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1
Caplan-Auerbach, Jacqueline, and Christian Huggel. "Precursory seismicity associated with frequent, large ice avalanches on Iliamna volcano, Alaska, USA." Journal of Glaciology 53, no. 180 (2007): 128–40. http://dx.doi.org/10.3189/172756507781833866.
Повний текст джерелаАнотація:
AbstractSince 1994, at least six major (volume >106m3) ice and rock avalanches have occurred on Iliamna volcano, Alaska, USA. Each of the avalanches was preceded by up to 2 hours of seismicity believed to represent the initial stages of failure. Each seismic sequence begins with a series of repeating earthquakes thought to represent slip on an ice–rock interface, or between layers of ice. This stage is followed by a prolonged period of continuous ground-shaking that reflects constant slip accommodated by deformation at the glacier base. Finally the glacier fails in a large avalanche. Some of the events appear to have entrained large amounts of rock, while others comprise mostly snow and ice. Several avalanches initiated from the same source region, suggesting that this part of the volcano is particularly susceptible to failure, possibly due to the presence of nearby fumaroles. Although thermal conditions at the time of failure are not well constrained, it is likely that geothermal energy causes melting at the glacier base, promoting slip and culminating in failure. The frequent nature and predictable failure sequence of Iliamna avalanches makes the volcano an excellent laboratory for the study of ice avalanches. The prolonged nature of the seismic signal suggests that warning may one day be given for similar events occurring in populated regions.
2
Aaron, Jordan, and Oldrich Hungr. "Dynamic analysis of an extraordinarily mobile rock avalanche in the Northwest Territories, Canada." Canadian Geotechnical Journal 53, no. 6 (June 2016): 899–908. http://dx.doi.org/10.1139/cgj-2015-0371.
Повний текст джерелаАнотація:
The pre-historic rock avalanche at Avalanche Lake was a spectacularly mobile rock avalanche that resulted in the largest documented runup of any landslide on earth. The runout of the 200 Mm3 event was a complex and three-dimensional process that created three distinct depositional lobes. There is some controversy as to whether the presence of glacial ice played an important role in the dynamics of this event. To investigate this hypothesis an advanced, three-dimensional numerical landslide runout model was used to reconstruct the dynamics of this event. It was found that a conventional runout model is able to reproduce the bulk characteristics of this event, including its spectacular runup, without accounting for glacial ice. A sensitivity analysis was performed to determine the factors that control the mobility of this event. It was found that low strength in the source zone, as well as the presence of significant internal strength, is required to reproduce the 600 m runup. This has important implications for the hazard analysis of rock avalanches. It appears as though large-volume rock avalanches can move with a friction angle lower than that expected for dry fragmented rock, and the runout process can be strongly influenced by internal strength. These important factors must be accounted for when performing forward analyses of this type of natural disaster.
3
Kaiser, P. K., and J. V. Simmons. "A reassessment of transport mechanisms of some rock avalanches in the Mackenzie Mountains, Yukon and Northwest Territories, Canada." Canadian Geotechnical Journal 27, no. 1 (February 1, 1990): 129–44. http://dx.doi.org/10.1139/t90-012.
Повний текст джерелаАнотація:
The transport mechanism of some rock avalanches of the Mackenzie Mountains in the Yukon and Northwest Territories of Canada is reassessed on the basis of evidence collected during fieldwork and by comparison with results from numerical simulations of the debris flow mechanism. A new hypothesis of glaciation-related transport is advanced as an alternate explanation of apparently very mobile rock avalanches with anomalous travel distances. By the example of the Avalanche Lake slide, it is demonstrated that the debris was most likely not deposited on the current topography but on valley glacier ice at an elevation of about 400–500 m above the valley bottom. This conclusion is supported by field evidence, an empirical runup relationship, and the results from numerical flow simulations. A qualitative interpretation of other debris deposits suggests that several events in the Mackenzie Mountains can be interpreted in the same manner. Key words: rock avalanches, rock slides, debris transport, debris flow modelling, Mackenzie Mountains, Northwest Territories.
4
Bhardwaj, Anshuman, and Lydia Sam. "Reconstruction and Characterisation of Past and the Most Recent Slope Failure Events at the 2021 Rock-Ice Avalanche Site in Chamoli, Indian Himalaya." Remote Sensing 14, no. 4 (February 16, 2022): 949. http://dx.doi.org/10.3390/rs14040949.
Повний текст джерелаАнотація:
Frequent ice avalanche events are being reported across the globe in recent years. On the 7 February 2021, a flash flood triggered by a rock-ice avalanche with an unusually long runout distance, caused significant damage of life and property in the Tapovan region of the Indian Himalaya. Using multi-temporal satellite datasets, digital terrain models (DTMs) and simulations, here we report the pre-event and during-event flow characteristics of two large-scale avalanches within a 5-year interval at the slope failure site. Prior to both the events, we observed short-term and long-term changes in surface velocity (SV) with maximum SVs increasing up to over 5 times the normal values. We further simulated the events to understand their mechanical characteristics leading to long runouts. In addition to its massive volume, the extraordinary magnitude of the 2021 event can partly be attributed to the possible remobilisation and entrainment of the colluvial deposits from previous ice and snow avalanches. The anomalous SVs should be explored further for their suitability as a possible remotely observable precursor of ice avalanches from hanging glaciers. This sequence of events highlights that there is a need to take into account the antecedent conditions, while making a holistic assessment of the hazard.
5
Agatova, Anna, Roman Nepop, Dmitry Ganyushkin, Demberel Otgonbayar, Semen Griga, and Ivan Ovchinnikov. "Specific Effects of the 1988 Earthquake on Topography and Glaciation of the Tsambagarav Ridge (Mongolian Altai) Based on Remote Sensing and Field Data." Remote Sensing 14, no. 4 (February 14, 2022): 917. http://dx.doi.org/10.3390/rs14040917.
Повний текст джерелаАнотація:
Strong earthquakes could serve as a trigger for glacier detachment and associated ice–rock avalanches. The 1988 Tsambagarav earthquake (M = 6.4) initiated collapse of part of the glacier tongue and a further ice–rock avalanche with an abnormal 5 km long path in Zuslan valley, Tsambagarav ridge (Mongolian Altai). Early documentation of surface effects in 1988, remote sensing and field data gathered 16 and 30 years after this event allowed for the assessment of the seismic impact on a reduction of “damaged” glacier under conditions of global warming as well as estimating topography changes in this arid and seismically active area. Because of the earthquake, the glacier immediately lost 10.4 % of its area (0.1 km2 of tongue surface). Additionally, 56% of its area was lost during 1988–2015, shrinking much faster than neighboring glaciers of similar size and exposition. Collapse of snow–ice cornice in the accumulation zone could play a key role in rapid acceleration of the detached ice block and abnormally long path of the ice–rock avalanche. A large amount of debris material provided more than 16 years of ice melting. Downstream, the valley avalanche debris cover repeats the topography of underlying Pleistocene moraines, which should be considered in regional paleogeographical reconstructions.
6
Hewitt, Kenneth. "Quaternary Moraines vs Catastrophic Rock Avalanches in the Karakoram Himalaya, Northern Pakistan." Quaternary Research 51, no. 3 (May 1999): 220–37. http://dx.doi.org/10.1006/qres.1999.2033.
Повний текст джерелаАнотація:
AbstractA history and conception of glacial events for the central Karakoram Himalaya, proposed some 80 years ago by Giotto Dainelli, are largely accepted today. However, certain deposits identified as terminal moraine complexes marking glacial episodes were actually emplaced by rock avalanches. In the Skardu and Shigar intermontane basins of Baltistan, at least 15 rock avalanche events were previously mapped as moraine or till. Criteria used for distinguishing these catastrophic landslide deposits emphasize homogeneous lithology of rubble and matrix, clast shape, facies characteristics, the large scale unity of emplacement, and morphological relations to valley topography. The deposits of three events, at Katzarah, Satpura, and the north end of Shigar Valley, have been reconstructed in detail. Thick supraglacial debris does not result in similar deposits. Extensive valley fills, river terraces, large sediment fans, and lacustrine sediments formerly attributed to late-glacial conditions are reinterpreted as postglacial events involving rock avalanches that interrupted fluvial development. Existing reconstructions of glaciations are left in doubt, especially late-glacial events in the central Karakoram, as are the roles assigned to Karakoram, main Indus Valley, and western Himalayan ice.
7
Pudasaini, Shiva P., and Michael Krautblatter. "A two-phase mechanical model for rock-ice avalanches." Journal of Geophysical Research: Earth Surface 119, no. 10 (October 2014): 2272–90. http://dx.doi.org/10.1002/2014jf003183.
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8
Toney, Liam, David Fee, Kate E. Allstadt, Matthew M. Haney, and Robin S. Matoza. "Reconstructing the dynamics of the highly similar May 2016 and June 2019 Iliamna Volcano (Alaska) ice–rock avalanches from seismoacoustic data." Earth Surface Dynamics 9, no. 2 (April 8, 2021): 271–93. http://dx.doi.org/10.5194/esurf-9-271-2021.
Повний текст джерелаАнотація:
Abstract. Surficial mass wasting events are a hazard worldwide. Seismic and acoustic signals from these often remote processes, combined with other geophysical observations, can provide key information for monitoring and rapid response efforts and enhance our understanding of event dynamics. Here, we present seismoacoustic data and analyses for two very large ice–rock avalanches occurring on Iliamna Volcano, Alaska (USA), on 22 May 2016 and 21 June 2019. Iliamna is a glacier-mantled stratovolcano located in the Cook Inlet, ∼200 km from Anchorage, Alaska. The volcano experiences massive, quasi-annual slope failures due to glacial instabilities and hydrothermal alteration of volcanic rocks near its summit. The May 2016 and June 2019 avalanches were particularly large and generated energetic seismic and infrasound signals which were recorded at numerous stations at ranges from ∼9 to over 600 km. Both avalanches initiated in the same location near the head of Iliamna's east-facing Red Glacier, and their ∼8 km long runout shapes are nearly identical. This repeatability – which is rare for large and rapid mass movements – provides an excellent opportunity for comparison and validation of seismoacoustic source characteristics. For both events, we invert long-period (15–80 s) seismic signals to obtain a force-time representation of the source. We model the avalanche as a sliding block which exerts a spatially static point force on the Earth. We use this force-time function to derive constraints on avalanche acceleration, velocity, and directionality, which are compatible with satellite imagery and observed terrain features. Our inversion results suggest that the avalanches reached speeds exceeding 70 m s−1, consistent with numerical modeling from previous Iliamna studies. We lack sufficient local infrasound data to test an acoustic source model for these processes. However, the acoustic data suggest that infrasound from these avalanches is produced after the mass movement regime transitions from cohesive block-type failure to granular and turbulent flow – little to no infrasound is generated by the initial failure. At Iliamna, synthesis of advanced numerical flow models and more detailed ground observations combined with increased geophysical station coverage could yield significant gains in our understanding of these events.
9
Leinss, Silvan, Enrico Bernardini, Mylène Jacquemart, and Mikhail Dokukin. "Glacier detachments and rock-ice avalanches in the Petra Pervogo range, Tajikistan (1973–2019)." Natural Hazards and Earth System Sciences 21, no. 5 (May 5, 2021): 1409–29. http://dx.doi.org/10.5194/nhess-21-1409-2021.
Повний текст джерелаАнотація:
Abstract. Glacier detachments are a rare, but hazardous, phenomenon of glacier instability, whereof only a handful have been documented to date. Common to all known cases is that many million cubic meters of ice detached from the bed of relatively low-angle valley glaciers and turned into long-runout mass flows. Recently, two such detachments were observed in the Petra Pervogo range in Tajikistan. Using a variety of satellite imagery, including Landsat 1–8, Sentinel-2, ASTER, TanDEM-X, WorldView, and Keyhole, we characterized these events and identified in total 17 mass flows involving glacier ice (detachments, ice, and rock-ice avalanches; rock avalanches falling on glaciers) that clustered in four different catchments between 1973 and 2019. The runout distances range from 2 to 19 km, and the largest detached glacier volume was 8.8×106 m3. A total of 11 out of 13 detachments, ice, or rock-ice avalanches occurred between July and September in years with mean annual air temperatures above the trend of the past 46 years. The relatively large number of locally clustered events indicates that the Petra Pervogo range has particularly favorable conditions for glacier instabilities. The images and geology of the region suggest that easily erodible lithologies are widespread. These soft lithologies may be also one reason for the high density of surging glaciers in the Petra Pervogo range and the wider Pamir region. We conclude that high temperatures, combined with soft, fine-grained sediments, may increase the likelihood of mass wasting events and appear to be critical factors facilitating the detachment of entire valley glaciers, whereas such events appear to be relatively robust against earthquakes for our study area. The observed recurrence of mass wasting events make the Petra Pervogo range a potential candidate to witness glacier detachments by field studies.
10
Noetzli, Jeannette, Christian Huggel, Martin Hoelzle, and Wilfried Haeberli. "GIS-based modelling of rock-ice avalanches from Alpine permafrost areas." Computational Geosciences 10, no. 2 (May 9, 2006): 161–78. http://dx.doi.org/10.1007/s10596-005-9017-z.
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11
Allen, S. K., D. Schneider, and I. F. Owens. "First approaches towards modelling glacial hazards in the Mount Cook region of New Zealand's Southern Alps." Natural Hazards and Earth System Sciences 9, no. 2 (March 31, 2009): 481–99. http://dx.doi.org/10.5194/nhess-9-481-2009.
Повний текст джерелаАнотація:
Abstract. Flood and mass movements originating from glacial environments are particularly devastating in populated mountain regions of the world, but in the remote Mount Cook region of New Zealand's Southern Alps minimal attention has been given to these processes. Glacial environments are characterized by high mass turnover and combined with changing climatic conditions, potential problems and process interactions can evolve rapidly. Remote sensing based terrain mapping, geographic information systems and flow path modelling are integrated here to explore the extent of ice avalanche, debris flow and lake flood hazard potential in the Mount Cook region. Numerous proglacial lakes have formed during recent decades, but well vegetated, low gradient outlet areas suggest catastrophic dam failure and flooding is unlikely. However, potential impacts from incoming mass movements of ice, debris or rock could lead to dam overtopping, particularly where lakes are forming directly beneath steep slopes. Physically based numerical modeling with RAMMS was introduced for local scale analyses of rock avalanche events, and was shown to be a useful tool for establishing accurate flow path dynamics and estimating potential event magnitudes. Potential debris flows originating from steep moraine and talus slopes can reach road and built infrastructure when worst-case runout distances are considered, while potential effects from ice avalanches are limited to walking tracks and alpine huts located in close proximity to initiation zones of steep ice. Further local scale studies of these processes are required, leading towards a full hazard assessment, and changing glacial conditions over coming decades will necessitate ongoing monitoring and reassessment of initiation zones and potential impacts.
12
Huggel, Christian, Jacqueline Caplan-Auerbach, Christopher F. Waythomas, and Rick L. Wessels. "Monitoring and modeling ice-rock avalanches from ice-capped volcanoes: A case study of frequent large avalanches on Iliamna Volcano, Alaska." Journal of Volcanology and Geothermal Research 168, no. 1-4 (November 2007): 114–36. http://dx.doi.org/10.1016/j.jvolgeores.2007.08.009.
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13
Huggel, C., L. Fischer, D. Schneider, and W. Haeberli. "Research advances on climate-induced slope instability in glacier and permafrost high-mountain environments." Geographica Helvetica 65, no. 2 (June 30, 2010): 146–56. http://dx.doi.org/10.5194/gh-65-146-2010.
Повний текст джерелаАнотація:
Abstract. High-mountain areas with glacier and permafrost occurrence are temperature sensitive environments. Climatic changes are, thus, likely to have an effect on slope stability. Several recent events have shown that rock and ice avalanches and related hazards can have severe consequences. For hazard analysis, the processes of slope failure and flow dynamics should therefore be better understood. In this article, recent advances in this field are presented, including high-resolution topographic monitoring of a large Alpine high-mountain flank (Monte Rosa) over the past 50 years and laboratory experiments with rotating drums and numerical modelling. This recent research has revealed important insight into the causes and dynamics of slope instabilities and contributes towards a better understanding of the influence of ice on avalanche dynamics and runout. It is emphasized that high-mountain slope failures need to be viewed from an interdisciplinary perspective, taking a number of process interactions into account.
14
Yang, Qingqing, Zhiman Su, Qiangong Cheng, Yuhao Ren, and Fei Cai. "High mobility of rock-ice avalanches: Insights from small flume tests of gravel-ice mixtures." Engineering Geology 260 (October 2019): 105260. http://dx.doi.org/10.1016/j.enggeo.2019.105260.
Повний текст джерела
15
Shroder, John, and Brandon Weihs. "Mass-Movement Disturbance Regime Landscapes, Hazards, and Water Implications: Grand Teton National Park." UW National Parks Service Research Station Annual Reports 36 (January 1, 2013): 74–87. http://dx.doi.org/10.13001/uwnpsrc.2013.3987.
Повний текст джерелаАнотація:
The Teton Range is the result of active crustal extension (normal faulting) and is the youngest range in the Rocky Mountains at approximately 2 million years old. This makes it a particularly attractive landscape to study, especially in terms of landform development and morphology because of its youth, state of seismic activity, and its recent deglaciation. These factors have combined to produce a unique fluvial landscape in that the fault-shattered metamorphic/igneous rocks of the range have been/are being eroded from their source cliffs at high rates which has covered the glacially scoured valley floors with colluvium such as talus slopes, rock slide, avalanche, and debris flow deposits. This project was focused on the characterization of all forms of mass movement, especially rock slides, multiple talus types (rockfall, alluvial, avalanche), protalus lobes, protalus ramparts, lobate and tongue-shaped rock glaciers, and their collective effects on water retention and its late-season delivery in the Grand Teton National Park, WY. A major goal of this project was to reclassify many of the mass movements in the park in an effort to streamline and simplify previous efforts by other scientists. Methods used during this study included field reconnaissance and measurements acquired during the summers of 2010 and 2013 and measurements taken from various datasets (NAIP imagery, shape files used within a GIS [ArcMap 10.0], and Google Earthâ¢). Mass movement deposits, as well as ice glaciers and long-term snowbanks, were mapped and interpreted. Overall conclusions are that the major sources of mass movements from the Archean crystalline core of the range are the result of extensive jointing, fault-shattering, increased frost-wedging at higher altitudes, slopes steepened by prior glacial erosion, and extensive snow avalanches. Areas of Paleozoic sedimentary rocks marginal to the crystalline core produce rockslides as a result of steep dips and unstable shales beneath massive overlying carbonates. The presence of internal ground ice enables development of protalus lobes, thicker rock-fragment flows, and thinner boulder streams. Such ground ice is likely to enhance late-season water delivery downstream unless climate warming and recurrent droughts become too extreme.
16
Schneider, D., R. Kaitna, W. E. Dietrich, L. Hsu, C. Huggel, and B. W. McArdell. "Frictional behavior of granular gravel–ice mixtures in vertically rotating drum experiments and implications for rock–ice avalanches." Cold Regions Science and Technology 69, no. 1 (October 2011): 70–90. http://dx.doi.org/10.1016/j.coldregions.2011.07.001.
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17
He, Chuan, Enlong Liu, Siming He, Jianhai Zhang, and Haotian Wei. "On the supraglacial rock avalanches: Thermo-hydro-mechanical analysis considering ice-water phase transition." Geomorphology 422 (February 2023): 108550. http://dx.doi.org/10.1016/j.geomorph.2022.108550.
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Pánek, Tomáš, Michal Břežný, Rachel Smedley, Diego Winocur, Elisabeth Schönfeldt, Federico Agliardi, and Kaja Fenn. "The largest rock avalanches in Patagonia: Timing and relation to Patagonian Ice Sheet retreat." Quaternary Science Reviews 302 (February 2023): 107962. http://dx.doi.org/10.1016/j.quascirev.2023.107962.
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19
Schilling, Steve P., Paul E. Carrara, Ren A. Thompson, and Eugene Y. Iwatsubo. "Posteruption glacier development within the crater of Mount St. Helens, Washington, USA." Quaternary Research 61, no. 3 (May 2004): 325–29. http://dx.doi.org/10.1016/j.yqres.2003.11.002.
Повний текст джерелаАнотація:
The cataclysmic eruption of Mount St. Helens on May 18, 1980, resulted in a large, north-facing amphitheater, with a steep headwall rising 700 m above the crater floor. In this deeply shaded niche a glacier, here named the Amphitheater glacier, has formed. Tongues of ice-containing crevasses extend from the main ice mass around both the east and the west sides of the lava dome that occupies the center of the crater floor. Aerial photographs taken in September 1996 reveal a small glacier in the southwest portion of the amphitheater containing several crevasses and a bergschrund-like feature at its head. The extent of the glacier at this time is probably about 0.1 km2. By September 2001, the debris-laden glacier had grown to about 1 km2 in area, with a maximum thickness of about 200 m, and contained an estimated 120,000,000 m3 of ice and rock debris. Approximately one-third of the volume of the glacier is thought to be rock debris derived mainly from rock avalanches from the surrounding amphitheater walls. The newly formed Amphitheater glacier is not only the largest glacier on Mount St. Helens but its aerial extent exceeds that of all other remaining glaciers combined.
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Mott, Rebecca, Andreas Wolf, Maximilian Kehl, Harald Kunstmann, Michael Warscher, and Thomas Grünewald. "Avalanches and micrometeorology driving mass and energy balance of the lowest perennial ice field of the Alps: a case study." Cryosphere 13, no. 4 (April 15, 2019): 1247–65. http://dx.doi.org/10.5194/tc-13-1247-2019.
Повний текст джерелаАнотація:
Abstract. The mass balance of very small glaciers is often governed by anomalous snow accumulation, winter precipitation being multiplied by snow redistribution processes (gravitationally or wind driven), or suppressed snow ablation driven by micrometeorological effects lowering net radiation and/or turbulent heat exchange. In this case study, we analysed the relative contribution of snow accumulation and ablation processes governing the long- and short-term mass balance of the lowest perennial ice field of the Alps, the Ice Chapel, located at 870 m a.s.l. in the Berchtesgaden National Park (Germany). This study emphasizes the importance of the local topographic setting for the survival of a perennial ice field located far below the climatic snow line. Although long-term mass balance measurements of the ice field surface showed a dramatic mass loss between 1973 and 2014, the ice field mass balance was rather stable between 2014 and 2017 and even showed a strong mass gain in 2017/2018 with an increase in surface height by 50 %–100 % relative to the ice field thickness. Measurements suggest that the winter mass balance clearly dominated the annual mass balance. At the Ice Chapel surface, 92 % of snow accumulation was gained by snow avalanching, thus clearly governing the 2017/2018 winter mass balance of the ice field with mean snow depths of 32 m at the end of the accumulation period. Avalanche deposition was amplified by preferential deposition of snowfall in the wind-sheltered rock face surrounding the ice field. Detailed micrometeorological measurements combined with a numerical analysis of the small-scale near-surface atmospheric flow field identified the micrometeorological processes driving the energy balance of the ice field. Measurements revealed a katabatic flow system draining down the ice field throughout the day, showing strong temporal and spatial dynamics. The spatial origin of the thermal flow system was shown to be of particular importance for the ice field surface energy balance. Numerical simulation indicates that deep katabatic flows, which developed at higher-elevation shaded areas of the rock face and drained down the ice field, enhance sensible heat exchange towards the ice field surface by enhancing turbulence close to the ice surface. Conversely, the shallow katabatic flow developing at the ice field surface appeared to laterally decouple the local near-surface atmosphere from the warmer adjacent air suppressing heat exchange. Numerical results thus suggest that shallow katabatic flows driven by the cooling effect of the ice field surface are especially efficient in lowering the climatic sensitivity of the ice field to the surrounding rising air temperatures. Such micrometeorological phenomena must be taken into account when calculating mass and energy balances of very small glaciers or perennial ice fields at elevations far below the climatic snow line.
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Lipovsky, Panya S., Stephen G. Evans, John J. Clague, Chris Hopkinson, Réjean Couture, Peter Bobrowsky, Göran Ekström, et al. "The July 2007 rock and ice avalanches at Mount Steele, St. Elias Mountains, Yukon, Canada." Landslides 5, no. 4 (July 17, 2008): 445–55. http://dx.doi.org/10.1007/s10346-008-0133-4.
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Zhang, Tiantian, Yang Gao, Bin Li, Yueping Yin, Xiaojie Liu, Haoyuan Gao, and Weimin Yang. "Characteristics of rock-ice avalanches and geohazard-chains in the Parlung Zangbo Basin, Tibet, China." Geomorphology 422 (February 2023): 108549. http://dx.doi.org/10.1016/j.geomorph.2022.108549.
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Nagai, Hiroto, Manabu Watanabe, Naoya Tomii, Takeo Tadono, and Shinichi Suzuki. "Multiple remote-sensing assessment of the catastrophic collapse in Langtang Valley induced by the 2015 Gorkha earthquake." Natural Hazards and Earth System Sciences 17, no. 11 (November 13, 2017): 1907–21. http://dx.doi.org/10.5194/nhess-17-1907-2017.
Повний текст джерелаАнотація:
Abstract. The main shock of the 2015 Gorkha Earthquake in Nepal induced numerous avalanches, rockfalls, and landslides in Himalayan mountain regions. A major village in the Langtang Valley was destroyed and numerous people were victims of a catastrophic avalanche event, which consisted of snow, ice, rock, and blast wind. Understanding the hazard process mainly depends on limited witness accounts, interviews, and an in situ survey after a monsoon season. To record the immediate situation and to understand the deposition process, we performed an assessment by means of satellite-based observations carried out no later than 2 weeks after the event. The avalanche-induced sediment deposition was delineated with the calculation of decreasing coherence and visual interpretation of amplitude images acquired from the Phased Array-type L-band Synthetic Aperture Radar-2 (PALSAR-2). These outline areas are highly consistent with that delineated from a high-resolution optical image of WorldView-3 (WV-3). The delineated sediment areas were estimated as 0.63 km2 (PALSAR-2 coherence calculation), 0.73 km2 (PALSAR-2 visual interpretation), and 0.88 km2 (WV-3). In the WV-3 image, surface features were classified into 10 groups. Our analysis suggests that the avalanche event contained a sequence of (1) a fast splashing body with an air blast, (2) a huge, flowing muddy mass, (3) less mass flowing from another source, (4) a smaller amount of splashing and flowing mass, and (5) splashing mass without flowing on the east and west sides. By means of satellite-derived pre- and post-event digital surface models, differences in the surface altitudes of the collapse events estimated the total volume of the sediments as 5.51 ± 0.09 × 106 m3, the largest mass of which are distributed along the river floor and a tributary water stream. These findings contribute to detailed numerical simulation of the avalanche sequences and source identification; furthermore, altitude measurements after ice and snow melting would reveal a contained volume of melting ice and snow.
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Solarski, Maksymilian, and Mirosław Szumny. "Conditions of spatiotemporal variability of the thickness of the ice cover on lakes in the Tatra Mountains." Journal of Mountain Science 17, no. 10 (October 2020): 2369–86. http://dx.doi.org/10.1007/s11629-019-5907-8.
Повний текст джерелаАнотація:
Abstract This research aimed to identify the impact of local climatic and topographic conditions on the formation and development of the ice cover in high-mountain lakes and the representativeness assessment of periodic point measurements of the ice cover thickness by taking into consideration the role of the avalanches on the icing of the lakes. Field works included measurement of the ice and snow cover thickness of seven lakes situated in the Tatra Mountains (UNESCO biosphere reserve) at the beginning and the end of the 2017/2018 winter season. In addition, morphometric, topographic and daily meteorological data of lakes from local IMGW (Polish Institute of Meteorology and Water Management) stations and satellite images were used. The obtained results enabled us to quantify the impact of the winter eolian snow accumulation on the variation in ice thickness. This variation was ranging from several centimetres up to about 2 meters and had a tendency to increase during the winter season. The thickest ice covers occurred in the most shaded places in the direct vicinity of rock walls. The obtained results confirm a dominating role of the snow cover in the variation of the ice thickness within individual lakes.
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Ren, Yuhao, Qingqing Yang, Qiangong Cheng, Fei Cai, and Zhiman Su. "Solid-liquid interaction caused by minor wetting in gravel-ice mixtures: A key factor for the mobility of rock-ice avalanches." Engineering Geology 286 (June 2021): 106072. http://dx.doi.org/10.1016/j.enggeo.2021.106072.
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Mohamadi, B., and T. Balz. "MEASURING SURFACE DEFORMATION IN GLACIER RETREATED AREAS BASED ON PS-INSAR – GELADANDONG GLACIER AS A CASE STUDY." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3 (April 30, 2018): 1285–89. http://dx.doi.org/10.5194/isprs-archives-xlii-3-1285-2018.
Повний текст джерелаАнотація:
Glaciers are retreating in many parts of the world as a result of global warming. Many researchers consider Qinghai-Tibetan Plateau as a reference for climate change by measuring glaciers retreat on the plateau. This retreat resulted in some topographic changes in retreated areas, and in some cases can lead to geohazards as landslides, and rock avalanches, which is known in glacier retreated areas as paraglacial slope failure (PSF). In this study, Geladandong biggest and main glacier mass was selected to estimate surface deformation on its glacier retreated areas and define potential future PSF based on PS-InSAR technique. 56 ascending and 49 descending images were used to fulfill this aim. Geladandong glacier retreated areas were defined based on the maximum extent of the glacier in the little ice age. Results revealed a general uplift in the glacier retreated areas with velocity less than 5mm/year. Obvious surface motion was revealed in seven parts surround glacier retreated areas with high relative velocity reached ±60mm/year in some parts. Four parts were considered as PSF potential motion, and two of them showed potential damage for the main road in the study area in case of rock avalanche into recent glacier lakes that could result in glacier lake outburst flooding heading directly to the road. Finally, further analysis and field investigations are needed to define the main reasons for different types of deformation and estimate future risks of these types of surface motion in the Qinghai-Tibetan Plateau.
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Morino, Costanza, Susan J. Conway, Matthew R. Balme, Jón Kristinn Helgason, Þorsteinn Sæmundsson, Colm Jordan, John Hillier, and Tom Argles. "The impact of ground-ice thaw on landslide geomorphology and dynamics: two case studies in northern Iceland." Landslides 18, no. 8 (May 4, 2021): 2785–812. http://dx.doi.org/10.1007/s10346-021-01661-1.
Повний текст джерелаАнотація:
AbstractAs consequence of ongoing climate change, permafrost degradation is thought to be increasingly affecting slope stability in periglacial environments. This is of growing concern in Iceland, where in the last decade, permafrost degradation has been identified among the triggering factors of landslides. The role of ground ice in conditioning the morphology and dynamics of landslides involving loose deposits is poorly understood. We show the geomorphological impact of the Móafellshyrna and Árnesfjall landslides that recently occurred in ice-cemented talus deposits in northern Iceland. Using field and aerial remote-sensing measurements of the morphological and morphometric characteristics of the landslides, we assess the influence of thawing ground ice on their propagation style and dynamics. The two mass movements are complex and are similar to rock- and debris-ice avalanches, changing trajectory and exhibiting evidence of transitioning their style of motion from a dry granular mass to a debris flow-like movement via multiple pulses. We infer that the thawing of ground ice together with the entrainment of saturated material provided the extra fluid causing this change in dynamics. The hazardous consequences of permafrost degradation will increasingly affect mountain regions in the future, and ground-ice thaw in steep terrain is a particularly hazardous phenomenon, as it may induce unexpected long-runout failures and can cause slope instability to continue even after the landslide event. Our study expands our knowledge of how landslides develop in unstable ice-cemented deposits and will aid assessment and mitigation of the hazard that they pose in Iceland and other mountainous periglacial areas.
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Haeberli, W., J. C. Alean, P. Müller, and M. Funk. "Assessing Risks from Glacier Hazards in High Mountain Regions: Some Experiences in the Swiss Alps." Annals of Glaciology 13 (1989): 96–102. http://dx.doi.org/10.3189/s0260305500007709.
Повний текст джерелаАнотація:
Assessing risks from potential glacier hazards in relation to safety considerations for settlements and other fixed installations in high mountain areas requires the application of experience gained from previous events, combined with simple rules derived from basic glaciological theory. The general characteristics of steep, and usually unmeasured, glaciers can be estimated on the basis of a rough parameterization scheme. Variations in glacier length, ice avalanches, and glacier floods then have to be considered for time periods ranging from a few years up to a few decades. As a result of such systematic assessments, maps of potentially dangerous zones can be prepared. Although the inhabitants of many Alpine villages have always lived with the risk of glacier hazards, it now appears that modern construction work, especially that connected with the development of tourism, has started to infiltrate previously avoided high-risk zones more and more. In order to plan reasonable safety measures, risks from glacier hazards have to be compared with those from other natural hazards in mountain areas, such as snow avalanches, landslides, rock falls! or storm-induced floods. Decisions about the acceptable level of risk are difficult and subjective; they are also often influenced by political and economical considerations rather than by scientific reasoning.
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Haeberli, W., J. C. Alean, P. Müller, and M. Funk. "Assessing Risks from Glacier Hazards in High Mountain Regions: Some Experiences in the Swiss Alps." Annals of Glaciology 13 (1989): 96–102. http://dx.doi.org/10.1017/s0260305500007709.
Повний текст джерелаАнотація:
Assessing risks from potential glacier hazards in relation to safety considerations for settlements and other fixed installations in high mountain areas requires the application of experience gained from previous events, combined with simple rules derived from basic glaciological theory. The general characteristics of steep, and usually unmeasured, glaciers can be estimated on the basis of a rough parameterization scheme. Variations in glacier length, ice avalanches, and glacier floods then have to be considered for time periods ranging from a few years up to a few decades. As a result of such systematic assessments, maps of potentially dangerous zones can be prepared. Although the inhabitants of many Alpine villages have always lived with the risk of glacier hazards, it now appears that modern construction work, especially that connected with the development of tourism, has started to infiltrate previously avoided high-risk zones more and more. In order to plan reasonable safety measures, risks from glacier hazards have to be compared with those from other natural hazards in mountain areas, such as snow avalanches, landslides, rock falls! or storm-induced floods. Decisions about the acceptable level of risk are difficult and subjective; they are also often influenced by political and economical considerations rather than by scientific reasoning.
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Gruber, F. E., and M. Mergili. "Regional-scale analysis of high-mountain multi-hazard and risk in the Pamir (Tajikistan) with GRASS GIS." Natural Hazards and Earth System Sciences Discussions 1, no. 2 (April 26, 2013): 1689–747. http://dx.doi.org/10.5194/nhessd-1-1689-2013.
Повний текст джерелаАнотація:
Abstract. We present a model framework for the regional-scale analysis of high-mountain multi-hazard and -risk, implemented with the Open Source software package GRASS GIS. This framework is applied to a 98 300 km2 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 indication score is assigned to each relevant object (steep rock face, glacier or periglacial slope, lake). This score depends on the susceptibility and on the expected event magnitude. Second, the possible travel distances, impact areas and, consequently, impact hazard indication scores for all types of processes are computed using empirical relationships. These scores are finally superimposed with an exposure score derived from the type of land use, resulting in a raster map of risk indication scores 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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Gruber, F. E., and M. Mergili. "Regional-scale analysis of high-mountain multi-hazard and risk indicators in the Pamir (Tajikistan) with GRASS GIS." Natural Hazards and Earth System Sciences 13, no. 11 (November 7, 2013): 2779–96. http://dx.doi.org/10.5194/nhess-13-2779-2013.
Повний текст джерелаАнотація:
Abstract. We present a model framework for the regional-scale 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 km2 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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Lilleøren, Karianne S., Bernd Etzelmüller, Line Rouyet, Trond Eiken, Gaute Slinde, and Christin Hilbich. "Transitional rock glaciers at sea level in northern Norway." Earth Surface Dynamics 10, no. 5 (October 17, 2022): 975–96. http://dx.doi.org/10.5194/esurf-10-975-2022.
Повний текст джерелаАнотація:
Abstract. Rock glaciers are geomorphological expressions of permafrost. Close to sea level in northernmost Norway, in the subarctic Nordkinn peninsula, we have observed several rock glaciers that appear to be active now or were active in the recent past. Active rock glaciers at this elevation have never before been described in Fennoscandia, and they are outside the climatic limits of present-day permafrost according to models. In this study, we have investigated whether or not these rock glaciers are active under the current climate situation. We made detailed geomorphological maps of three rock glacier areas in Nordkinn and investigated the regional ground dynamics using synthetic aperture radar interferometry (InSAR). One of the rock glaciers, namely the Ivarsfjorden rock glacier, was investigated in more detail by combining observations of vertical and horizontal changes from optical images acquired by airborne and terrestrial sensors and terrestrial laser scans (TLSs). The subsurface of the same rock glacier was investigated using a combination of electrical resistivity tomography (ERT) and refraction seismic tomography (RST). We also measured ground surface temperatures between 2016 and 2020, complemented by investigations using an infrared thermal camera, and a multi-decadal climatic analysis. We mapped the rock glaciers in the innermost parts of Store and Lille Skogfjorden as relict, while the more active ones are in the mouths of both fjords, fed by active talus in the upper slopes. Several of the rock glaciers cross over both the Younger Dryas shoreline (25 m a.s.l.) and the Early to Mid-Holocene shoreline at 13 m a.s.l. Both InSAR and optical remote sensing observations reveal low yearly movement rates (centimetres to millimetres per year). The ERT and RST suggest that there is no longer permafrost and ground ice in the rock glacier, while temperature observations on the front slope indicate freezing conditions also in summer. Based on the in situ temperature measurements and the interpolated regional temperature data, we show that the mean annual air temperature (MAAT) of the region has risen by 2 ∘C since the late 19th century to about 1.5 ∘C in the last decade. MAATs below 0 ∘C 100–150 years ago suggest that new rock glacier lobes may have formed at the end of the Little Ice Age (LIA). These combined results indicate that the Nordkinn rock glaciers are transitioning from active to relict stages. The study shows that transitional rock glaciers are still affected by creep, rock falls, snow avalanches, etc., and are not entirely dynamically dead features. Our contrasting results concerning permafrost presence and rock glacier activity show the importance of a multi-methodological approach when investigating slope processes in the edge zones of permafrost influence.
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Jaedicke, C., K. Lied, and K. Kronholm. "Integrated database for rapid mass movements in Norway." Natural Hazards and Earth System Sciences 9, no. 2 (March 31, 2009): 469–79. http://dx.doi.org/10.5194/nhess-9-469-2009.
Повний текст джерелаАнотація:
Abstract. Rapid gravitational slope mass movements include all kinds of short term relocation of geological material, snow or ice. Traditionally, information about such events is collected separately in different databases covering selected geographical regions and types of movement. In Norway the terrain is susceptible to all types of rapid gravitational slope mass movements ranging from single rocks hitting roads and houses to large snow avalanches and rock slides where entire mountainsides collapse into fjords creating flood waves and endangering large areas. In addition, quick clay slides occur in desalinated marine sediments in South Eastern and Mid Norway. For the authorities and inhabitants of endangered areas, the type of threat is of minor importance and mitigation measures have to consider several types of rapid mass movements simultaneously. An integrated national database for all types of rapid mass movements built around individual events has been established. Only three data entries are mandatory: time, location and type of movement. The remaining optional parameters enable recording of detailed information about the terrain, materials involved and damages caused. Pictures, movies and other documentation can be uploaded into the database. A web-based graphical user interface has been developed allowing new events to be entered, as well as editing and querying for all events. An integration of the database into a GIS system is currently under development. Datasets from various national sources like the road authorities and the Geological Survey of Norway were imported into the database. Today, the database contains 33 000 rapid mass movement events from the last five hundred years covering the entire country. A first analysis of the data shows that the most frequent type of recorded rapid mass movement is rock slides and snow avalanches followed by debris slides in third place. Most events are recorded in the steep fjord terrain of the Norwegian west coast, but major events are recorded all over the country. Snow avalanches account for most fatalities, while large rock slides causing flood waves and huge quick clay slides are the most damaging individual events in terms of damage to infrastructure and property and for causing multiple fatalities. The quality of the data is strongly influenced by the personal engagement of local observers and varying observation routines. This database is a unique source for statistical analysis including, risk analysis and the relation between rapid mass movements and climate. The database of rapid mass movement events will also facilitate validation of national hazard and risk maps.
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Gilbert, Adrien, Silvan Leinss, Jeffrey Kargel, Andreas Kääb, Simon Gascoin, Gregory Leonard, Etienne Berthier, Alina Karki, and Tandong Yao. "Mechanisms leading to the 2016 giant twin glacier collapses, Aru Range, Tibet." Cryosphere 12, no. 9 (September 7, 2018): 2883–900. http://dx.doi.org/10.5194/tc-12-2883-2018.
Повний текст джерелаАнотація:
Abstract. In north-western Tibet (34.0∘ N, 82.2∘ E) near lake Aru Co, the entire ablation areas of two glaciers (Aru-1 and Aru-2) suddenly collapsed on 17 July and 21 September 2016. The masses transformed into ice avalanches with volumes of 68 and 83×106 m3 and ran out up to 7 km in horizontal distance, killing nine people. The only similar event currently documented is the 130×106 m3 Kolka Glacier rock and ice avalanche of 2002 (Caucasus Mountains). Using climatic reanalysis, remote sensing, and three-dimensional thermo-mechanical modelling, we reconstructed the Aru glaciers' thermal regimes, thicknesses, velocities, basal shear stresses, and ice damage prior to the collapse in detail. Thereby, we highlight the potential of using emergence velocities to constrain basal friction in mountain glacier models. We show that the frictional change leading to the Aru collapses occurred in the temperate areas of the polythermal glaciers and is not related to a rapid thawing of cold-based ice. The two glaciers experienced a similar stress transfer from predominant basal drag towards predominant lateral shearing in the detachment areas and during the 5–6 years before the collapses. A high-friction patch is found under the Aru-2 glacier tongue, but not under the Aru-1 glacier. This difference led to disparate behaviour of both glaciers, making the development of the instability more visible for the Aru-1 glacier through enhanced crevassing and terminus advance over a longer period. In comparison, these signs were observable only over a few days to weeks (crevasses) or were absent (advance) for the Aru-2 glacier. Field investigations reveal that those two glaciers were underlain by soft, highly erodible, and fine-grained sedimentary lithologies. We propose that the specific bedrock lithology played a key role in the two Tibet and the Caucasus Mountains giant glacier collapses documented to date by producing low bed roughness and large amounts of till, rich in clay and silt with a low friction angle. The twin 2016 Aru collapses would thus have been driven by a failing basal substrate linked to increasing pore water pressure in the subglacial drainage system in response to increases in surface melting and rain during the 5–6 years preceding the collapse dates.
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Kääb, Andreas, Mylène Jacquemart, Adrien Gilbert, Silvan Leinss, Luc Girod, Christian Huggel, Daniel Falaschi, et al. "Sudden large-volume detachments of low-angle mountain glaciers – more frequent than thought?" Cryosphere 15, no. 4 (April 12, 2021): 1751–85. http://dx.doi.org/10.5194/tc-15-1751-2021.
Повний текст джерелаАнотація:
Abstract. The detachment of large parts of low-angle mountain glaciers resulting in massive ice–rock avalanches have so far been believed to be a unique type of event, made known to the global scientific community first for the 2002 Kolka Glacier detachment, Caucasus Mountains, and then for the 2016 collapses of two glaciers in the Aru range, Tibet. Since 2016, several so-far unrecognized low-angle glacier detachments have been recognized and described, and new ones have occurred. In the current contribution, we compile, compare, and discuss 20 actual or suspected large-volume detachments of low-angle mountain glaciers at 10 different sites in the Caucasus, the Pamirs, Tibet, Altai, the North American Cordillera, and the Southern Andes. Many of the detachments reached volumes in the order of 10–100 million m3. The similarities and differences between the presented cases indicate that glacier detachments often involve a coincidental combination of factors related to the lowering of basal friction, high or increasing driving stresses, concentration of shear stress, or low resistance to exceed stability thresholds. Particularly soft glacier beds seem to be a common condition among the observed events as they offer smooth contact areas between the glacier and the underlying substrate and are prone to till-strength weakening and eventually basal failure under high pore-water pressure. Partially or fully thawed glacier bed conditions and the presence of liquid water could thus play an important role in the detachments. Surface slopes of the detached glaciers range between around 10∘ and 20∘. This may be low enough to enable the development of thick and thus large-volume glaciers while also being steep enough to allow critical driving stresses to build up. We construct a simple slab model to estimate ranges of glacier slope and width above which a glacier may be able to detach when extensively losing basal resistance. From this model we estimate that all the detachments described in this study occurred due to a basal shear stress reduction of more than 50 %. Most of the ice–rock avalanches resulting from the detachments in this study have a particularly low angle of reach, down to around 5∘, likely due to their high ice content and connected liquefaction potential, the availability of soft basal slurries, and large amounts of basal water, as well as the smooth topographic setting typical for glacial valleys. Low-angle glacier detachments combine elements and likely also physical processes of glacier surges and ice break-offs from steep glaciers. The surge-like temporal evolution ahead of several detachments and their geographic proximity to other surge-type glaciers indicate the glacier detachments investigated can be interpreted as endmembers of the continuum of surge-like glacier instabilities. Though rare, glacier detachments appear to be more frequent than commonly thought and disclose, despite local differences in conditions and precursory evolutions, the fundamental and critical potential of low-angle soft glacier beds to fail catastrophically.
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Shah, S. K. Ali, G. Khan, S. Ali, J. A. Qureshi, N. Habib, and A. Khan. "MULTI-HAZARD RISK ASSESSMENT OF QURUMBAR VALLEY, GHIZER, GILGIT BALTISTAN, PAKISTAN." Journal of Mountain Area Research 4 (December 23, 2019): 24. http://dx.doi.org/10.53874/jmar.v4i0.63.
Повний текст джерелаАнотація:
Being located in a seismically active zone, these mountain valleys are exposed to different hydro-meteorological hazards like rockfall, debris flow, landslide, ice avalanches, and glacial lake outburst flood (GLOFs). The present study is to investigate different multi-hazards and their prevailing risk in the particular area of Qurumbar valley Ishkoman. In the mid-nineteen and twenty centuries at least six devastating glacial lake outburst floods (GLOFs) has been recorded, initially, only the Qurumbar glacier was considered as the main cause of this outburst flood, later field investigation and interview from local inhabitant revealed that nine more tributary glacier are existing in the area. The recent outburst of flood in the Badswat area of Qurumbar Ishkoman is also considerable, submerging 12 houses and a stretch of roads. Apart from it, the physical vulnerability of the area is increasing, as new areas are being used for housing with the increase in population. The study area is exposed to several other natural hazards like rock fall, debris flows, ice avalanches, and bank erosion. The present study is based on quantitative and qualitative approaches in assistance with GIS/RS an emergent application. The following methodologies were adapted to gather the primary and secondary data for GIS/RS processing. The primary data comprises GIS data and procurement and development and field data. The field data contain ground-truthing /validation. The community-based Hazard Vulnerability Risk Assessment (HVRA) was also carried out to know about human perception. Secondary data has been collected from different literature. Both the data were put into GIS for the processing which gives us our final developmental tools in the form of maps. The hazard and risk map of the Qurumbar Ishkoman depict that flash floods, debris flow, bank erosion, and GLOFs account for major hazards in Qurumbar valley. It is concluded based on our outcomes i.e., hazard and risk maps that earthquake is the main hazard of the area while flash floods, GLOFs, debris flow, bank erosion and the bank collapsed are the main hazards of the area. It is very important to systematically integrate map information into the planning and management process which contributes to a safer environment.
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Allen, Simon K., Ashim Sattar, Owen King, Guoqing Zhang, Atanu Bhattacharya, Tandong Yao, and Tobias Bolch. "Glacial lake outburst flood hazard under current and future conditions: worst-case scenarios in a transboundary Himalayan basin." Natural Hazards and Earth System Sciences 22, no. 11 (November 23, 2022): 3765–85. http://dx.doi.org/10.5194/nhess-22-3765-2022.
Повний текст джерелаАнотація:
Abstract. Glacial lake outburst floods (GLOFs) are a major concern throughout High Mountain Asia, where societal impacts can extend far downstream. This is particularly true for transboundary Himalayan basins, where risks are expected to further increase as new lakes develop. Given the need for anticipatory approaches to disaster risk reduction, this study aims to demonstrate how the threat from a future lake can be feasibly assessed alongside that of worst-case scenarios from current lakes, as well as how this information is relevant for disaster risk management. We have focused on two previously identified dangerous lakes (Galongco and Jialongco), comparing the timing and magnitude of simulated worst-case outburst events from these lakes both in the Tibetan town of Nyalam and downstream at the border with Nepal. In addition, a future scenario has been assessed, whereby an avalanche-triggered GLOF was simulated for a potential large new lake forming upstream of Nyalam. Results show that large (>20×106 m3) rock and/or ice avalanches could generate GLOF discharges at the border with Nepal that are more than 15 times larger than what has been observed previously or anticipated based on more gradual breach simulations. For all assessed lakes, warning times in Nyalam would be only 5–11 min and 30 min at the border. Recent remedial measures undertaken to lower the water level at Jialongco would have little influence on downstream impacts resulting from a very large-magnitude GLOF, particularly in Nyalam where there has been significant development of infrastructure directly within the high-intensity flood zone. Based on these findings, a comprehensive approach to disaster risk management is called for, combining early warning systems with effective land use zoning and programmes to build local response capacities. Such approaches would address the current drivers of GLOF risk in the basin while remaining robust in the face of worst-case, catastrophic outburst events that become more likely under a warming climate.
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Kattel, Parameshwari, Khim B. Khattri, Puskar R. Pokhrel, Jeevan Kafle, Bhadra Man Tuladhar, and Shiva P. Pudasaini. "Simulating glacial lake outburst floods with a two-phase mass flow model." Annals of Glaciology 57, no. 71 (March 2016): 349–58. http://dx.doi.org/10.3189/2016aog71a039.
Повний текст джерелаАнотація:
AbstractTo simulate a glacial lake outburst flood, we employ a comprehensive physically based general two-phase mass flow model (Pudasaini, 2012). This model accounts for a strong interaction between the solid and fluid phases and incorporates buoyancy and other dominant physical aspects of the mass flows such as enhanced non-Newtonian viscous stress, virtual mass force and generalized drag. Our real two-phase mass flow simulation describes explicit evolution of the solid and fluid phases and the debris bulk as a whole, akin to torrential debris flows or debris floods during glacial lake outburst floods (GLOFs). The emptying of a lake following rapid collapse of a restraining dam, the consequent downslope motion of a mixed solid–fluid mass, and the tendency of the mass to form extruding plumes are analyzed in detail for different flow configurations, volumes, conduit geometries and boundary conditions. The solid and fluid phases evolve completely differently and reveal fundamentally different dynamical behaviours. During the flow, the relatively long fluid tail follows the solid-rich dense frontal surge head. The bulk debris develops into a frontal and side levee as derived from the initial frontal moraine dam. Results show that our high-resolution, unified simulation strategies and the advanced model equations can be applied to study the flow dynamics of a wide range of geophysical mass flows such as snow and rock–ice avalanches, debris flows and flash floods as well as GLOFs. This may help substantially in forming a basis for appropriate mitigation measures against potential natural hazards in high mountain slopes and valleys.
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Mergili, Martin, Michel Jaboyedoff, José Pullarello, and Shiva P. Pudasaini. "Back calculation of the 2017 Piz Cengalo–Bondo landslide cascade with r.avaflow: what we can do and what we can learn." Natural Hazards and Earth System Sciences 20, no. 2 (February 21, 2020): 505–20. http://dx.doi.org/10.5194/nhess-20-505-2020.
Повний текст джерелаАнотація:
Abstract. In the morning of 23 August 2017, around 3×106 m3 of granitoid rock broke off from the eastern face of Piz Cengalo, southeastern Switzerland. The initial rockslide–rockfall entrained 6×105m3 of a glacier and continued as a rock (or rock–ice) avalanche before evolving into a channelized debris flow that reached the village of Bondo at a distance of 6.5 km after a couple of minutes. Subsequent debris flow surges followed in the next hours and days. The event resulted in eight fatalities along its path and severely damaged Bondo. The most likely candidates for the water causing the transformation of the rock avalanche into a long-runout debris flow are the entrained glacier ice and water originating from the debris beneath the rock avalanche. In the present work we try to reconstruct conceptually and numerically the cascade from the initial rockslide–rockfall to the first debris flow surge and thereby consider two scenarios in terms of qualitative conceptual process models: (i) entrainment of most of the glacier ice by the frontal part of the initial rockslide–rockfall and/or injection of water from the basal sediments due to sudden rise in pore pressure, leading to a frontal debris flow, with the rear part largely remaining dry and depositing mid-valley, and (ii) most of the entrained glacier ice remaining beneath or behind the frontal rock avalanche and developing into an avalanching flow of ice and water, part of which overtops and partially entrains the rock avalanche deposit, resulting in a debris flow. Both scenarios can – with some limitations – be numerically reproduced with an enhanced version of the two-phase mass flow model (Pudasaini, 2012) implemented with the simulation software r.avaflow, based on plausible assumptions of the model parameters. However, these simulation results do not allow us to conclude on which of the two scenarios is the more likely one. Future work will be directed towards the application of a three-phase flow model (rock, ice, and fluid) including phase transitions in order to better represent the melting of glacier ice and a more appropriate consideration of deposition of debris flow material along the channel.
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Lamsal, Sudip, Nabaraj Sapkota, Arjun Bhandari, Ishor Gyanwali, Kabi Raj Paudyal, and Lalu Paudel. "Geological investigation of river terraces along the Modi Khola valley, Parbat district, western Nepal Lesser Himalaya." Journal of Nepal Geological Society 53 (December 31, 2017): 31–37. http://dx.doi.org/10.3126/jngs.v53i0.23798.
Повний текст джерелаАнотація:
Fluvial terraces are remnants of the former floodplain of a stream or river. Wide river valley with spectacular terraces are the well-known places of the Himalaya because of their unique morphology and history of origin. The Modi Khola and Kali Gandaki valleys in west Nepal, Lesser Himalaya are characterized by a number of spectacular river terraces. In the present study, the river terraces along the Modi Khola valley were mapped at 1:25,000 scale and their lithological and sedimentological characteristics were investigated. The river terraces along the Modi Khola are distributed in at least three levels. They are named as Godam Formation (Higger Terrace), Badagaun Formation (Middle Terrace) and the Modibeni Formation (Lower Terrace). The Godam Formation is standing out at an elevation between 860 m and 1100 m. The upper surface of the terrace is extremely rugged with karstic features. The Godam Formation is characterized by matrix-supported, calcite cemented conglomerate with angular to sub-angular clasts of calcareous shale, laminated siliceous limestone and quartzite. The Badagaun Formation (Middle Terrace) is distributed at an altitude from 700 to 860 m on both sides of the Modi Khola valley. It is deeply weathered forming a very thick (almost 3-5 m) residual soil (mostly lateritic soil). Karst features such as caves and sink holes are common in this terrace. This formation is mainly composed of matrix-supported conglomerate with granule-, cobble- and boulder-sized clasts of calcareous shale, siliceous limestone and rarely quartzite. The Lower Terrace (Modibeni Formation) is fluvial deposit consisting of rounded and subrounded clast-supported conglomerate. Both the Upper and Middle Terraces have been interpreted as cohesive debris flow facies derived from the Annapurna Range. Presence of three levels of terraces indicates at least three phase of uplift in the area in the Holocene time. The debris flow deposit in the upper and Middle Terraces indicates catastrophic outbursts from natural dams or large rock-ice avalanches in the Annapurna Range triggered probably by megaearthquakes as in Pokhara valley as suggested by Schwanghart et al. (2015).
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Evans, S. G., O. Hungr, and E. G. Enegren. "The Avalanche Lake rock avalanche, Mackenzie Mountains, Northwest Territories, Canada: description, dating, and dynamics." Canadian Geotechnical Journal 31, no. 5 (October 1, 1994): 749–68. http://dx.doi.org/10.1139/t94-086.
Повний текст джерелаАнотація:
At Avalanche Lake, located in the Backbone Ranges of the Mackenzie Mountains, about 200 × 106 m3 of massive Devonian carbonate rock slid down remarkably planar bedding surfaces dipping at 30° and created a spectacular runup on the opposite valley side onto a topographic feature called the Shelf. The interpretation of events at Avalanche Lake has recently been subject to controversy. It has been argued by other workers that the rock avalanche could not have run onto the Shelf without glacier ice partially filling the valley, thus reducing the magnitude of the actual runup, and implying that the rock avalanche took place at the end of the Pleistocene. Evidence is presented indicating that the rock avalanche occurred in an ice-free environment. It consists of the nature of the detachment surface, the morphology and location of the rock avalanche debris, the presence of levees in the debris and isolated patches of debris on valley-side slopes, and the entrainment of alluvial deposits and conifer fragments from the valley floor in the Shelf Lobe debris. In addition, radiocarbon ages obtained from entrained wood in the debris, converted to calendric years, indicate that the landslide took place in this millennium, with a 95% probability of it having occurred no earlier than 1440 A.D. No glacier ice then existed in the valley. Based on this evidence the behaviour of the rock avalanche is reconstructed. It is characterized by dramatic mobility in which the rock avalanche split into two parts. The west part smashed into the opposite valley side and about 5 × 106 m3 rode up onto the Shelf. The remainder (155 × 106 m3) fell back into the valley, partially running back up the detachment surface to an elevation 360 m above the valley, and then, reversing direction again, ran back into the valley bottom where it was deposited. The east part, the South Lobe (40 × 106 m3), ran down a valley reentrant opposite the detachment surface. The maximum vertical drop in the path is 1220 m, and the maximum runup is 640 m. The fahrböschung is 8° for the Shelf Lobe and 10° for the South Lobe. An analysis of the movement of the centre of gravity using a version of Koerner's dynamic model simulates the runup onto the Shelf, indicating that the presence of glacier ice is not necessary to account for the runup magnitude. Estimated maximum velocities during the movement reached 80 m/s. The runup is the highest recorded and on an empirical runup plot is highly anomalous in relation to the height of the descent slope. The case history illustrates the limitation of a dynamic model applied to a rock avalanche when it is assumed that the centre of gravity of the mass is displaced from the highest point on the detachment surface to the farthest tip of the debris. It also demonstrates that massive detachments have taken place in the Mackenzie Mountains in the comparatively recent past. Key words : rock avalanche, runup, Avalanche Lake, dynamics, radiocarbon dating, Mackenzie Mountains.
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Sanders, Diethard, Hannah Pomella, and Charlotte Gild. "Early late-glacial rock avalanche and its lasting effects on drainage and sediment dispersal (Strassberg valley catchment, Northern Calcareous Alps, Austria)." Austrian Journal of Earth Sciences 111, no. 2 (December 1, 2018): 180–203. http://dx.doi.org/10.17738/ajes.2018.0012.
Повний текст джерелаАнотація:
AbstractIn intramontane landscapes shaped by glacial-interglacial cycles, the most rapid changes during the proglacial/paraglacial phases may be amplified by catastrophic mass-wasting. Herein, we describe the Last Glacial Maximum (LGM) to Holocene development of a catchment in the Northern Calcareous Alps wherein intense proglacial/paraglacial sedimentation and descend of a rock avalanche persistently modified drainage and sediment dispersal.During buildup of the LGM, the pre-last glacial Strassberg valley – the trunk valley of this study – was filled with a proglacial fluvio-lacustrine succession. Thereafter, the area became largely buried under the Inn ice stream. During deglacial ice melt, copious sediment was shed from glacially-conditioned mountain flanks. Alluvial fans cut off from their former supply area, and perched in isolated position, result from presumed sediment dispersal across dead ice. Shortly after deglaciation, a ~11 Mm3 rock avalanche detached from a high cliff, overran an opposing mountain ridge, and spread over a lower-positioned plateau. The rock avalanche blocked the Strassberg valley and set the base-level to an intramontane basin that persists until present. A quartz OSL age from a loess drape above the rock-avalanche deposit dates mass wasting prior to 18.77 ± 1.55 ka; so far, this is the oldest age-bracketed post-LGM catastrophic mass-wasting of the Eastern Alps.After mass wasting, the valley was barred by the rock-avalanche deposit. This, in turn, triggered a westward switch of drainage thalweg and stream incision. The present Strassberg valley is an epigenetic bedrock gorge 1.5 km in length and down to 100 m in depth. A 234U/230Th calcite disequilibrium age of 9 ± 1 ka from cemented talus indicates that most incision took place during the late-glacial to early Holocene. Aside of the large-scale morphology (valleys, ranges) the drainage, the smaller-scale morphology, and the sediment volumes of the study area are mainly coined by proglacial/paraglacial processes and by rock avalanching. Holocene landscape changes are modest and chiefly comprise aggradation of high-positioned scree slopes, colluvial/alluvial redeposition and stream incision, and slope stabilization by reforestation. Our results underscore that intramontane sceneries are mosaics with respect to the age of landforms and that large parts of the landscape still are off geomorphic equilibrium with interglacial conditions.
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Reznichenko, Natalya, Tim Davies, James Shulmeister, and Mauri McSaveney. "Effects of debris on ice-surface melting rates: an experimental study." Journal of Glaciology 56, no. 197 (2010): 384–94. http://dx.doi.org/10.3189/002214310792447725.
Повний текст джерелаАнотація:
AbstractHere we report a laboratory study of the effects of debris thickness, diurnally cyclic radiation and rainfall on melt rates beneath rock-avalanche debris and sand (representing typical highly permeable supraglacial debris). Under continuous, steady-state radiation, sand cover >50 mm thick delays the onset of ice-surface melting by >12 hours, but subsequent melting matches melt rates of a bare ice surface. Only when diurnal cycles of radiation are imposed does the debris reduce the longterm rate of ice melt beneath it. This is because debris >50 mm thick never reaches a steady-state heat flux, and heat acquired during the light part of the cycle is partially dissipated to the atmosphere during the nocturnal part of the cycle, thereby continuously reducing total heat flux to the ice surface underneath. The thicker the debris, the greater this effect. Rain advects heat from high-permeability supraglacial debris to the ice surface, thereby increasing ablation where thin, highly porous material covers the ice. In contrast, low-permeability rock-avalanche material slows water percolation, and heat transfer through the debris can cease when interstitial water freezes during the cold/night part of the cycle. This frozen interstitial water blocks heat advection to the ice–debris contact during the warm/day part of the cycle, thereby reducing overall ablation. The presence of metre-deep rock-avalanche debris over much of the ablation zone of a glacier can significantly affect the mass balance, and thus the motion, of a glacier. The length and thermal intensity of the diurnal cycle are important controls on ablation, and thus both geographical location and altitude significantly affect the impact of debris on glacial melting rates; the effect of debris cover is magnified at high altitude and in lower latitudes.
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Schneider, D., C. Huggel, W. Haeberli, and R. Kaitna. "Unraveling driving factors for large rock-ice avalanche mobility." Earth Surface Processes and Landforms 36, no. 14 (October 21, 2011): 1948–66. http://dx.doi.org/10.1002/esp.2218.
Повний текст джерела
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Srivastava, Piyush, Prabhakar Namdev, and Praveen Kumar Singh. "7 February Chamoli (Uttarakhand, India) Rock-Ice Avalanche Disaster: Model-Simulated Prevailing Meteorological Conditions." Atmosphere 13, no. 2 (February 5, 2022): 267. http://dx.doi.org/10.3390/atmos13020267.
Повний текст джерелаАнотація:
The present study aims to analyze the high-resolution model-simulated meteorological conditions during the Chamoli rock-ice avalanche event, which occurred on 7 February 2021 in the Chamoli district of Uttarakhand, India (30.37° N, 79.73° E). The Weather Research and Forecasting (WRF) model is used to simulate the spatiotemporal distribution of meteorological variables pre- and post-event. The numerical simulations are carried out over two fine resolution nested model domains covering the Uttarakhand region over a period of 2 weeks (2 February to 13 February 2021). The model-simulated meteorological variables, e.g., air temperature, surface temperature, turbulent heat flux, radiative fluxes, heat and momentum transfer coefficients, specific humidity and upper wind patterns, were found to show significant departures from their usual patterns starting from 72 h until a few hours before the rock-ice avalanche event. The average 2 m air and surface temperatures near the avalanche site during the 48 h before the event were found to be much lower than the average temperatures post-event. In-situ observations and the ERA5-Land dataset also confirm these findings. The total turbulent heat flux mostly remained downward (negative) in the 72 h before the event and was found to have an exceptionally large negative value a few hours before the rock-ice avalanche event. The model-simulated rainfall and Global Precipitation Measurement (GPM, IMERG)-derived rainfall suggest that the part of the Himalayan region falling in the simulation domain received a significant amount of rainfall on 4 February, around 48 h prior to the event, while the rest of the days pre- and post-event were mostly dry. The results presented here might be helpful in further studies to identify the possible trigger factors of this event.
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Petersen, Eric Ivan, Joseph S. Levy, John W. Holt, and Cassie M. Stuurman. "New insights into ice accumulation at Galena Creek Rock Glacier from radar imaging of its internal structure." Journal of Glaciology 66, no. 255 (October 4, 2019): 1–10. http://dx.doi.org/10.1017/jog.2019.67.
Повний текст джерелаАнотація:
AbstractThe ice-cored Galena Creek Rock Glacier, Wyoming, USA, has been the subject of a number of studies that sought to determine the origin of its ice. We present new observations of the rock glacier's internal structure from ground-penetrating radar to constrain ice and debris distribution and accumulation. We imaged dipping reflectors in the center of the glacier that are weak and discontinuous, in contrast to strong reflectors toward the edge of the cirque beneath large debris-avalanche chutes. These reflectors form a network of concave-up, up-glacier dipping layers. We interpret these as englacial debris bands formed by large debris falls buried by subsequent ice and snow accumulation. They are discontinuous where ice outpaces debris accumulation, but with sufficient debris accumulation an interleaved pattern of ice and debris layers can form. We propose a model in which the ice in these interleaved layers is snowfall preserved by debris-facilitated accumulation. Large debris falls that occur in early spring bury sections of the snowpack, which are then preserved through summer and incorporated into the rock glacier body over time. This study highlights the importance of sequential accumulation of ice and debris for understanding the dynamics of rock glaciers and debris-covered glaciers.
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Zhao, Chuanxi, Wei Yang, Matthew Westoby, Baosheng An, Guangjian Wu, Weicai Wang, Zhongyan Wang, Yongjie Wang, and Stuart Dunning. "Brief communication: An approximately 50 Mm<sup>3</sup> ice-rock avalanche on 22 March 2021 in the Sedongpu valley, southeastern Tibetan Plateau." Cryosphere 16, no. 4 (April 12, 2022): 1333–40. http://dx.doi.org/10.5194/tc-16-1333-2022.
Повний текст джерелаАнотація:
Abstract. On 22 March 2021, an approximately 50 Mm3 ice-rock avalanche occurred from 6500 m a.s.l. in the Sedongpu basin, southeastern Tibet. The avalanche transformed into a highly mobile mass flow which temporarily blocked the Yarlung Tsangpo river. The avalanche flow lasted ∼ 5 min and produced substantial geomorphological reworking. This event, and previous ones from the basin, occurred concurrently with, or shortly after, positive seasonal air temperature anomalies. The occurrence of future large mass flows from the basin cannot be ruled out, and their impacts must be carefully considered given implications for sustainable hydropower and associated socioeconomic development in the region.
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Gilany, N., J. Iqbal, and E. Hussain. "Geospatial Analysis and Simulation of Glacial Avalanche Hazard in Hunza River Basin." International Journal of Environmental Science and Development 12, no. 2 (2021): 51–57. http://dx.doi.org/10.18178/ijesd.2021.12.2.1317.
Повний текст джерелаАнотація:
Glacial avalanche hazard poses threat to human lives and damage settlements / infrastructures in alpine glaciers mountainous regions. A gigantic ice plus rock avalanche destroyed Gyari military camp in Siachen sector on April 2012 and buried 139 personals. The study focuses on geospatial analysis and simulation of Shishper glacial avalanche of Hunza basin. To simulate the potential glacial avalanche hazard to Hassan Abad settlements, an empirical process based Glacier Avalanche Model; Rapid Access Mass Movement Simulation (RAMMS) is utilized. The model encompasses avalanche release area and height for the execution of simulation. The model output of Shishper glacial avalanche resulted; a max pressure of 450 Kpa, max velocity of 40 m/s, and the max flow height of 80m, while the resulted surge extent output was 2500m. The potential hazardous Shishper glacial avalanche remains a continuous hazard to Hassan Abad of Hunza valley including Karakoram Highway and Frontier Works Organization (FWO) camp. The study has resulted in identifying the Upper Indus Bain (UIB) being more prone to glacial avalanche hazards because of host factors in general and the anthropogenic factor in particular.
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Zaporozhchenko, E. V. "Ice-rock avalanche of 2002 in Genaldon River valley, North Caucasus, Russia: consequences and problems." Journal of Nepal Geological Society 34 (October 9, 2006): 99–108. http://dx.doi.org/10.3126/jngs.v34i0.31884.
Повний текст джерелаАнотація:
The biggest glacial disaster in the Russian history occurred in September 2002. A huge ice- rock-water flow from the Kolka Glacier went down the Genaldon River valley with a speed of 320 km/h. Having travelled a distance of 18.5 km, it was stopped by the 2 km long narrows of the Rocky Mountain Range and it filled the hollow with 120 ml of deposits. The ice rock-water mass pressed through the narrows forming a debris flow which went down the valley for 10 km devastating all the settlements on the riverbed. As a result, 125 people lost their lives. In 2002, two months before the disaster, a series of collapses from an elevation of about 1000 m at the backside of the glacier had activated the avalanche. The last ice- mass collapse had a volume of 10 million ml. The material accumulated in the glacier hollow was knocked off and went down the valley. The 100-150 m high ice- rock- water mass (with air also) was moving down the 400- 500 m wide valley. The flow on its way down the valley trough was fed by the frontal masses of three huge ancient landslides situated on the left bank. The hazards and risks after 2002 can be attributed mainly to the filling up of the hollow by the ice-rock material, the formation of a dammed lake, and the filling up of the narrows by debris flow and mudflow deposits. Presently the dammed lake is discharging naturally and there is about 0.5 million ml of water in it. The future behaviour of the ice-rock dam is not clear and it is difficult to make any forecast due to its melting on the one hand and the formation of underground outflows with sporadic floods on the other hand. In 2002-2004 the debris flow deposits on the riverbed were still unstable and loose. A surge with a discharge of more than 20 m3/sec and (or) a storm flood of such a magnitude can adversely affect the riverbed processes in the overpopulated foothill areas requiring mitigation and protective measures.
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Frauenfelder, Regula, Ketil Isaksen, Matthew J. Lato, and Jeannette Noetzli. "Ground thermal and geomechanical conditions in a permafrost-affected high-latitude rock avalanche site (Polvartinden, northern Norway)." Cryosphere 12, no. 4 (April 27, 2018): 1531–50. http://dx.doi.org/10.5194/tc-12-1531-2018.
Повний текст джерелаАнотація:
Abstract. On 26 June 2008, a rock avalanche detached in the northeast facing slope of Polvartinden, a high-alpine mountain in Signaldalen, northern Norway. Here, we report on the observed and modelled past and present near-surface temperature regime close to the failure zone, as well as on a subsequent simulation of the subsurface temperature regime, and on initial geomechanical mapping based on laser scanning. The volume of the rock avalanche was estimated to be approximately 500 000 m3. The depth to the actual failure surface was found to range from 40 m at the back of the failure zone to 0 m at its toe. Visible in situ ice was observed in the failure zone just after the rock avalanche. Between September 2009 and August 2013, ground surface temperatures were measured with miniature temperature data loggers at 14 different localities, close to the original failure zone along the northern ridge of Polvartinden and on the valley floor. The results from these measurements and from a basic three-dimensional heat conduction model suggest that the lower altitudinal limit of permafrost at present is at 600–650 m a.s.l., which corresponds to the upper limit of the failure zone. A coupling of our in situ data with regional climate data since 1958 suggests a general gradual warming and that the period with highest mean near surface temperatures on record ended four months before the Signaldalen rock avalanche detached. A comparison with a transient permafrost model run at 10 m depth, representative for areas where snow accumulates, strengthen these findings, which are also in congruence with measurements in nearby permafrost boreholes. It is likely that permafrost in and near the failure zone is presently subject to degradation. This degradation, in combination with the extreme warm year antecedent to the rock failure, is seen to have played an important role in the detaching of the Signaldalen rock avalanche.