time Lapse Photogrammetric Rock Slope Monitoring System

Innovative methods to monitor rock and mountain slope deformation

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