Modelling rock avalanches and their relation to permafrost degradation in glacial environments

Bottino, Giannantonio; Chiarle, Marta; Joly, A.; Mortara, G.

doi:10.1002/ppp.432

Cited by 57 publications

(43 citation statements)

References 5 publications

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“…Rockfall is common on steep cliffs adjacent to glaciers and often occurs due to a combination of debuttressing of valley walls on account of deglaciation, changing freezing and permafrost levels, short-term intense rainfall, snowfall or snowmelt, and is sometimes triggered by seismic events (Keefer, 1984;Haeberli et al, 1997;Evans and Clague, 1994;Bottino et al, 2002;Eberhart-Phillips et al, 2003). Some of the larger rockfall events result in long-runout rockslides (also referred to as 'Sturzstrom' or 'rock avalanches'), for which the horizontal runout is much larger than the vertical drop, due to transformation into granular fl ow by dynamic disintegration and/ or fl uidization.…”

Section: Introductionmentioning

confidence: 98%

Long‐runout rockslide on glacier at Tsar Mountain, Canadian Rocky Mountains: potential triggers, seismic and glaciological implications

Jiskoot

2011

Earth Surf Processes Landf

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A rhomboidal shaped rockslide with a length of 2·2 km and an area of 1·35 km 2 covers 30% of a small Clemenceau Icefi eld Group cirque glacier. By means of remote sensing, airborne photography, climate and seismic data analysis, the extent, timing, possible trigger mechanisms, and rockslide effects on the glacier are discussed. An ML 2·0 seismic event on 14 September 2000 represents the rockslide and has a spindle-shaped waveform and high energy in the low frequencies. Based on a strong signal duration of 56-108 seconds the rockslide had an average runout velocity of 22-45 m s −1 . Stress fatigue and a combination of rain and snow followed by rapid melt and night-time freezing could have co-triggered the slide. Additional seismic events with epicentres <40 km from the cirque were recorded 26 times since 1985 and range between ML 0·9-3·3, but none were caused by, or triggered, large mass movement.With a rock source volume of 1·6 × 10 6 m 3 and a deposited volume of 2-4 × 10 6 m 3 the sum of bulking and entrainment is between 25% and 150%. Five melt seasons post-event, levees 20-30 m wide tower 30 m over the surrounding glacier. Rockslide characteristics, and its Fahrböschung of 15° [height/length (H/L) = 0·28], indicate that this rockslide is quite typical for long-runout rockslides on glaciers. However, the basal friction coeffi cient was higher than found on other glaciers and could relate to the presence of medial moraines transverse to the fl owline and to pre-slide debris-cover. The difference between the coeffi cient of friction in the main fl owline (0·11-0·14) and that in a lobe confi ned between two medial moraines (0·065) suggests that confi nement increases mobility by 70-115%. Apart from reduced ablation under the rock debris, effects of the rockslide on the glacier were minimal.

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Section: Introductionmentioning

confidence: 98%

Long‐runout rockslide on glacier at Tsar Mountain, Canadian Rocky Mountains: potential triggers, seismic and glaciological implications

Jiskoot

2011

Earth Surf Processes Landf

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“…Other models of the numerical type simulate, for instance, the forces and related movement of point masses (e.g. Bottino et al, 2002). Remotely sensed data are often used to define the boundary conditions of numerical models (e.g.…”

Section: Modelling Of Hazard Potentialsmentioning

confidence: 99%

Remote sensing of glacier- and permafrost-related hazards in high mountains: an overview

Kääb

Huggel

Fischer

et al. 2005

Nat. Hazards Earth Syst. Sci.

243

149

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Abstract. Process interactions and chain reactions, the present shift of cryospheric hazard zones due to atmospheric warming, and the potential far reach of glacier disasters make it necessary to apply modern remote sensing techniques for the assessment of glacier and permafrost hazards in highmountains. Typically, related hazard source areas are situated in remote regions, often difficult to access for physical and/or political reasons. In this contribution we provide an overview of air-and spaceborne remote sensing methods suitable for glacier and permafrost hazard assessment and disaster management. A number of image classification and change detection techniques support high-mountain hazard studies. Digital terrain models (DTMs), derived from optical stereo data, synthetic aperture radar or laserscanning, represent one of the most important data sets for investigating high-mountain processes. Fusion of satellite stereo-derived DTMs with the DTM from the Shuttle Radar Topography Mission (SRTM) is a promising way to combine the advantages of both technologies. Large changes in terrain volume such as from avalanche deposits can indeed be measured even by repeat satellite DTMs. Multitemporal data can be used to derive surface displacements on glaciers, permafrost and landslides. Combining DTMs, results from spectral image classification, and multitemporal data from change detection and displacement measurements significantly improves the detection of hazard potentials. Modelling of hazardous processes based on geographic information systems (GIS) complements the remote sensing analyses towards an integrated assessment of glacier and permafrost hazards in mountains. Major present limitations in the application of remote sensing to glacier and permafrost hazards in mountains are, on the one hand, of technical nature (e.g. combination and fusion of different methods and data; improved unCorrespondence to: A. Kääb (kaeaeb@geo.unizh.ch) derstanding of microwave backscatter). On the other hand, better dissemination of remote sensing expertise towards institutions involved in high-mountain hazard assessment and management is needed in order to exploit the large potential of remote sensing in this field.

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“…These statistics are reasonably robust for rock slides and rock ice avalanches (Scheidegger, 1973;Evans and Clague, 1988;Bottino et al, 2002;Noetzli et al, 2006) and also for ice avalanches (Huggel et al, 2004a). However, they are based on observations from other mountain areas such as the Alps.…”

Section: Discussionmentioning

confidence: 99%

“…It is well established that rock slides in glacierized areas often convert into rock-ice avalanches with longer travel distances (Evans and Clague, 1988;Bottino et al, 2002). If the rock slide starts in a glacierized area, or as soon as it moves over a glacier, the relationship suggested by Noetzli et al (2006) is applied: a = −0.103, b = 0.165 for the average and −0.040 for the envelope.…”

Section: Rock Slide Hazard Indicatormentioning

confidence: 99%

Regional-scale analysis of high-mountain multi-hazard and risk indicators in the Pamir (Tajikistan) with GRASS GIS

Gruber

Mergili

2013

Nat. Hazards Earth Syst. Sci.

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Abstract. We present a model framework for the regionalscale analysis of high-mountain multi-hazard and -risk indicators, implemented with the open-source software package GRASS GIS. This framework is applied to a 98 300 km 2 study area centred in the Pamir (Tajikistan). It includes (i) rock slides, (ii) ice avalanches, (iii) periglacial debris flows and (iv) lake outburst floods. First, a hazard indicator is assigned to each relevant object (steep rock face, glacier or periglacial slope, lake). This indicator depends on the susceptibility and on the possible event magnitude. Second, the possible travel distances, impact areas and, consequently, impact hazard indicators for all types of processes are computed using empirical relationships. The impact hazard indicators are finally superimposed with an exposure indicator derived from the type of land use, resulting in a raster map of risk indicators finally discretized at the community level. The analysis results are presented and discussed at different spatial scales. The major outcome of the study, a set of comprehensive regional-scale hazard and risk indication maps, shall represent an objective basis for the prioritization of target communities for further research and risk mitigation measures.

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Modelling rock avalanches and their relation to permafrost degradation in glacial environments

Cited by 57 publications

References 5 publications

Long‐runout rockslide on glacier at Tsar Mountain, Canadian Rocky Mountains: potential triggers, seismic and glaciological implications

Long‐runout rockslide on glacier at Tsar Mountain, Canadian Rocky Mountains: potential triggers, seismic and glaciological implications

Remote sensing of glacier- and permafrost-related hazards in high mountains: an overview

Regional-scale analysis of high-mountain multi-hazard and risk indicators in the Pamir (Tajikistan) with GRASS GIS

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