From Toppling to Sliding: Progressive Evolution of the Moosfluh Landslide, Switzerland

Glueer, Franziska; Loew, Simon; Manconi, Andrea; Aaron, Jordan

doi:10.1029/2019jf005019

Cited by 59 publications

(53 citation statements)

References 50 publications

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“…It is interesting to note that in the absence of this immediate strength reduction, a catastrophic failure would have been unlikely to develop, and the morphology of the slope would have been more similar to that of a suspended rockslide, albeit closer to the valley floor than is typical of this landslide type. The lack of a catastrophic strength loss mechanism has been recently cited as a reason for the absence of a sudden failure of an accelerating rockslide responding to glacial retreat (Glueer et al, 2019). Aaron and Hungr (2016b) note that the simulated impact area is relatively insensitive to the transition distance from flexible block to rock avalanche, provided that the transition from solid to frictional fluid occurs once the mass has started to vacate the source zone.…”

Section: Discussionmentioning

confidence: 97%

“…Once a rockslide has failed, several runout scenarios are possible, which depend on site specific phenomena. The rockslide may displace a few meters or tens of meters (Glueer et al, 2019), disintegrate over a number of hours (Schneider et al, 1993), or transition into a catastrophic, flow-like rock avalanche (Coe et al, 2016). If catastrophic failure occurs, a rockslide may initially slide for a significant distance, translating and rotating over 3D topography, before fragmenting and becoming flow-like (Davies et al, 1999;De Blasio, 2011;Bowman et al, 2012;Aaron and Hungr, 2016b;Moore et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Understanding Failure and Runout Mechanisms of the Flims Rockslide/Rock Avalanche

et al. 2020

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The Flims rockslide/rock avalanche (FRRA) is the largest long runout landslide in Europe. This event provides a unique opportunity to study the pre-failure and failure behavior of a large rock slope, as both the source zone and deposit of this event are accessible. In this study, we perform engineering geological and geomorphic field mapping as well as stability and runout modeling in order to explore the preconditioning and triggering factors that resulted in failure of this event, and to infer the mechanisms that governed its runout. By combining these analyses, we qualitatively comment on the mechanisms that lead to the transition from a rockslide to a long runout, catastrophic rock avalanche. Our engineering geological and geomorphic field mapping has revealed that the FRRA failed along a sliding zone that features numerous, large scale steps. Previous work at the site, as well as new analysis of thin sections, has revealed the presence of marl-like layers within the failed stratigraphic unit. Our stability analysis shows that the presence of low strength layers at the depth of the rupture surface is required for failure to initiate, and that failure could be triggered either by strong seismic shaking, elevated pore-water pressures, or a combination of both. The results of the runout analysis show that this event likely remained coherent for a large portion of its motion, and that liquefaction of alluvial sediments at the toe of the slope may have enhanced the runout distance of this rock avalanche. Combining the mapping, stability and runout modeling has shown that the basal shear strength required for the runout analysis is ∼6 •-10 • lower than that back-analyzed for the stability of this event. Thus, a mechanism to reduce strength along the rupture surface immediately following the initial instability was required for catastrophic failure of this event. This mechanism is poorly understood at present, but is likely crucial for understanding the transition from an initially stable slope to a catastrophic, long runout rock avalanche.

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Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Understanding Failure and Runout Mechanisms of the Flims Rockslide/Rock Avalanche

et al. 2020

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“…Active slope instabilities in the Aletsch region (Figure 2a) Glueer, Loew, Manconi, & Aaron, 2019;Kääb, 2002;Kos et al, 2016;Loew, Gschwind, et al, 2017), as well as numerous examples of active rock slope failures in the vicinity of retreating present-day glaciers (Bovis, 1990;Cody et al, 2019;Fey et al, 2017;McColl & Davies, 2013;Oppikofer et al, 2008), provide evidence linking glacier activity and slope stability. On the other hand, prehistoric slope failures in many alpine valleys, last occupied by ice during the LGM, often cannot be connected to deglaciation as a direct trigger.…”

Section: Comparison Of Preparatory Factors For Paraglacial Rock Slopementioning

confidence: 91%

“…(e) Contour lines (20 m interval) of topography (swissALTI3D by swisstopo) and subglacial bed from ice penetrating radar data (Farinotti et al, 2009) with location of ice boreholes P1 and P2 and local ice thickness. active landslides are concentrated on both valley flanks around the retreating, present-day terminus of the Great Aletsch Glacier and have been investigated in several past studies (e.g., Glueer, Loew, Manconi, & Aaron, 2019;Kääb, 2002;Kos et al, 2016;Loew, Gschwind, et al, 2017;Strozzi et al, 2010).…”

Section: Paraglacial Setting Of the Aletsch Regionmentioning

confidence: 99%

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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“…Geodetic techniques based on GPS or total stations are also widely used and documented to remotely monitor surface displacements of active landslides (e.g. Glueer et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Development of smart boulders to monitor mass movements via the Internet of Things: A pilot study in Nepal

Dini¹,

Bennett²,

Franco³

et al. 2020

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Abstract. Boulder movement can be observed not only in rock fall activity, but also in association with other landslide types such as rock slides, soil slides in colluvium originated from previous rock slides and debris flows. Large boulders pose a direct threat to life and key infrastructure, amplifying landslide and flood hazards, as they move from the slopes to the river network. Despite the hazard they pose, boulders have not been directly targeted as a mean to detect landslide movement or used in dedicated early warning systems. We use an innovative monitoring system to observe boulder movement occurring in different geomorphological settings, before reaching the river system. Our study focuses on an area in the upper Bhote Koshi catchment northeast of Kathmandu, where the Araniko highway is subjected to periodic landsliding and floods during the monsoons and was heavily affected by coseismic landslides during the 2015 Gorkha earthquake. In the area, damage by boulders to properties, roads and other key infrastructure, such as hydropower plants, is observed every year. We embedded trackers in 23 boulders spread between a landslide body and two debris flow channels, before the monsoon season of 2019. The trackers, equipped with accelerometers, can detect small angular changes in boulders orientation and large forces acting on them. The data can be transmitted in real time, via a long-range wide area network (LoRaWAN®) gateway to a server. Nine of the tagged boulders registered patterns in the accelerometer data compatible with downslope movements. Of these, six lying within the landslide body show small angular changes, indicating a reactivation during the rainfall period and a movement consistent with the landslide mass. Three boulders, located in a debris flow channel, show sharp changes in orientation, likely corresponding to larger free movements and sudden rotations. This study highlights that this innovative, cost-effective technology can be used to monitor boulders in hazard prone sites, identifying in real time the onset of movement, and may thus set the basis for early warning systems, particularly in developing countries, where expensive hazard mitigation strategies may be unfeasible.

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From Toppling to Sliding: Progressive Evolution of the Moosfluh Landslide, Switzerland

Cited by 59 publications

References 50 publications

Understanding Failure and Runout Mechanisms of the Flims Rockslide/Rock Avalanche

Understanding Failure and Runout Mechanisms of the Flims Rockslide/Rock Avalanche

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

Development of smart boulders to monitor mass movements via the Internet of Things: A pilot study in Nepal

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