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Research on the scraping effects of rock–ice avalanches remains relatively limited. This study investigates the evolution of rock–ice avalanches with varying ice content and initial accumulation forms during motion, scraping, and deposition using laboratory physical model experiments. Changes in pre- scraping velocity, scraping length, scraping depth, maximum deposition length, and deposition thickness were analyzed as functions of ice content. The analysis revealed the influence of ice content and initial accumulation on scraping effects, as well as on motion and deposition characteristics. The experimental results indicate that, compared to typical debris flows (without ice), the presence of ice significantly enhances the mobility, deposition features, and scraping effects of rock–ice avalanches. Through analysis, it is shown that the low friction of ice debris enhances the kinetic energy of ice-rock debris flows, thereby increasing the energy required for scraping. [ABSTRACT FROM AUTHOR]

Populations and infrastructure in high mountain regions are exposed to a wide range of natural hazards, the frequency, magnitude, and location of which are extremely sensitive to climate change. In cases where several hazards can occur simultaneously or where the occurrence of one event will change the disposition of another, assessments need to account for complex process chains. While process chains are widely recognized as a major threat, no systematic analysis has hitherto been undertaken. We therefore establish new understanding on the factors that directly trigger or alter the disposition for subsequent events in the chain and derive a novel classification scheme and parameters to aid natural hazard assessment. Process chains in high mountains are commonly associated with glacier retreat or permafrost degradation. Regional differences exist in the nature and rate of sequencing—some process chains are almost instantaneous, while other linkages are delayed. Process chains involving rapid sequences are difficult to predict, and impacts are often devastating. We demonstrate that process chains are triggered most frequently by progressive failures, being the result of gradual landscape weakening and not due to the occurrence of a distinct process. If fluvial processes are part of the process chain the reach (or mobility) of process chains is increased. Increased mobility can also occur if sediment deposition areas along river channels are activated. As climate changes causes glacial environments to transform into sediment‐rich paraglacial and fluvial landscapes, it is expected that the mobility of process chains will increase in the future. Plain Language Summary: Communities and their infrastructure located in mountain regions of the world are particularly susceptible to natural hazards, such as floods and landslides. While these events on their own can be bad enough, when such events occur at the same time or cause a chain‐reaction of different processes, consequences can be worse and extend far downstream. In view of this, we have undertaken a first comprehensive review of 51 relevant events occurring across different mountain regions globally to better understand how these process chains develop, and to identify which conditions increase the likelihood and or size of these events. A key finding is that process chains most frequently begin as the result of a mountain slope gradually becoming unstable over time, and in these cases, no other trigger such as an earthquake or unusually wet or hot weather are necessary. Far‐reaching process chains occur when rivers are involved and when additional gravel and debris sources are added to the mix. As a consequence of climate warming, icy mountain landscapes are thawing and become more unstable, increasing the risk of such process chains in the future. Key Points: High mountain hazard process chains commonly are associated with glacier retreat or permafrost degradationProcess chains are triggered most frequently by progressive failure, which is a result of long‐lasting landscape weakeningAn important implication of climate change is that we can expect an increase in the reach (horizontal length along the flow path) of process chain events in the future [ABSTRACT FROM AUTHOR]

A modelling approach to understand the tsunamigenic potentiality of submarine landslides will provide new perspectives on tsunami hazard threat, mostly in polar margins where global climatic change and its related ocean warming may induce future landslides. Here, we use the L-ML-HySEA (Landslide Multilayer Hyperbolic Systems and Efficient Algorithms) numerical model, including wave dispersion, to provide new insights into factors controlling the tsunami characteristics triggered by the Storfjorden LS-1 landslide (southwestern Svalbard). Tsunami waves, determined mainly by the sliding mechanism and the bathymetry, consist of two initial wave dipoles, with troughs to the northeast (Spitsbergen and towards the continent) and crests to the south (seawards) and southwest (Bear Island), reaching more than 3 m of amplitude above the landslide and finally merging into a single wave dipole. The tsunami wave propagation and its coastal impact are governed by the Storfjorden and Kveithola glacial troughs and by the bordering Spitsbergen Bank, which shape the continental shelf. This local bathymetry controls the direction of propagation with a crescent shape front, in plan view, and is responsible for shoaling effects of amplitude values (4.2 m in trough to 4.3 m in crest), amplification (3.7 m in trough to 4 m in crest) and diffraction of the tsunami waves, as well as influencing their coastal impact times. [ABSTRACT FROM AUTHOR]

The Luchedu rock avalanche (LRA) that occurred in 1935 at the junction of Sichuan and Yunnan in Southwest China is a disaster chain of the rock slide, debris avalanche, and river blocking induced by heavy rainfall. The rock slide originated from the wedge formed by sheet metamorphic rocks on the fault zone on the left bank of the Jinsha River. After breaking away from the slope, the wedge disintegrated and cracked rapidly, forming debris and causing them to flow in fluidization along a 7.3 km path. After the obvious entrainment process and curve superelevation in the proximal area, the deposition reached 50.5 × 10 6 m3 in the distal area. The sedimentary structure of clasts has typical stratification characteristics. The types of sedimentary facies include carapace facies, body facies, and mixed facies. Inside the sedimentary structure, dense shear zones, liquefied intercalations, jigsaw structures, and directional arrangement of particles are observed. Through a detailed geological survey and DEM spatial analysis, the avalanche entrainment rate of LRA was determined as 1.2. The morphological fluctuation of basement lithology and gully path plays an important role in the long-distance movement. The rock fragments formed by metamorphic rocks with a primary schistosity structure can effectively reduce the energy loss in the internal shear process and significantly promote the laminar flow movement in the distal region of the avalanche. Therefore, as a giant rock avalanche formed by the evolution of specific metamorphic rocks, LRA results from the combination of macrohydrodynamics and microrock failure properties. [ABSTRACT FROM AUTHOR]

Proper knowledge of velocity is required in accurately determining the enormous destructive energy carried by a landslide. We present the first, simple and physics-based general analytical landslide velocity model that simultaneously incorporates the internal deformation (nonlinear advection) and externally applied forces, consisting of the net driving force and the viscous resistant. From the physical point of view, the model represents a novel class of nonlinear advective–dissipative system, where classical Voellmy and inviscid Burgers' equations are specifications of this general model. We show that the nonlinear advection and external forcing fundamentally regulate the state of motion and deformation, which substantially enhances our understanding of the velocity of a coherently deforming landslide. Since analytical solutions provide the fastest, most cost-effective, and best rigorous answer to the problem, we construct several new and general exact analytical solutions. These solutions cover the wider spectrum of landslide velocity and directly reduce to the mass point motion. New solutions bridge the existing gap between negligibly deforming and geometrically massively deforming landslides through their internal deformations. This provides a novel, rapid, and consistent method for efficient coupling of different types of mass transports. The mechanism of landslide advection, stretching, and approaching the steady state has been explained. We reveal the fact that shifting, uplifting, and stretching of the velocity field stem from the forcing and nonlinear advection. The intrinsic mechanism of our solution describes the fascinating breaking wave and emergence of landslide folding. This happens collectively as the solution system simultaneously introduces downslope propagation of the domain, velocity uplift, and nonlinear advection. We disclose the fact that the domain translation and stretching solely depend on the net driving force, and along with advection, the viscous drag fully controls the shock wave generation, wave breaking, folding, and also the velocity magnitude. This demonstrates that landslide dynamics are architectured by advection and reigned by the system forcing. The analytically obtained velocities are close to observed values in natural events. These solutions constitute a new foundation of landslide velocity in solving technical problems. This provides practitioners with key information for instantly and accurately estimating the impact force that is very important in delineating hazard zones and for the mitigation of landslide hazards. [ABSTRACT FROM AUTHOR]

We describe and model the evolution of a recent landslide, tsunami, outburst flood, and sediment plume in the southern Coast Mountains, British Columbia, Canada. On November 28, 2020, about 18 million m3 of rock descended 1,000 m from a steep valley wall and traveled across the toe of a glacier before entering a 0.6 km2 glacier lake and producing >100‐m high run‐up. Water overtopped the lake outlet and scoured a 10‐km long channel before depositing debris on a 2‐km2 fan below the lake outlet. Floodwater, organic debris, and fine sediment entered a fjord where it produced a 60+km long sediment plume and altered turbidity, water temperature, and water chemistry for weeks. The outburst flood destroyed forest and salmon spawning habitat. Physically based models of the landslide, tsunami, and flood provide real‐time simulations of the event and can improve understanding of similar hazard cascades and the risk they pose. Plain Language Summary: Glacier retreat exposes unstable slopes that can suddenly fail. We describe and model one such event with far‐reaching consequences. The landslide mass (50 million tonnes, equivalent to the combined mass of all Canadian automobiles) entered and suddenly drained a 0.6‐km2 alpine lake in the southern Coast Mountains of British Columbia. Displaced water destroyed salmon‐spawning habitat over a distance of 8.5 km and created a plume of sediment and organic matter more than 60 km from the head of the fjord into which the floodwaters discharged. Physically based models are able to simulate the hazard cascade, and such models could be used to improve hazard and risk assessments of these events under future climate change. Key Points: Rapid glacier retreat created conditions that allowed a geohazard cascade to occur in a steep mountain valleyWe describe and model a recent landslide, tsunami, and outburst flood that typifies a deglacial geohazard cascadeFuture work should predict new glacial lakes and use physically based models to simulate the slope, tsunami, and outburst flood hazards [ABSTRACT FROM AUTHOR]

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 m 3. 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. [ABSTRACT FROM AUTHOR]

The present research was conducted to examine the relationship between goal orientation, motivation, and competitive anxiety in players of domestic cricket in Pakistan. The sample comprised of 105 male domestic cricketers aged between 18 to 35 years (M = 20.02, SD = 2.75). Correlational research design and purposive sampling strategy was used to draw sample from different cricket clubs and academies in Lahore and the permission to collect data was taken from the authorities of Pakistan Cricket Board. Task and Ego Orientation in Sport Questionnaire (Duda & Nicholls, 1992), Sport Motivation Scale-II (Pelletier, Rocchi, Vallerand, Deci, & Ryan, 2013), Sport Anxiety Scale-2 (Smith, Smoll, Cumming, & Grossbard, 2006), Beliefs About the Causes of Sport Success Questionnaire (Duda & Nicholls, 1992) and Multidimensional Inventory of Perfectionism in Sport (Stober, Otto, & Stoll, 2006) were administered to the participants. Pearson product moment correlation revealed that ego orientation was positively correlated with external regulation, whereas task orientation was positively correlated with intrinsic regulation. Also, intrinsic regulation was negatively correlated with competitive anxiety. Regression analysis revealed that intrinsic regulation was a negative predictor of competitive anxiety and somatic anxiety after controlling the effects of perfectionism and beliefs about success. [ABSTRACT FROM AUTHOR]

Geomorphic mass flows are often complex in terms of material composition and its evolution in space and time. The simulation of those hazardous phenomena would strongly benefit from a multi‐phase model, considering the motion and—importantly—interaction of phases characterized by different physical aspects including densities, frictions, viscosities, fractions, and their mechanical responses. However, such a genuine multi‐phase model is still lacking. Here, we present a first‐ever, multi‐mechanical, multi‐phase mass flow model composed of three different phases: the coarse solid fraction, fine‐solid fraction, and viscous fluid. The coarse solid component, called solid, represents boulders, cobbles, gravels, or blocks of ice. Fine‐solid represents fine particles and sand, whereas water and very fine particles, including colloids, silt, and clay, constitute the viscous fluid component in the mixture. The involved materials display distinct mechanical responses and dynamic behaviors. Therefore, the solid, fine‐solid, and fluid phases are described by Coulomb‐plastic, shear‐ and pressure‐dependent plasticity‐dominated viscoplastic, and viscosity‐dominated viscoplastic rheologies. They are supposed to best represent those materials. The new model is flexible and addresses some long‐standing issues of multi‐phase mass flows on how to reliably describe the flow dynamics, runout, and deposition morphology of such type of phenomena. With reference to some benchmark simulations, the essence of the model and its applicability are discussed. Key Points: We introduce a new multi‐mechanical, multi‐phase model accounting for the complexity of geomorphic mass flowsSolid, fine‐solid, and fluid fractions can be considered separately, allowing to simulate a broad range of possible material compositionsBenchmark tests on generic landscapes yield plausible results indicating the potential use of the new model for complex real events [ABSTRACT FROM AUTHOR]

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Moraine dam collapse is one of the causes of glacial lake outburst floods. Available models seek to predict both moraine breach formation and lake outflow. The models depend on hydraulic, erosion, and geotechnical parameters that are mostly unknown or uncertain. This paper estimates the outflow hydrograph caused by a potential erosive collapse of the moraine dam of Lake Palcacocha in Peru and quantifies the uncertainty of the results. The overall aim is to provide a simple yet hydraulically robust approach for calculating the expected outflow hydrographs that is useful for risk assessment studies. To estimate the peak outflow and failure time of the hydrograph, we assessed several available empirical equations based on lake and moraine geometries; each equation has defined confidence intervals for peak flow predictions. Complete outflow hydrographs for each peak flow condition were modeled using a hydraulic simulation model calibrated to match the peak flows estimated with the empirical equations. Failure time and peak flow differences between the simulations, and the corresponding empirical equations were used as error parameters. Along with an expected hydrograph, lower and upper bound hydrographs were calculated for Lake Palcacocha, representing the confidence interval of the results. The approach has several advantages: first, it is simple and robust. Second, it evaluates the capability of empirical equations to reproduce the conditions of the lake and moraine dam. Third, this approach accounts for uncertainty in the hydrographs estimations, which makes it appropriate for risk management studies. [ABSTRACT FROM AUTHOR]

For the flow and deposition behaviour of debris flows, phenomena like particle sorting, levee formation and the development of roll waves are expected to be important processes. However, these processes are not well understood and hardly implemented in modelling approaches. In this study, we focus on the development of roll waves and derive advanced criteria separating stable and instable flow regimes for three debris flow models. These criteria are expressed using critical Froude numbers. Each of these simple flow models reflect different sources of flow resistance: laminar-viscous stress (Bingham type), dispersive stress due to particle collision (Bagnold type), and a model combining turbulent and dispersive stresses. Subsequently, we compare the predictions from these models with results from laboratory experiments with grain–fluid mixtures in a straight flume and with observations from a debris flow monitoring site at the Lattenbach creek in Austria. The experimental flows match with a turbulent flow model including particle collisions. For the natural flows the connection between models and observations is not clear due to limited field data. The results of our study contribute to an improved determination of critical flow conditions and provide data for model testing. [ABSTRACT FROM AUTHOR]

Copyright of Acta Universitatis Carolinae Geographica is the property of Charles University Prague, Karolinum Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A debris-flow catastrophe hit the city of Zhouqu, Gansu Province, western China, at midnight on 7 August 2010 following a local extreme rainfall of 77.3mm h-1 in the Sanyanyu and Luojiayu ravines, which are located to the north of the urban area. Eight buildings damaged in the event were investigated in detail to study the characteristics and patterns of damage to buildings by debris flows. It was found that major structural damage was caused by the frontal impact of proximal debris flows, while non-structural damage was caused by lateral accumulation and abrasion of sediment. The impact had a boundary decreasing effect when debris flows encountered a series of obstacles, and the interpositioning of buildings produced so-called back shielding effects on the damage. Impact, accumulation, and abrasion were the three main patterns of damage to buildings in this event. The damage scale depended not only on the flow properties, such as density, velocity, and depth, but also on the structural strength of buildings, material, orientation, and geometry. Reinforced concrete-framed structures can effectively resist a much higher debris-flow impact than brickconcrete structures. With respect to the two typical types of structure, a classification scheme to assess building damage is proposed by referring to the Chinese Classification System of Earthquake Damage to Buildings. Furthermore, three damage scales (major structural, minor structural, and nonstructural damage) are defined by critical values of impact pressure. Finally, five countermeasures for effectively mitigating the damage are proposed according to the on-site investigation. [ABSTRACT FROM AUTHOR]