scholarly journals Transferability of a calibrated numerical model of rock avalanche run-out: Application to 20 rock avalanches on the Nuussuaq Peninsula, West Greenland

2018 ◽  
Vol 43 (15) ◽  
pp. 3057-3073 ◽  
Author(s):  
J. Benjamin ◽  
N.J. Rosser ◽  
S.A. Dunning ◽  
R.J. Hardy ◽  
K. Kelfoun ◽  
...  
Keyword(s):  
Numerical Model ◽  
Rock Avalanche ◽  
West Greenland ◽  
Rock Avalanches

scholarly journals Evolution of events before and after the 17 June 2017 rock avalanche at Karrat Fjord, West Greenland – a multidisciplinary approach to detecting and locating unstable rock slopes in a remote Arctic area

2020 ◽  
Vol 8 (4) ◽  
pp. 1021-1038
Author(s):  
Kristian Svennevig ◽  
Trine Dahl-Jensen ◽  
Marie Keiding ◽  
John Peter Merryman Boncori ◽  
Tine B. Larsen ◽  
...  
Keyword(s):  
Multidisciplinary Approach ◽  
Rock Slope ◽  
Rock Avalanche ◽  
Rock Slopes ◽  
Slope Failures ◽  
West Greenland ◽  
Arctic Regions ◽  
Rock Avalanches ◽  
Dip Slope ◽  
Unstable Rock

Abstract. The 17 June 2017 rock avalanche in the Karrat Fjord, West Greenland, caused a tsunami that flooded the nearby village of Nuugaatsiaq and killed four people. The disaster was entirely unexpected since no previous records of large rock slope failures were known in the region, and it highlighted the need for better knowledge of potentially hazardous rock slopes in remote Arctic regions. The aim of the paper is to explore our ability to detect and locate unstable rock slopes in remote Arctic regions with difficult access. We test this by examining the case of the 17 June 2017 Karrat rock avalanche. The workflow we apply is based on a multidisciplinary analysis of freely available data comprising seismological records, Sentinel-1 spaceborne synthetic-aperture radar (SAR) data, and Landsat and Sentinel-2 optical satellite imagery, ground-truthed with limited fieldwork. Using this workflow enables us to reconstruct a timeline of rock slope failures on the coastal slope here collectively termed the Karrat Landslide Complex. Our analyses show that at least three recent rock avalanches occurred in the Karrat Landslide Complex: Karrat 2009, Karrat 2016, and Karrat 2017. The latter is the source of the abovementioned tsunami, whereas the first two are described here in detail for the first time. All three are interpreted as having initiated as dip-slope failures. In addition to the recent rock avalanches, older rock avalanche deposits are observed, demonstrating older (Holocene) periods of activity. Furthermore, three larger unstable rock slopes that may pose a future hazard are described. A number of non-tectonic seismic events confined to the area are interpreted as recording rock slope failures. The structural setting of the Karrat Landslide Complex, namely dip slope, is probably the main conditioning factor for the past and present activity, and, based on the temporal distribution of events in the area, we speculate that the possible trigger for rock slope failures is permafrost degradation caused by climate warming. The results of the present work highlight the benefits of a multidisciplinary approach, based on freely available data, to studying unstable rock slopes in remote Arctic areas under difficult logistical field conditions and demonstrate the importance of identifying minor precursor events to identify areas of future hazard.

scholarly journals Evolution of events before and after the 17 June 2017 landslide at Karrat, West Greenland – a multidisciplinary approach for studying landslides in a remote arctic area

2020 ◽  
Author(s):  
Kristian Svennevig ◽  
Trine Dahl-Jensen ◽  
Marie Keiding ◽  
John Peter Merryman Boncori ◽  
Tine B. Larsen ◽  
...  
Keyword(s):  
Multidisciplinary Approach ◽  
Rock Avalanche ◽  
Temporal Distribution ◽  
Permafrost Degradation ◽  
West Greenland ◽  
Landslide Activity ◽  
Rock Avalanches ◽  
Before And After ◽  
Arctic Area ◽  
First Time

Abstract. The 17 June 2017 rock avalanche on the south facing slope of the Ummiammakku Mountain (Karrat Isfjord, West Greenland) caused a tsunami that flooded the nearby village of Nuugaatsiaq, killed four persons and destroyed 11 buildings. Landslide activity in the area was not previously known and the disaster gave rise to important questions about what events led up to the landslide and what the future hazard is in the area around the landslide? However, the remoteness of the area and difficult fieldwork conditions, made it challenging to answer these questions. We apply a multidisciplinary workflow to reconstruct a timeline of events on the coastal slope here collectively termed the Karrat Landslide Complex. The workflow combines limited fieldwork with analyses of freely available remote sensed data comprising seismological records, Sentinel-1 space borne Synthetic Aperture Radar (SAR) data and Landsat and Sentinel-2 multispectral optical satellite imagery. Our analyses show that at least three historic rock avalanches occurred in the Karrat Landslide Complex: Karrat 2009, Karrat 2016 and Karrat 2017. The last is the source of the tsunami and the first two are described for the first time here. All three are interpreted to have initiated as translational rockslides. In addition to the historical rock avalanches, several pre historic rock avalanche deposits are observed, demonstrating older periods of activity. Furthermore, three larger areas of continuous activity are described and may pose a potential future hazard. A number of non-tectonic seismic events confined to the landslide complex are interpreted to record landslide activity. Based on the temporal distribution of events in the landslide complex, we speculate that the possible trigger for landslides is permafrost degradation caused by climate warming. The results of the present work highlight the benefits of a multidisciplinary approach based on freely available data to studying landslides in remote Arctic areas under difficult logistical field conditions and demonstrates the importance of identifying minor precursor events to identify areas of future hazard.

Recurrent rock avalanches progressively dismantle mountain ridges in the Longmen Shan, China, most recently in the 2008 Wenchuan earthquake

2021 ◽  
Author(s):  
Janusz Wasowski ◽  
Maurice McSaveney ◽  
Luca Pisanu ◽  
Vincenzo Del Gaudio ◽  
Yan Li ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Ambient Noise ◽  
Slope Failure ◽  
Mass Movement ◽  
Rock Avalanche ◽  
Ground Vibration ◽  
Source Area ◽  
Slope Failures ◽  
Rock Avalanches ◽  
Beichuan County

<p>Large earthquake-triggered landslides, in particular rock avalanches, can have catastrophic consequences. However, the recognition of slopes prone to such failures remains difficult, because slope-specific seismic response depends on many factors including local topography, landforms, structure and internal geology. We address these issues by exploring the case of a rock avalanche of >3 million m<sup>3</sup> triggered by the 2008 Mw7.9 Wenchuan earthquake in the Longmen Shan range, China. The failure, denominated Yangjia gully rock avalanche, occurred in Beichuan County (Sichuan Province), one of the areas that suffered the highest shaking intensity and death toll caused by co-seismic landsliding. Even though the Wenchuan earthquake produced tens of large (volume >1 million m<sup>3</sup>) rock avalanches, few studies so far have examined the pre-2008 history of the failed slope or reported on the stratigraphic record of mass-movement deposits exposed along local river courses. The presented case of the Yangjia gully rock avalanche shows the importance of such attempts as they provide information on the recurrence of large slope failures and their associated hazards. Our effort stems from recognition, on 2005 satellite imagery, of topography and morphology indicative of a large, apparently pre-historic slope failure and the associated breached landslide dam, both features closely resembling the forms generated in the catastrophic 2008 earthquake. The follow-up reconstruction recognizes an earlier landslide deposit exhumed from beneath the 2008 Yangjia gully rock avalanche by fluvial erosion since May 2008. We infer a seismic trigger also for the pre-2008 rock avalanche based on the following circumstantial evidence: i) the same source area (valley-facing, terminal portion of a flat-topped, elongated mountain ridge) located within one and a half kilometer of the seismically active Beichuan fault; ii) significant directional amplification of ground vibration, sub-parallel to the failed slope direction, detected via ambient noise measurements on the ridge adjacent to the source area of the 2008 rock avalanche and iii) common depositional and textural features of the two landslide deposits. Then, we show how, through consideration of the broader geomorphic and seismo-tectonic contexts, one can gain insight into the spatial and temporal recurrence of catastrophic slope failures  in Beichuan County and elsewhere in the Longmen Shan. This insight, combined with local-scale geologic and geomorphologic knowledge, may guide selection of suspect slopes for reconnaissance, wide-area ambient noise investigation aimed at discriminating their relative susceptibility to co-seismic catastrophic failures. We indicate the feasibility of such investigations through the example of this study, which uses 3-component velocimeters designed to register low amplitude ground vibration.</p>

Emplacement dynamics of supraglacial rock avalanches: details from the 2016 Lamplugh event, Alaska

2020 ◽  
Author(s):  
Anja Dufresne ◽  
Gabriel Wolken ◽  
Clément Hibert ◽  
Erin Bessette-Kirton ◽  
Jeffrey Coe ◽  
...  
Keyword(s):  
Seismic Data ◽  
Granular Flow ◽  
Rock Avalanche ◽  
Strong Interactions ◽  
Low Friction ◽  
Field Surveys ◽  
Glacier Bay ◽  
Rock Avalanches ◽  
Digital Elevation ◽  
Stage 1

<p>In Glacier Bay Park and Preserve, Alaska, at least 25 rock avalanches occurred since the mid-1980s. The 2016 Lamplugh rock avalanche, with roughly 70 Mm<sup>3 </sup>deposit volume, is one of the larger events within the park. It originated from a north-facing bedrock ridge without any obvious trigger, and spread 10 km down Lamplugh Glacier. Based on field surveys, high-resolution digital elevation models, and continuous seismic data, we show that the emplacement dynamics of this supraglacial rock avalanche can be described by two distinct stages. Clear long-period seismic signals during Stage-1 record strong interactions of the rock avalanche debris with the ground, suggesting dynamic processes such as grain collisions and fragmentation ('active or dynamic emplacement' of a granular flow). During this first stage, the debris traveled about 5 km from the base of the slope; its deposit is thin and stretched with a dominant dry and flat area in the center, and has narrow raised margins. Stage-2 was essentially aseismic at long periods and dominated by low-friction sliding at slow deceleration rates ('passive sliding'). This sliding produced the distal roughly third of the total runout length where the deposit has a higher density of flowbands and more prominent, raised margins from entrainment and bulldozing of snow. The higher apparent mobility of supraglacial landslides (relative to their counterparts in other runout environments) may be explained by this two-stage model.</p>

The 1513 Monte Crenone Rock Avalanche. Numerical model and geomorphological analysis

2020 ◽  
Author(s):  
Alessandro De Pedrini ◽  
Christian Ambrosi ◽  
Cristian Scapozza
Keyword(s):  
Numerical Model ◽  
Mass Movement ◽  
Rock Avalanche ◽  
Digital Data ◽  
Western Slope ◽  
Deposition Zone ◽  
Federal Institute ◽  
Landslide Body ◽  
The Alps ◽  
Movement Simulation

<p>The Monte Crenone rock avalanche of 30 September 1513 is one of the most catastrophic natural events in Switzerland and throughout the Alps. The enormous mass of rock that broke away from the western slope of Pizzo Magn or Monte Crenone, estimated at 50-90 million cubic metres, caused the complete damming of the course of the Brenno river, leading to the formation of a basin that extended from Biasca to the Castello di Serravalle in Semione (De Antoni et al. 2016). On 20 May 1515 the basin formed behind the dam overflowed, giving rise to a wave of more than 10 meters high that led to devastation in the territories downstream to reach Lake Maggiore (Scapozza et al. 2015).</p><p>In this project, we analyze the dynamics of the 1513 rock avalanche, trying to reconstruct the event through a numerical model, calculated with the software RAMMS::Debrisflow (RApid Mass Movement Simulation) provided by the Federal Institute for the Study of Snow and Avalanches (SLF/WSL).</p><p>The realization of the numerical model was preceded by the reconstruction of the topography before the landslide. This first phase of work, included a geological survey of the landslide body, the analysis of digital data (orthophotos, digital topographic maps, shaded model derived from swissALTI3D) and the collection of previous historical data.</p><p>The observation of the stratigraphic data obtained from the 701.27, 701.30 and 701.31 boreholes (part of the geotechnical studies for the Chiasso-San Gottardo highway) of the GESPOS database (GEstione Sondaggi, POzzi e Sorgenti) of the Institute of Earth Sciences SUPSI was essential to understand the landslide body thickness and volume in the deposition zone.</p><p>From the first phase of data collection and interpretation, we then moved on to the actual reconstruction of the digital model of the terrain before the landslide. This operation was carried out using ESRI's ArcGIS software, which made it possible recreating multiple models of the pre-event topography and thus finding the most realistic solution applicable to the subsequent RAMMS model.</p>

Dynamic analysis of an extraordinarily mobile rock avalanche in the Northwest Territories, Canada

2016 ◽  
Vol 53 (6) ◽  
pp. 899-908 ◽  
Author(s):  
Jordan Aaron ◽  
Oldrich Hungr
Keyword(s):  
Sensitivity Analysis ◽  
Natural Disaster ◽  
Hazard Analysis ◽  
Three Dimensional ◽  
Rock Avalanche ◽  
Friction Angle ◽  
Source Zone ◽  
Glacial Ice ◽  
Rock Avalanches ◽  
Landslide Runout

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.

Rock Avalanches

2018 ◽  
Author(s):  
Tim Davies
Keyword(s):  
Rock Avalanche ◽  
Long Runout ◽  
Runout Distance ◽  
Glacier Terminus ◽  
Rock Avalanches ◽  
Landslide Volume ◽  
Long Duration ◽  
Wide Range ◽  
The 19Th Century ◽  
Scientific Questions

Rock avalanches are very large (greater than about 1 million m3) landslides from rock slopes, which can travel much farther than smaller events; the larger the avalanche, the greater the travel distance. Rock avalanches first became recognized in Switzerland in the 19th century, when the Elm and Goldau events killed many people a surprisingly long way from the origin of the landslide; these events first posed the “long-runout rock-avalanche” problem. In essence, the several-kilometer-long runout of these events appears to require low friction beneath and within the moving rock mass in order to explain their extremely long deposits, but in spite of intense research in recent decades this phenomenon still lacks a generally accepted explanation. Large collapses of volcano edifices can also generate rock avalanches that travel very long distances, albeit with a different runout–volume relationship to that of non-volcanic events. Even more intriguing is the presence of long-runout deposits not just on land but also beneath the sea and on the surfaces of Mars and the Moon. Numerous studies of rock avalanches have revealed a number of consistencies in deposit and behavioral characteristics: for example, that little or no mixing of material occurs within the moving debris mass during runout; that the deposit material beneath a meter-scale surface layer is pervasively and intensely fragmented, with fragments down to submicrometer size; that many of these fragments are agglomerates of even finer particles; that throughout the travel of a rock avalanche large volumes of fine dust are produced; that rock avalanche surfaces are typically covered by hummocks of a range of sizes; and that, as noted above, runout distance increases with volume. Since rock avalanches can travel tens of kilometers from their source, they pose severe, if low-probability, direct hazards to societal assets in mountain valleys; in addition, they can trigger extensive and long-duration geomorphic hazard cascades. Although large rock avalanches are rare (e.g., in a 10,000 km2 area of the Southern Alps in New Zealand, research showed that events larger than 5 × 107 m3 occurred about once every century), studies to date show that the proportion of total landslide volume involved in such large events is greater than the proportion in smaller, more frequent events, so that a large proportion of the total sediment generated in mountains by uplift and denudation originates in large rock avalanches. Consequently, large rock avalanches exert a significant influence on mountain geomorphology, for example by blocking rivers and forming landslide dams; these either fail, causing large dam-break floods and long-duration aggradation episodes to propagate down river systems, or remain intact to infill with sediment and form large valley flats. Rock avalanches that fall onto glaciers often result in large terminal moraines being formed as debris accumulates at the glacier terminus, and these moraines may have no relation to any climatic change. In addition, misinterpretation of rock avalanche deposits as moraines can cause underestimation of hazard risk and misinterpretation of paleoclimate. Rock avalanche runout behavior poses fundamental scientific questions, and rock avalanches have important effects on a wide range of geomorphic processes, which in turn pose threats to society. Better understanding of these impressive and intriguing events is crucial for both geoscientific progress and for reducing impacts of future disasters.

scholarly journals A cautionary note for rock avalanche field investigation – recent sequential and overlapping landslides in British Columbia

2020 ◽  
Author(s):  
Marten Geertsema ◽  
Alexandre Bevington
Keyword(s):  
British Columbia ◽  
Satellite Remote Sensing ◽  
Rock Avalanche ◽  
Field Investigation ◽  
Western North America ◽  
Cautionary Note ◽  
Rock Avalanches ◽  
Site Field ◽  
Fresh Rock ◽  
Sentinel 2

Large rock avalanches on glaciers are an annual occurrence in the mountains of western North America. Following an event, landslide investigators may strive to quickly arrive on site to assess the deposit. Satellite remote sensing imagery demonstrates that caution is warranted for on- site field assessments. We combine Landsat, Sentinel-1(radar), Sentinel-2 and Planet imagery to reconstruct the events of four recent double overlapping rock avalanche deposits in British Columbia. In our examples substantial precursory rock avalanches are closely followed (days - months) and buried by much larger landslides. We suggest that landslide investigators exercise caution when assessing fresh rock avalanches avalanche deposits in the field.

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