scholarly journals Impact of an 0.2 km 3 Rock Avalanche on Lake Eibsee (Bavarian Alps, Germany) – Part II: Catchment Response to Consecutive Debris Avalanche and Debris Flow

2020 ◽  
Author(s):  
Sibylle Knapp ◽  
Flavio S. Anselmetti ◽  
Bernhard Lempe ◽  
Michael Krautblatter
Keyword(s):  
Debris Flow ◽  
Rock Avalanche ◽  
Debris Avalanche ◽  
Bavarian Alps

Extreme mass wasting during 2021 Dhauli Ganga event in the Higher Himalaya: insight from the landscape

2021 ◽  
Author(s):  
Anand Kumar Pandey ◽  
Kotluri Sravan Kumar ◽  
Virendra Mani Tiwari ◽  
Puranchand Rao ◽  
Kirsten Cook ◽  
...  
Keyword(s):  
Debris Flow ◽  
Extreme Event ◽  
Rock Avalanche ◽  
Slope Instability ◽  
Mass Wasting ◽  
Outburst Flood ◽  
Flood Warning ◽  
River Bed ◽  
High Flood ◽  
Glacial Lake Outburst Flood

<p>The slope instability and associated mass wasting are among the most efficient surface gradation processes in the bedrock terrain that produce dramatic landscape change and associated hazards. The wedge failure in periglacial Higher Himalaya terrain on 7th February in Chamoli, Uttarakhand (India) produced >1.5 km high rock avalanche, which amalgamated with the glacial debris on the frozen river bed produced massive debris flow along the high gradient Rishi Ganga catchment. The high-velocity debris flow and a surge of high flood led to extensive loss of life and infrastructures and issuing the extreme event flood warning along the Alakananda-Ganga river, despite there was no immediate extreme climatic event. The affected region is the locus of extreme mass wasting events associated with Glacial Lake Outburst Flood (GLOF) and Landslide Lake Outburst Flood (LLOF) in the recent past. We analyzed the landscape to understand its control on the 7th February 2021 Rishi Ganga event and briefly discuss other significant events in the adjoining region e.g. 1893/1970 Gohna Tal/Lake LLOF and 2013-Uttarakhand events in Chamoli, which have significance in understanding the surface processes in Higher Himalayan terrain.</p>

scholarly journals Back-calculation of the 2017 Piz Cengalo-Bondo landslide cascade with r.avaflow

2019 ◽  
Author(s):  
Martin Mergili ◽  
Michel Jaboyedoff ◽  
José Pullarello ◽  
Shiva P. Pudasaini
Keyword(s):  
Debris Flow ◽  
Flow Model ◽  
Rock Avalanche ◽  
Simulation Software ◽  
Process Models ◽  
Rock Fall ◽  
Model Parameters ◽  
Rock Slide ◽  
Glacier Ice ◽  
Initial Rock

Abstract. In the morning of 23 August 2017, around 3 million m3 of granitoid rock broke off from the east face of Piz Cengalo, SE Switzerland. The initial rock slide-rock fall entrained 0.6 million m3 of a glacier and continued as a 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 rock slide-rock fall 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 rock slide-rock fall 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/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 be numerically reproduced with the two-phase mass flow model implemented with the simulation software r.avaflow, based on plausible assumptions of the model parameters. However, these simulation results do not allow 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, 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.

scholarly journals Observations on the May 2019 Joffre Peak landslides, British Columbia

Landslides ◽  
2020 ◽  
Vol 17 (4) ◽  
pp. 913-930 ◽  
Author(s):  
Pierre Friele ◽  
Tom H. Millard ◽  
Andrew Mitchell ◽  
Kate E. Allstadt ◽  
Brian Menounos ◽  
...  
Keyword(s):  
British Columbia ◽  
Debris Flow ◽  
Seismic Analysis ◽  
Rock Avalanche ◽  
Permafrost Degradation ◽  
Depth Estimate ◽  
Coast Mountains ◽  
Conditioning Factors ◽  
The North ◽  
Debris Flood

AbstractTwo catastrophic landslides occurred in quick succession on 13 and 16 May 2019, from the north face of Joffre Peak, Cerise Creek, southern Coast Mountains, British Columbia. With headscarps at 2560 m and 2690 m elevation, both began as rock avalanches, rapidly transforming into debris flows along middle Cerise Creek, and finally into debris floods affecting the fan. Beyond the fan margin, a flood surge on Cayoosh Creek reached bankfull and attenuated rapidly downstream; only fine sediment reached Duffey Lake. The toe of the main debris flow deposit reached 4 km from the headscarp, with a travel angle of 0.28, while the debris flood phase reached the fan margin 5.9 km downstream, with a travel angle of 0.22. Photogrammetry indicates the source volume of each event is 2–3 Mm3, with combined volume of 5 Mm3. Lidar differencing, used to assess deposit volume, yielded a similar total result, although error in the depth estimate introduced large volume error masking the expected increase due to dilation and entrainment. The average velocity of the rock avalanche-debris flow phases, from seismic analysis, was ~ 25–30 m/s, and the velocity of the 16 May debris flood on the upper fan, from super-elevation and boulder sizes, was 5–10 m/s. The volume of debris deposited on the fan was ~ 104 m3, 2 orders of magnitude less than the avalanche/debris flow phases. Progressive glacier retreat and permafrost degradation were likely the conditioning factors; precursor rockfall activity was noted at least ~6 months previous; thus, the mountain was primed to fail. The 13 May landslide was apparently triggered by rapid snowmelt, with debuttressing triggering the 16 May event.

Three-Dimensional Numerical Analysis of a Potential Rock Avalanche by Discrete Element Method

2020 ◽  
Vol 12 (2) ◽  
pp. 225-231
Author(s):  
Chuan Zhao ◽  
Linlin Jiang ◽  
Xiaopeng Li ◽  
Xiangyu Guo ◽  
Xiang Xiao
Keyword(s):  
Discrete Element Method ◽  
Average Velocity ◽  
Three Dimensional ◽  
Rock Avalanche ◽  
Discrete Element ◽  
Debris Avalanche ◽  
The Other ◽  
Strength Model ◽  
Whole Process ◽  
Element Method

In the present paper, the aim is at studying the kinematic process and deposit geometry of a potential rock avalanche in Italy. The rock fragmentation and the effect of different bonding strengths are evaluated. To simulate the sliding and destruction of the potential rock avalanche, a 3D discrete element software EDEM is employed. The results suggest that a dam will be formed nearly 70 sec after the avalanche occurs, and the maximum average velocity of the avalanche reaches over 40 m/s. The whole process can be split into 4 stages (instability, acceleration, fast sliding and decelerate deposition). There are three possible paths for debris to slide. The major path located in the middle, and the other 2 only have few rock debris. Furthermore, small bonding strength model of the discrete element method (DEM) applies to the simulation of the potential rock avalanche disasters, allowing the sliding in a form of debris avalanche with good liquidity.

A review of the classification of landslides of the flow type

2001 ◽  
Vol 7 (3) ◽  
pp. 221-238 ◽  
Author(s):  
Oldrich Hungr ◽  
S. G. Evans ◽  
M. J. Bovis ◽  
J. N. Hutchinson
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Large Scale ◽  
Debris Avalanche ◽  
Basic Material ◽  
Morphological Aspects ◽  
Flow Slides ◽  
Size Limits ◽  
Plastic Clays ◽  
Earth Flows

Abstract As a result of the widespread use of the landslide classifications of Varnes (1978), and Hutchinson (1988), certain terms describing common types of flow-like mass movements have become entrenched in the language of engineering geology. Example terms include debris flow, debris avalanche and mudslide. Here, more precise definitions of the terms are proposed, which would allow the terms to be retained with their original meanings while making their application less ambiguous. A new division of landslide materials is proposed, based on genetic and morphological aspects rather than arbitrary grain-size limits. The basic material groups include sorted materials: gravel, sand, silt, and clay, unsorted materials: debris, earth and mud, peat and rock. Definitions are proposed for relatively slow non-liquefied sand or gravel flows, extremely rapid sand, silt or debris flow slides accompanied by liquefaction, clay flow slides involving extra-sensitive clays, peat flows, slow to rapid earth flows in nonsensitive plastic clays, debris flows which occur in steep established channels or gullies, mud flows considered as cohesive debris flows, debris floods involving massive sediment transport at limited discharges, debris avalanches which occur on open hill slopes and rock avalanches formed by large scale failures of bedrock.

Reconstruction constraints on the Estero Parraguirre ice-rock avalanche in 1987, Central Andes of Chile: New insights from remote sensing and numerical modeling.  

2021 ◽  
Author(s):  
Thomas Bruckner ◽  
David Farías-Barahona ◽  
Johannes Fürst ◽  
Martin Mergili ◽  
Sergio Sepulveda ◽  
...  
Keyword(s):  
Debris Flow ◽  
Power Plants ◽  
Rock Avalanche ◽  
Central Andes ◽  
High Elevation ◽  
Mitigation Strategies ◽  
Aerial Photographs ◽  
Hydroelectric Power ◽  
Physically Based ◽  
Mass Displacement

<p> On 29th of November of 1987, a large ice-rock avalanche occurred in a permafrost area of the central Andes of Chile. This event has been considered one of the most destructive events in that area in the last decades. The ice-rock avalanche initiated at an elevation of 4350 m, above the Estero Parraguirre. Due to the large amounts of ice and snow and the high potential energy, this avalanche developed into a debris flow propagating down the valley, reaching a travel distance of approx. 57 km after 2 hours. On the way, many people lost their lives, and two hydroelectric power plants were destroyed. The avalanche was likely triggered by warm temperature anomalies and snow build-up at high elevation linked to the concurrent and strong El Nino event in 1987.</p><p>In this study, we use old topographic maps and aerial photographs, acquired just a few days after the event, and satellite imagery to constrain the trigger volume and to accurately compute the general mass displacement. A physically-based multi-phase mass flow model is employed to retrace the dynamics and characteristics of this debris-flow event. Previous studies suggested a trigger volume of about 6 x 10<sup>6</sup> m<sup>3</sup>. After entrainment along the flow path, the debris flow reached a total volume of 15 x 10<sup>6</sup> m<sup>3</sup>. First results of our study suggest that the trigger volume was significantly larger than previously thought. The next step is to shed light on possible entrainment scenarios, which will be constrained by and assessed against the observed elevation changes/mass displacement.</p><p>The reconstruction of this event is crucial to better assess future events and thus to develop successful mitigation strategies.</p>

scholarly journals The 6 August 2010 Mount Meager rock slide-debris flow, Coast Mountains, British Columbia: characteristics, dynamics, and implications for hazard and risk assessment

2012 ◽  
Vol 12 (5) ◽  
pp. 1277-1294 ◽  
Author(s):  
R. H. Guthrie ◽  
P. Friele ◽  
K. Allstadt ◽  
N. Roberts ◽  
S. G. Evans ◽  
...  
Keyword(s):  
British Columbia ◽  
Debris Flow ◽  
Large Scale ◽  
Rock Avalanche ◽  
Volcanic Complex ◽  
Rock Slide ◽  
Night Time ◽  
Coast Mountains ◽  
Creek Watershed ◽  
The Impact

Abstract. A large rock avalanche occurred at 03:27:30 PDT, 6 August 2010, in the Mount Meager Volcanic Complex southwest British Columbia. The landslide initiated as a rock slide in Pleistocene rhyodacitic volcanic rock with the collapse of the secondary peak of Mount Meager. The detached rock mass impacted the volcano's weathered and saturated flanks, creating a visible seismic signature on nearby seismographs. Undrained loading of the sloping flank caused the immediate and extremely rapid evacuation of the entire flank with a strong horizontal force, as the rock slide transformed into a debris flow. The disintegrating mass travelled down Capricorn Creek at an average velocity of 64 m s−1, exhibiting dramatic super-elevation in bends to the intersection of Meager Creek, 7.8 km from the source. At Meager Creek the debris impacted the south side of Meager valley, causing a runup of 270 m above the valley floor and the deflection of the landslide debris both upstream (for 3.7 km) and downstream into the Lillooet River valley (for 4.9 km), where it blocked the Lillooet River river for a couple of hours, approximately 10 km from the landslide source. Deposition at the Capricorn–Meager confluence also dammed Meager Creek for about 19 h creating a lake 1.5 km long. The overtopping of the dam and the predicted outburst flood was the basis for a night time evacuation of 1500 residents in the town of Pemberton, 65 km downstream. High-resolution GeoEye satellite imagery obtained on 16 October 2010 was used to create a post-event digital elevation model. Comparing pre- and post-event topography we estimate the volume of the initial displaced mass from the flank of Mount Meager to be 48.5 × 106 m3, the height of the path (H) to be 2183 m and the total length of the path (L) to be 12.7 km. This yields H/L = 0.172 and a fahrböschung (travel angle) of 9.75°. The movement was recorded on seismographs in British Columbia and Washington State with the initial impact, the debris flow travelling through bends in Capricorn Creek, and the impact with Meager Creek are all evident on a number of seismograms. The landslide had a seismic trace equivalent to a M = 2.6 earthquake. Velocities and dynamics of the movement were simulated using DAN-W. The 2010 event is the third major landslide in the Capricorn Creek watershed since 1998 and the fifth large-scale mass flow in the Meager Creek watershed since 1930. No lives were lost in the event, but despite its relatively remote location direct costs of the 2010 landslide are estimated to be in the order of $10 M CAD.

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