Artículos de revistas sobre el tema "Avalanche collapse"
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1
Lei, Yanbin, Tandong Yao, Lide Tian, Yongwei Sheng, Jingjuan Liao, Huabiao Zhao, Wei Yang et al. "Response of downstream lakes to Aru glacier collapses on the western Tibetan Plateau". Cryosphere 15, n.º 1 (14 de enero de 2021): 199–214. http://dx.doi.org/10.5194/tc-15-199-2021.
Resumen
Abstract. The lower parts of two glaciers in the Aru range on the western Tibetan Plateau (TP) collapsed on 17 July and 21 September 2016, respectively, causing fatal damage to local people and their livestock. The giant ice avalanches, with a total volume of 150 × 106 m3, had almost melted by September 2019 (about 30 % of the second ice avalanche remained). The impact of these extreme disasters on downstream lakes has not been investigated yet. Based on in situ observation, bathymetry survey and satellite data, we explore the impact of the ice avalanches on the two downstream lakes (i.e., Aru Co and Memar Co) in terms of lake morphology, water level and water temperature in the subsequent 4 years (2016–2019). After the first glacier collapse, the ice avalanche slid into Aru Co along with a large amount of debris, which generated great impact waves in Aru Co and significantly modified the lake's shoreline and underwater topography. An ice volume of at least 7.1 × 106 m3 was discharged into Aru Co, spread over the lake surface and considerably lowered its surface temperature by 2–4 ∘C in the first 2 weeks after the first glacier collapse. Due to the large amount of meltwater input, Memar Co exhibited more rapid expansion after the glacier collapses (2016–2019) than before (2003–2014), in particular during the warm season. The melting of ice avalanches was found to contribute to about 23 % of the increase in lake storage between 2016 and 2019. Our results indicate that the Aru glacier collapses had both short-term and long-term impacts on the downstream lakes and provide a baseline in understanding the future lake response to glacier melting on the TP under a warming climate.
2
Baroudi, D., B. Sovilla y E. Thibert. "Effects of flow regime and sensor geometry on snow avalanche impact-pressure measurements". Journal of Glaciology 57, n.º 202 (2011): 277–88. http://dx.doi.org/10.3189/002214311796405988.
Resumen
AbstractImpact pressures of snow avalanches have been measured at the Swiss Vallée de la Sionne experimental test site using two kinds of sensor placed at different locations in the avalanche flow. Pressures measured in a fast dry-snow avalanche and a slow wet-snow avalanche are compared and discussed. The pressures recorded using the two types of sensor in the dense flow of a dry-snow avalanche agree well, showing negligible dependence on the measurement device. On the other hand, significantly different pressures are measured in the slow dense flow of a wet-snow avalanche. This is attributed to the slow drag and bulk flow of this type of avalanche, leading to the formation and collapse of force-chain structures against the different surfaces of the sensors. At a macroscopic scale, limit state analysis can be used to explain such a mechanism by a shear failure occurring between freely flowing snow and a confined snow volume against the sensor, according to a Mohr–Coulomb failure criterion. The proposed model explains (1) how impact pressure can be up to eight times higher than hydrostatic snow pressure in wet cohesive slow avalanches and (2) its dependence on sensor geometry.
3
Azhgaliyeva, B. A. "Some issues on prevention of avalanche coloring of building structures". Bulletin of Kazakh Leading Academy of Architecture and Construction 80, n.º 2 (29 de junio de 2021): 150–56. http://dx.doi.org/10.51488/1680-080x/2021.2-41.
Resumen
The article discusses the emergence of the problem of an avalanche collapse of a building and various ways to prevent collapse of structures. On the basis of world experience, recommendations are made for protection against avalanche collapse of high-rise buildings of various structural systems.
4
Stewart, M. L., J. K. Russell y C. J. Hickson. "Discrimination of hot versus cold avalanche deposits: Implications for hazard assessment at Mount Meager, B.C." Natural Hazards and Earth System Sciences 3, n.º 6 (31 de diciembre de 2003): 713–24. http://dx.doi.org/10.5194/nhess-3-713-2003.
Resumen
Abstract. The surficial deposits surrounding the Mount Meager volcanic complex include numerous avalanche deposits. These deposits share many attributes: (a) they are nearly monolithologic and comprise mainly intermediate volcanic rock clasts, (b) they lack internal structure, and (c) they are very poorly sorted. Despite these similarities, the avalanche deposits represent two distinct processes. Mass wasting of the Mount Meager volcanic edifice has produced cold rock avalanche deposits, whereas gravitational collapse of active lava domes and flows has produced hot block and ash avalanche deposits. The ability to discriminate between these "hot" and "cold" avalanche deposits is a critical component in the assessment of hazards in volcanic terranes. Hot block and ash avalanche deposits can be distinguished by the presence of radially-oriented joints, breadcrust textures, and incipient welding, which are features indicative of high emplacement temperatures. Conversely, rock avalanche deposits resulting from mass wasting events may be distinguished by the presence of clasts that preserve pre-depositional weathering and jointing surfaces. Volcanic avalanches are mechanically similar to rock avalanches but pose a greater hazard due to high temperatures, increased fluidization from degassing and the potential to decouple highly mobile elutriated ash clouds. The increasing use of hazardous regions such as the Lillooet River valley requires more reliable risk assessment in order to minimize losses from future hazardous events.
5
Agatova, Anna, Roman Nepop, Dmitry Ganyushkin, Demberel Otgonbayar, Semen Griga y 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, n.º 4 (14 de febrero de 2022): 917. http://dx.doi.org/10.3390/rs14040917.
Resumen
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
Plaza, F., M. G. Velarde, F. T. Arecchi, S. Boccaletti, M. Ciofini y R. Meucci. "Excitability following an avalanche-collapse process". Europhysics Letters (EPL) 38, n.º 2 (10 de abril de 1997): 85–90. http://dx.doi.org/10.1209/epl/i1997-00205-7.
7
Wadge, G., P. W. Francis y C. F. Ramirez. "The Socompa collapse and avalanche event". Journal of Volcanology and Geothermal Research 66, n.º 1-4 (julio de 1995): 309–36. http://dx.doi.org/10.1016/0377-0273(94)00083-s.
8
Jeitschko, Thomas D. y Curtis R. Taylor. "Local Discouragement and Global Collapse: A Theory of Coordination Avalanches". American Economic Review 91, n.º 1 (1 de marzo de 2001): 208–24. http://dx.doi.org/10.1257/aer.91.1.208.
Resumen
We study a dynamic game in which all players initially possess the same information and coordinate on a high level of activity. Eventually, players with a long string of bad experiences become inactive. This prospect can cause a coordination avalanche in which all activity in the population stops. Coordination avalanches are part of Pareto-efficient equilibria; they can occur at any point in the game; their occurrence does not depend on the true state of nature; and allowing players to exchange information may merely hasten their onset. We present applications to search markets, organizational meltdown, and inefficient computer upgrades. (JEL D83)
9
Bovet, Eloise, Bernardino Chiaia, Valerio De Biagi y Barbara Frigo. "Pressure of Snow Avalanches against Buildings". Applied Mechanics and Materials 82 (julio de 2011): 392–97. http://dx.doi.org/10.4028/www.scientific.net/amm.82.392.
Resumen
The paper aims to analyse the e ects of topography and building position on themagnitude of pressure exerted by snow avalanches against buildings, through a structural backanalysis and numerical uid-dynamics. Studying a real snow avalanche impact occurred in2008 which destroyed a village in Valsavarenche (Aosta Valley - IT), the attention is focused onthe avalanche ow deviation caused by the destructive interaction with a rst building, whichprotected part of a second building beyond it. By means of photographical and in situ survey,a detailed description of avalanche geometrical, dynamical and physical properties is outlined.A structural investigation, based both on debris arrangement and on measurements on theundamaged parts of buildings is also carried out.Thus, a back analysis is carried out in order to de ne collapse dynamics and to estimate theupper and the lower bound of impact pressure. Afterwards, numerical uid-dynamical analysesare performed to simulate di erent impact scenarios and to understand the e ects of obstacleson avalanche behavior: a qualitative measure of the interactions among buildings, which maymutually protect one another, is obtained.
10
Van Wyk de Vries, Maximillian, Shashank Bhushan, Mylène Jacquemart, César Deschamps-Berger, Etienne Berthier, Simon Gascoin, David E. Shean, Dan H. Shugar y Andreas Kääb. "Pre-collapse motion of the February 2021 Chamoli rock–ice avalanche, Indian Himalaya". Natural Hazards and Earth System Sciences 22, n.º 10 (13 de octubre de 2022): 3309–27. http://dx.doi.org/10.5194/nhess-22-3309-2022.
Resumen
Abstract. Landslides are a major geohazard that cause thousands of fatalities every year. Despite their importance, identifying unstable slopes and forecasting collapses remains a major challenge. In this study, we use the 7 February 2021 Chamoli rock–ice avalanche as a data-rich example to investigate the potential of remotely sensed datasets for the assessment of slope stability. We investigate imagery over the 3 decades preceding collapse and assess the precursory signs exhibited by this slope prior to the catastrophic collapse. We evaluate monthly slope motion from 2015 to 2021 through feature tracking of high-resolution optical satellite imagery. We then combine these data with a time series of pre- and post-event digital elevation models (DEMs), which we use to evaluate elevation change over the same area. Both datasets show that the 26.9×106 m3 collapse block moved over 10 m horizontally and vertically in the 5 years preceding collapse, with particularly rapid motion occurring in the summers of 2017 and 2018. We propose that the collapse results from a combination of snow loading in a deep headwall crack and permafrost degradation in the heavily jointed bedrock. Despite observing a clear precursory signal, we find that the timing of the Chamoli rock–ice avalanche could likely not have been forecast from satellite data alone. Our results highlight the potential of remotely sensed imagery for assessing landslide hazard in remote areas, but that challenges remain for operational hazard monitoring.
11
Falaschi, Daniel, Andreas Kääb, Frank Paul, Takeo Tadono, Juan Antonio Rivera y Luis Eduardo Lenzano. "Brief communication: Collapse of 4 Mm<sup>3</sup> of ice from a cirque glacier in the Central Andes of Argentina". Cryosphere 13, n.º 3 (26 de marzo de 2019): 997–1004. http://dx.doi.org/10.5194/tc-13-997-2019.
Resumen
Abstract. Among glacier instabilities, collapses of large parts of low-angle glaciers are a striking, exceptional phenomenon. So far, merely the 2002 collapse of Kolka Glacier in the Caucasus Mountains and the 2016 twin detachments of the Aru glaciers in western Tibet have been well documented. Here we report on the previously unnoticed collapse of an unnamed cirque glacier in the Central Andes of Argentina in March 2007. Although of much smaller ice volume, this 4.2±0.6×106 m3 collapse in the Andes is similar to the Caucasus and Tibet ones in that the resulting ice avalanche travelled a total distance of ∼2 km over a surprisingly low angle of reach (∼5∘).
12
PLAZA, F. y M. G. VELARDE. "AVALANCHE-COLLAPSE MECHANISM: A MODEL FOR EXCITABILITY". International Journal of Bifurcation and Chaos 06, n.º 10 (octubre de 1996): 1873–81. http://dx.doi.org/10.1142/s021812749600120x.
Resumen
We propose a new type of excitability mechanism, based on an avalanche-collapse process. We show the differences and similarities between this and the already known excitability concepts for biological and mechanical systems. An experiment is also proposed with a laser containing a saturable absorber inside the cavity.
13
Deline, P., W. Alberto, M. Broccolato, O. Hungr, J. Noetzli, L. Ravanel y A. Tamburini. "The December 2008 Crammont rock avalanche, Mont Blanc massif area, Italy". Natural Hazards and Earth System Sciences 11, n.º 12 (15 de diciembre de 2011): 3307–18. http://dx.doi.org/10.5194/nhess-11-3307-2011.
Resumen
Abstract. We describe a 0.5 Mm3 rock avalanche that occurred in 2008 in the western Alps and discuss possible roles of controlling factors in the context of current climate change. The source is located between 2410 m and 2653 m a.s.l. on Mont Crammont and is controlled by a densely fractured rock structure. The main part of the collapsed rock mass deposited at the foot of the rock wall. A smaller part travelled much farther, reaching horizontal and vertical travel distances of 3050 m and 1560 m, respectively. The mobility of the rock mass was enhanced by channelization and snow. The rock-avalanche volume was calculated by comparison of pre- and post-event DTMs, and geomechanical characterization of the detachment zone was extracted from LiDAR point cloud processing. Back analysis of the rock-avalanche runout suggests a two stage event. There was no previous rock avalanche activity from the Mont Crammont ridge during the Holocene. The 2008 rock avalanche may have resulted from permafrost degradation in the steep rock wall, as suggested by seepage water in the scar after the collapse in spite of negative air temperatures, and modelling of rock temperatures that indicate warm permafrost (T > −2 °C).
14
Nagai, Hiroto, Manabu Watanabe, Naoya Tomii, Takeo Tadono y 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, n.º 11 (13 de noviembre de 2017): 1907–21. http://dx.doi.org/10.5194/nhess-17-1907-2017.
Resumen
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.
15
Serrano, M. Ángeles, Ľuboš Buzna y Marián Boguñá. "Escaping the avalanche collapse in self-similar multiplexes". New Journal of Physics 17, n.º 5 (22 de mayo de 2015): 053033. http://dx.doi.org/10.1088/1367-2630/17/5/053033.
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Favier, P., D. Bertrand, N. Eckert y M. Naaim. "A reliability assessment of physical vulnerability of reinforced concrete walls loaded by snow avalanches". Natural Hazards and Earth System Sciences Discussions 1, n.º 3 (7 de junio de 2013): 2589–632. http://dx.doi.org/10.5194/nhessd-1-2589-2013.
Resumen
Abstract. Snow avalanches are a threat to many kinds of elements (human beings, communication axes, structures, etc.) in mountain regions. For risk evaluation, the vulnerability assessment of civil engineering structures such as buildings and dwellings exposed to avalanches still needs to be improved. This paper presents an approach to determine the fragility curves associated with Reinforced Concrete (RC) structures loaded by typical avalanche pressures and provides quantitative results for different geometrical configurations. First, several mechanical limit states of the RC wall are defined using classical engineering approaches (Eurocodes – EC2), and the pressure of structure collapse is calculated from the usual yield line theory. Next, the failure probability is evaluated as a function of avalanche loading using a Monte Carlo approach, and sensitivity studies (Sobol indexes) are conducted to estimate the respective weight of the RC wall model inputs. Finally, fragility curves and relevant indicators such a their mean and fragility range are proposed for the different structure boundary conditions tested. The influence of the input distributions on the fragility curves is investigated. This shows the wider fragility range and/or the slight shift in the median that has to be considered when the possible correlation/non-Gaussian nature of the input distributions is accounted for.
17
Van Compernolle, B., M. J. Poulos y G. J. Morales. "Sudden collapse of a pressure profile generated by off-axis heating in a linear magnetized plasma". Physics of Plasmas 29, n.º 4 (abril de 2022): 042104. http://dx.doi.org/10.1063/5.0082247.
Resumen
The features of an unexpected, large event that arises spontaneously during a basic heat transport experiment are presented. It consists of the sudden collapse of the radial plasma pressure profile, akin to disruption events observed in toroidal magnetic confinement devices. The experiment is performed on the Large Plasma Device at the University of California, Los Angeles (UCLA). It uses a LaB6 thermionic emitter of annular shape to induce off-axis heating of a cold, afterglow plasma, in a linear magnetic geometry. The temporal evolution consists of three regimes. During an early, quiescent period, classical heat transport along and across the magnetic field arises from Coulomb collisions. After significant pressure gradients develop, drift-Alfvén waves become unstable. Upon reaching large amplitude, they trigger avalanche events that flatten the outer part of the heated region, which, in turn, quenches the instability. Due to the sustained heating, the pressure profile rebuilds and the process repeats, leading to a relatively long, second regime that displays multiple avalanches, but suddenly, the annular pressure profile is observed to collapse. After this collapse, the system enters a third regime with large fluctuations. Before the collapse, a rapid, runaway heating environment arises whose time evolution exhibits a self-similar dependence on the applied voltage. The time evolution, morphology, and scaling of the collapse event are presented, and an examination is made of the underlying mechanisms.
18
Gilbert, Adrien, Silvan Leinss, Jeffrey Kargel, Andreas Kääb, Simon Gascoin, Gregory Leonard, Etienne Berthier, Alina Karki y Tandong Yao. "Mechanisms leading to the 2016 giant twin glacier collapses, Aru Range, Tibet". Cryosphere 12, n.º 9 (7 de septiembre de 2018): 2883–900. http://dx.doi.org/10.5194/tc-12-2883-2018.
Resumen
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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Reznik, Petro, Mohamd Almohamad y Vladyslav Tenesesku. "ANALYSIS OF CONSTRUCTIVE SOLUTIONS OF THE EXISTING BUILDINGS OF THE HOUSING FUND OF THE KHARKIV CITY ON THE SUBJECT OF THEIR PERFORMANCE AS A CONSEQUENCE OF THE INFLUENCE OF COMBAT ACTIONS". Collection of Scientific Works of the Ukrainian State University of Railway Transport, n.º 201 (30 de septiembre de 2022): 41–56. http://dx.doi.org/10.18664/1994-7852.201.2022.267755.
Resumen
The article examines the main structural solutions of existing residential buildings inthe city of Kharkiv and analyzes their working capacity from the point of view of resistance toexplosive effects and, as a result, progressive collapse. It is known that progressive collapse ischaracteristic of extreme (emergency) cases, when due to destruction of a responsible element of thestructure as a result of a gas explosion, ammunition bursts, climatic cataclysms, transport collapses,etc a part of the building or the entire structure collapses. It is noted that every year, the interest ofthe world scientific community in the issues of progressive collapse is growing, because,unfortunately, the number of cases of avalanche-like collapse of buildings of various types isincreasing. This was facilitated by already known cases of collapses of various objects, such as theRonan Point residential building (Great Britain) in 1968 or the buildings of the World Trade Center(USA) in 2011, or the very recent case of the collapse of a residential building in Surfside (USA) in2021. At the same time, it is noted that domestic regulations do not yet specify the methodology forcalculating buildings before progressive collapse, and the existing methods of experimental andnumerical analysis still need to be refined. Unfortunately, the list of such objects is increasing, andtoday, Ukraine has added to it numerous destroyed buildings as a result of ongoing hostilities on itsterritory. Therefore, for our country in the current conditions, the issue of ensuring the future stability of all buildings, and in particular, the housing stock against progressive collapse, is an urgent issue.On the basis of the analysis of the constructive solutions of the housing development in the city ofKharkiv, the type of buildings that, according to the authors of the article, has the greatest resource,is singled out, and brief recommendations are given for its increase in the future.
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Hayakawa, Yuichi S., Hidetsugu Yoshida, Hiroyuki Obanawa, Ryutaro Naruhashi, Koji Okumura, Masumi Zaiki y Ryoichi Kontani. "Characteristics of debris avalanche deposits inferred from source volume estimate and hummock morphology around Mt. Erciyes, central Turkey". Natural Hazards and Earth System Sciences 18, n.º 2 (7 de febrero de 2018): 429–44. http://dx.doi.org/10.5194/nhess-18-429-2018.
Resumen
Abstract. Debris avalanches caused by volcano sector collapse often form characteristic depositional landforms such as hummocks. Sedimentological and geomorphological analyses of debris avalanche deposits (DADs) are crucial to clarify the size, mechanisms, and emplacement of debris avalanches. We describe the morphology of hummocks on the northeastern flank of Mt. Erciyes in Kayseri, central Turkey, likely formed in the late Pleistocene. Using a remotely piloted aircraft system (RPAS) and the structure-from-motion and multi-view stereo (SfM–MVS) photogrammetry, we obtained high-definition digital elevation model (DEM) and orthorectified images of the hummocks to investigate their geometric features. We estimated the source volume of the DAD by reconstructing the topography of the volcano edifice using a satellite-based DEM. We examined the topographic cross sections based on the slopes around the scar regarded as remnant topography. Spatial distribution of hummocks is anomalously concentrated at a certain distance from the source, unlike those that follow the distance–size relationship. The high-definition land surface data by RPAS and SfM revealed that many of the hummocks are aligned toward the flow direction of the debris avalanche, suggesting that the extensional regime of the debris avalanche was dominant. However, some displaced hummocks were also found, indicating that the compressional regime of the flow contributed to the formation of hummocks. These indicate that the flow and emplacement of the avalanche were constrained by the topography. The existing caldera wall forced the initial eastward flow to move northward, and the north-side caldera wall forced the flow into the narrow and steepened outlet valley where the sliding debris underwent a compressional regime, and out into the unconfined terrain where the debris was most likely emplaced on an extensional regime. Also, the estimated volume of 12–15 × 108 m3 gives a mean thickness of 60–75 m, which is much deeper than the reported cases of other DADs. This suggests that the debris avalanche must have flowed further downstream and beyond the current DAD extent. Assessments of the DAD incorporating the topographic constraints can provide further insights into the risk and mitigation of potential disasters in the study area.
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Moktikanana, M. L. A., H. E. Wibowo, E. Rahayu y A. Harijoko. "Hummock size and alignment in Gadung debris avalanche deposit, Raung Volcanic Complex, East Java, Indonesia". IOP Conference Series: Earth and Environmental Science 851, n.º 1 (1 de octubre de 2021): 012037. http://dx.doi.org/10.1088/1755-1315/851/1/012037.
Resumen
Abstract Debris avalanche deposit is formed by the failure of volcanic edifice and has a high potential to directly impact human civilization. The famous characteristic landform of debris avalanche deposit is hummocky hills. To understand the dynamics of avalanche flow, we investigate the morphometric characters of debris avalanche hummocks from Gunung Gadung in Raung Volcanic Complex. The collapse of Gunung Gadung follows two main flow direction with two different kinds of debris avalanche, i.e., freely spreading and valley filling. Our study recorded that there is no significant correlation between hummock size and distance from the source. The distribution of Gadung hummock size is mainly controlled by pre-existing morphologic feature such as Iyang-Argapura Volcanic Complex and Meru Betiri Mountains. We identify four domains area of Gadung debris avalanche flow based on hummock size distribution, which are Toreva domain, Hummock domain, Collision domain, and Oblique collision domain. Hummock orientation and displacement angle of Gadung debris avalanche deposit depend on structural regime existed in certain area. Compressional regime may occur because of collision between Gadung avalanche flow and Iyang-Argapura Volcanic Complex, or shifting of main flow direction. Meanwhile, extensional regime may happen due to decreasing in slope and spreading of avalanche flow.
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Montanaro, C. y J. Beget. "Volcano collapse along the Aleutian Ridge (western Aleutian Arc)". Natural Hazards and Earth System Sciences 11, n.º 3 (8 de marzo de 2011): 715–30. http://dx.doi.org/10.5194/nhess-11-715-2011.
Resumen
Abstract. The Aleutian Ridge, in the western part of the Aleutian Arc, consists of a chain of volcanic islands perched atop the crest of a submarine ridge with most of the active Quaternary stratocones or caldera-like volcanoes being located on the northern margins of the Aleutian Islands. Integrated analysis of marine and terrestrial data resulted in the identification and characterization of 17 extensive submarine debris avalanche deposits from 11 volcanoes. Two morphological types of deposits are recognizable, elongate and lobate, with primary controls on the size and distribution of the volcanic debris being the volume and nature of material involved, proportion of fine grained material, depth of emplacement and the paleo-bathymetry. Volume calculations show the amount of material deposited in debris avalanches is as much as three times larger than the amount of material initially involved in the collapse, suggesting the incorporation of large amounts of submarine material during transport. The orientation of the collapse events is influenced by regional fault systems underling the volcanoes. The western Aleutian Arc has a significant tsunamigenic potential and communities within the Aleutian Islands and surrounding areas of the North Pacific as well as shipping and fishing fleets that cross the North Pacific may be at risk during future eruptions in this area.
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Favier, P., D. Bertrand, N. Eckert y M. Naaim. "A reliability assessment of physical vulnerability of reinforced concrete walls loaded by snow avalanches". Natural Hazards and Earth System Sciences 14, n.º 3 (27 de marzo de 2014): 689–704. http://dx.doi.org/10.5194/nhess-14-689-2014.
Resumen
Abstract. Snow avalanches are a threat to many kinds of elements (human beings, communication axes, structures, etc.) in mountain regions. For risk evaluation, the vulnerability assessment of civil engineering structures such as buildings and dwellings exposed to avalanches still needs to be improved. This paper presents an approach to determine the fragility curves associated with reinforced concrete (RC) structures loaded by typical avalanche pressures and provides quantitative results for different geometrical configurations. First, several mechanical limit states of the RC wall are defined using classical engineering approaches (Eurocode 2), and the pressure of structure collapse is calculated from the usual yield line theory. Next, the fragility curve is evaluated as a function of avalanche loading using a Monte Carlo approach, and sensitivity studies (Sobol indices) are conducted to estimate the respective weight of the RC wall model inputs. Finally, fragility curves and relevant indicators such a their mean and fragility range are proposed for the different structure boundary conditions analyzed. The influence of the input distributions on the fragility curves is investigated. This shows the wider fragility range and/or the slight shift in the median that has to be considered when a possible slight change in mean/standard deviation/inter-variable correlation and/or the non-Gaussian nature of the input distributions is accounted for.
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Bartelt, Perry, Othmar Buser, Cesar Vera Valero y Yves Bühler. "Configurational energy and the formation of mixed flowing/powder snow and ice avalanches". Annals of Glaciology 57, n.º 71 (enero de 2016): 179–88. http://dx.doi.org/10.3189/2016aog71a464.
Resumen
Abstract.A long-standing problem in avalanche dynamics is to model the flow of a mixed flowing/powder avalanche. Here we use the thermodynamic concept of configurational energy to describe the blow-out of air from the avalanche core. Configurational energy is the mean potential energy associated with the location of snow and ice particles in the avalanche core. As such, configurational energy determines the avalanche flow density. Expansion of the particle ensemble reduces the flow density and leads to the intake of air. Compression of the particle ensemble causes the blow-out of the intaken air, now laden with ice dust. Once formed, the cloud moves independently of the flowing avalanche with the initial momentum acquired in the core. Configurational energy changes in the avalanche core are therefore intimately related to the formation of the powder suspension cloud. In this paper we use the concept of configurational energy to predict the mass of air taken into and blown out of the core. This requires calculating the dispersive pressure arising from random particle movements and configuration changes related to the expansion and collapse of the flowing particle ensemble. The ice avalanche that struck the Everest base camp on 25 April 2015 is simulated using the proposed concept.
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Nehlig, Pierre, Herve Leyrit, Arnaud Dardon, Gwenael Freour, Alain de Goer de Herve, David Huguet y Denis Thieblemont. "Constructions et destructions du stratovolcan du Cantal". Bulletin de la Société Géologique de France 172, n.º 3 (1 de mayo de 2001): 295–308. http://dx.doi.org/10.2113/172.3.295.
Resumen
Abstract The Cantal (France) stratovolcano, which is 70 km in diameter and extends 2500 km 2 , is the largest perialpine stratovolcano. Due to its size and the abundance of breccia, it has never before been the subject of a comprehensive synthesis, despite being considered in more than 30 doctoral theses and over 200 scientific papers, memoirs and reports. An intensive research project, which integrates a synthesis of existing published and unpublished data and new geological, geochemical, geophysical and geochronological data, along with 1:25,000-scale mapping of the central part of the stratovolcano, has led to the production of the first 1:50,000-scale map of the central part of the volcano and a 1:100,000-scale map of the entire volcano. The present mapping and analytical work has led to an entirely new conceptual view of the geological history of the stratovolcano and to a reinterpretation of the previously defined stratigraphic units and their volcanological significance. This paper presents a brief geological history, focussing on the abundant primary and secondary breccia (lahar and debris-avalanche deposits) that make up most of the volcano, and reviews a number of dogmas and uncertainties concerning the volcano and its evolution. The stratovolcano was emplaced between 13 and 2 Ma on an uplifted Hercynian basement associated with Oligocene sedimentary basins. The overall geometry of the Cantal stratovolcano is rather simple, composed of a central trachyandesitic volcano surrounded by debris-avalanche and debris-flow deposits sandwiched between two basaltic lava flows. Basaltic lava erupted first, between 13 and 7 Ma, with a peak activity around 9 Ma. Trachyandesitic lava with minor trachyte and rhyolite was erupted towards the end of the basaltic activity, between 10 and 6.5 Ma, although mainly between 8.5 and 7 Ma. This episode led to the construction of a high stratovolcano and its associated laharic apron. The edifice collapsed several times and produced gigantic debris-avalanche deposits that are widespread in the Cantal and as far as 40 km from its centre. The last stages of trachyandesitic activity were synchronous with the emplacement of phonolitic domes between 7.5 and 5.5 Ma. This intrusive event was followed by extensive basaltic lava flows that covered most of the Cantal. The present geometry of the Cantal volcano is the result of these phases of construction and cataclysmic destruction followed by intense glacial and periglacial erosion. The ages of emplacement of the debris-avalanche deposits are now well constrained by abundant isotopic data obtained from the overlying, underlying and included blocks. They imply that several large debris-avalanches affected the flanks of the Cantal volcano between 8.0 and 6.8 Ma. The deposits are in chronological order and separated by episodes of volcanic construction: -- the deposits in the north and east (Rhues, Veronne, Impradine, Santoire, Alagnon Chevade valleys), dated at before 7,4 Ma, form a highly discontinuous, thin eroded layer that is overlain by a thick volcanoclastic laharic piedmont derived from the subsequent phases of volcanic construction; -- the deposits in the west (Marilhou, Mars, Maronne, Aspre, Bertrande valleys) are dated at between 7.2 et 7.4 Ma; -- the deposits in the southwest (Doire, Authre, Jordanne, Cere and Epie valleys) are dated at between 7.4 and 6.8 Ma; -- the deposits in the south (Goul and Brezons valleys) younger than 7.1 Ma and emplaced before the Cere deposit. The absence of a laharic unit on top of the southwestern debris-avalanche deposits is in agreement with this succession of volcanic construction and destruction, as it implies the absence of any major volcanic construction after the last gravitational collapse. All the other sectors are characterized by thick debris-flow deposits overlying the debris-avalanche deposits. This chronological succession of events invalidates the previously proposed debris-avalanche chronologies. The present-day total volume of debris-avalanche deposits is around 245 km 3 for a total volcanic volume of 385 km 3 . Individual debris-avalanche bodies have volumes of several tens of km 3 . Well-characterized prehistoric and historic debris-avalanche bodies have height/length ratios around 0.1. Taking this good correlation into account suggests altitudes above 3000 m for the Cantal paleovolcano and explains the high paleoslopes observed in its central part. Previous models required the existence of a gigantic caldera ("fosse volcano-tectonique") in the central part of the volcano to account for the abundant "pyroclastic rocks" now interpreted as debris-avalanche deposits. This caldera and smaller ones were geophysically and geochronologically documented. New geophysical and geological expertise, however, has revealed the absence of such features. The detailed mapping has shown that the Cantal stratovolcano is mainly the result of several phases of construction and destruction over a relatively short period from 8.5 to 6.5 Ma. The construction phases led to the edification, over several hundred thousand years, of trachyandesitic volcanoes (25 km in diameter and more than 3000 m high) surrounded by debris deposits (laharic piedmont, 40 km in diameter). Due to the high viscosity of the trachyandesitic material, each construction phase resulted in major gravitational collapse, causing a large debris avalanche talus (70 km in diameter) around the central volcano. The last collapse in the southwest was not followed by a construction event, as indicated by the absence of overlying debris-flow deposits and by the flat morphology sealed by the upper basaltic flows.
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Barrett, Rachel, Elodie Lebas, Ricardo Ramalho, Ingo Klaucke, Steffen Kutterolf, Andreas Klügel, Katja Lindhorst, Felix Gross y Sebastian Krastel. "Revisiting the tsunamigenic volcanic flank collapse of Fogo Island in the Cape Verdes, offshore West Africa". Geological Society, London, Special Publications 500, n.º 1 (19 de diciembre de 2019): 13–26. http://dx.doi.org/10.1144/sp500-2019-187.
Resumen
AbstractVolcanic archipelagos are a source of numerous on- and offshore geohazards, including explosive eruptions and potentially tsunamigenic large-scale flank collapses. Fogo Island in the southern Cape Verdes is one of the most active volcanoes in the world, making it both prone to collapse (as evidenced by the c. 73 ka Monte Amarelo volcanic flank collapse), and a source of widely distributed tephra and volcanic material. The offshore distribution of the Monte Amarelo debris avalanche deposits and the surrounding volcaniclastic apron were previously mapped using only medium-resolution bathymetric data. Here, using recently acquired, higher-resolution acoustic data, we revisit Fogo's flank collapse and find evidence suggesting that the deposition of hummocky volcanic debris originating from the failed eastern flank most likely triggered the contemporaneous, multi-phase failure of pre-existing seafloor sediments. Additionally, we identify, for the first time, multiple mass-transport deposits in the southern part of the volcaniclastic apron of Fogo and Santiago based on the presence of acoustically chaotic deposits in parametric echo sounder data and volcaniclastic turbiditic sands in recovered cores. These preliminary findings indicate a long and complex history of instability on the southern slopes of Fogo and suggest that Fogo may have experienced multiple flank collapses.
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Gisbert, Guillem, Hugo Delgado-Granados, Martin Mangler, Julie Prytulak, Ramón Espinasa-Pereña y Chiara Maria Petrone. "Evolution of the Popocatépetl Volcanic Complex: constraints on periodic edifice construction and destruction by sector collapse". Journal of the Geological Society 179, n.º 3 (19 de noviembre de 2021): jgs2021–022. http://dx.doi.org/10.1144/jgs2021-022.
Resumen
Popocatépetl is one of the most active volcanoes in North America. Its current predominantly mild activity is contrasted by a history of large effusive and explosive eruptions and sector collapse events, first summarized by Espinasa-Pereña and Martín-Del Pozzo (2006). Since then, a wealth of new radiometric, geophysical and volcanological data have been published, requiring a re-evaluation of the evolution of the Popocatépetl Volcanic Complex (PVC). We combined existing literature data with new field observations, aerial imagery and digital elevation model interpretations to produce an updated and improved reconstruction of the growth and evolution of the PVC throughout its history. This will be fundamental for the assessment and mitigation of risks associated with potential future high-magnitude activity of the PVC. The PVC consists of four successive volcanic edifices separated by three sector collapse events producing avalanche deposits: Tlamacas (>538–>330 ka, described here for the first time); Nexpayantla (c. 330 to >98 ka); Ventorrillo (c. 98–23.5 ka); and Popocatépetl (<23.5 ka). The newly described Tlamacas collapse propagated towards the ENE, forming part of the Mayorazgo avalanche deposit.Supplementary material: Supplementary files 1–7 are available at https://doi.org/10.6084/m9.figshare.c.5709190
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Waythomas, Christopher F. y Kristi L. Wallace. "Flank collapse at Mount Wrangell, Alaska, recorded by volcanic mass-flow deposits in the Copper River lowland". Canadian Journal of Earth Sciences 39, n.º 8 (1 de agosto de 2002): 1257–79. http://dx.doi.org/10.1139/e02-032.
Resumen
An areally extensive volcanic mass-flow deposit of Pleistocene age, known as the Chetaslina volcanic mass-flow deposit, is a prominent and visually striking deposit in the southeastern Copper River lowland of south-central Alaska. The mass-flow deposit consists of a diverse mixture of colorful, variably altered volcanic rocks, lahar deposits, glaciolacustrine diamicton, and till that record a major flank collapse on the southwest flank of Mount Wrangell. The deposit is well exposed near its presumed source, and thick, continuous, stratigraphic exposures have permitted us to study its sedimentary characteristics as a means of better understanding the origin, significance, and evolution of the deposit. Deposits of the Chetaslina volcanic mass flow in the Chetaslina River drainage are primary debris-avalanche deposits and consist of two principal facies types, a near-source block facies and a distal mixed facies. The block facies is composed entirely of block-supported, shattered and fractured blocks with individual blocks up to 40 m in diameter. The mixed facies consists of block-sized particles in a matrix of poorly sorted rock rubble, sand, and silt generated by the comminution of larger blocks. Deposits of the Chetaslina volcanic mass flow exposed along the Copper, Tonsina, and Chitina rivers are debris-flow deposits that evolved from the debris-avalanche component of the flow and from erosion and entrainment of local glacial and glaciolacustrine diamicton in the Copper River lowland. The debris-flow deposits were probably generated through mixing of the distal debris avalanche with the ancestral Copper River, or through breaching of a debris-avalanche dam across the ancestral river. The distribution of facies types and major-element chemistry of clasts in the deposit indicate that its source was an ancestral volcanic edifice, informally known as the Chetaslina vent, on the southwest side of Mount Wrangell. A major sector collapse of the Chetaslina vent initiated the Chetaslina volcanic mass flow forming a debris avalanche of about 4 km3 that subsequently transformed to a debris flow of unknown volume.
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Jiang, Wen-Jun, Run-Ran Liu y Chun-Xiao Jia. "Depth Penetration and Scope Extension of Failures in the Cascading of Multilayer Networks". Complexity 2020 (25 de abril de 2020): 1–11. http://dx.doi.org/10.1155/2020/3578736.
Resumen
Real-world complex systems always interact with each other, which causes these systems to collapse in an avalanche or cascading manner in the case of random failures or malicious attacks. The robustness of multilayer networks has attracted great interest, where the modeling and theoretical studies of which always rely on the concept of multilayer networks and percolation methods. A straightforward and tacit assumption is that the interdependence across network layers is strong, which means that a node will fail entirely with the removal of all links if one of its interdependent nodes in other network layers fails. However, this oversimplification cannot describe the general form of interactions across the network layers in a real-world multilayer system. In this paper, we reveal the nature of the avalanche disintegration of general multilayer networks with arbitrary interdependency strength across network layers. Specifically, we identify that the avalanche process of the whole system can essentially be decomposed into two microscopic cascading dynamics in terms of the propagation direction of the failures: depth penetration and scope extension. In the process of depth penetration, the failures propagate from layer to layer, where the greater the number of failed nodes is, the greater is the destructive power that will emerge in an interdependency group. In the process of scope extension, failures propagate with the removal of connections in each network layer. Under the synergy of the two processes, we find that the percolation transition of the system can be discontinuous or continuous with changes in the interdependency strength across network layers, which means that a sudden system-wide collapse can be avoided by controlling the interdependency strength across network layers. Our work not only reveals the microscopic mechanism of global collapse in multilayer infrastructure systems but also provides stimulating ideas on intervention programs and approaches for cascade failures.
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Li, Shudong, Yanshan Chen, Xiaobo Wu, Xiaochun Cheng y Zhihong Tian. "Power Grid-Oriented Cascading Failure Vulnerability Identifying Method Based on Wireless Sensors". Journal of Sensors 2021 (26 de junio de 2021): 1–12. http://dx.doi.org/10.1155/2021/8820413.
Resumen
In our paper, we study the vulnerability in cascading failures of the real-world network (power grid) under intentional attacks. Here, we use three indexes ( B , K , k -shell) to measure the importance of nodes; that is, we define three attacks, respectively. Under these attacks, we measure the process of cascade effect in network by the number of avalanche nodes, the time steps, and the speed of the cascade propagation. Also, we define the node’s bearing capacity as a tolerant parameter to study the robustness of the network under three attacks. Taking the power grid as an example, we have obtained a good regularity of the collapse of the network when the node’s affordability is low. In terms of time and speed, under the betweenness-based attacks, the network collapses faster, but for the number of avalanche nodes, under the degree-based attack, the number of the failed nodes is highest. When the nodes’ bearing capacity becomes large, the regularity of the network’s performances is not obvious. The findings can be applied to identify the vulnerable nodes in real networks such as wireless sensor networks and improve their robustness against different attacks.
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Sosio, Rosanna, Giovanni B. Crosta y Oldrich Hungr. "Numerical modeling of debris avalanche propagation from collapse of volcanic edifices". Landslides 9, n.º 3 (6 de noviembre de 2011): 315–34. http://dx.doi.org/10.1007/s10346-011-0302-8.
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Alfin, A. S., H. E. Wibowo y A. Harijoko. "Morphometric Characteristic and Distribution of Hummocky Hills in Debris Avalanche Deposit of Galunggung Volcano, West Java, Indonesia". IOP Conference Series: Earth and Environmental Science 1071, n.º 1 (1 de agosto de 2022): 012012. http://dx.doi.org/10.1088/1755-1315/1071/1/012012.
Resumen
Abstract Sector collapse of a volcanic body produces topography of horseshoe-shaped caldera incisions and a widespread hummocky hill resembling debris avalanche deposit. The study of morphometry, distribution, and the alignment of the hummocky hills is necessary to understand the source and deposition process of the debris-avalanche deposit. Galunggung volcano is, one of the volcanoes in Java Island, attributed with 7 km wide of caldera opens towards the east direction (N 135° E) where hummocky hills cover an area of ~32 km2. Morphometry of the hummocky hills is 500-700,000 m2 in size, elongation ratio of 1.3-3.9. Hummocky hills are distributed 0.5 to 20 km distance from the summit of the Galunggung volcano. The elongation orientation of the hummocky hills is deviated from the main flow direction forming various angles. We divide the deviation angle into parallel (0-45°) and perpendicular orientation (45-90°). The maximum size of the hummocky hills generally decreases towards increasing distance from the summit. These hills also show changes in alignment from perpendicular to parallel, suggesting a typical free flow pattern of debris-avalanche deposits.
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Milana, Juan Pablo y Philipp Geisler. "Forensic Geology Applied to Decipher the Landslide Dam Collapse and Outburst Flood of the Santa Cruz River (12 November 2005), San Juan, Argentina". GeoHazards 3, n.º 2 (12 de mayo de 2022): 252–76. http://dx.doi.org/10.3390/geohazards3020014.
Resumen
A well-known landslide dam that collapsed and generated a large outburst flood is used to show the importance of forensic geology analysis, which is the on-site multidisciplinary study of geohazards carries out as soon as possible after their occurrence; this study is focused on understanding the complete spectrum of all mechanisms that caused the disaster. Diagnostic elements of all natural processes fade with time, allowing for progressively divergent interpretations that may impact the appropriateness of potential mitigation actions, as we demonstrate. The multidisciplinary field control of the abrupt rupture of a natural dam on the Santa Cruz River on 12 November 2005, that released c. 37 million m3 of water and sediment, can radically change the interpretation of how this dam collapsed. In situ sedimentological, geomorphological and topographical analyses of the remains of the collapsed natural dam suggest it was built in two mass-wasting episodes instead of one, as previously interpreted, involving different slide materials. The first episode matches previous interpretations; a landslide that evolved into a rock avalanche, generating an initial dam of high stability due to its density, and observed angles of repose. This dam was not removed completely during the rupture, but rather suffered minor erosion at its top by the flood drag effect. The second episode is interpreted as a snow-dominated mixed avalanche, reaching much greater heights on the opposite side of the valley. This avalanche is estimated to be 85% snow, 8% debris and 7% ice-cemented permafrost fragments, and is evidenced by a thin residual deposit draping the valley sides, as most of this deposit melted out before any field control was undertaken. The growth of the lake level, along with the dam weight loss due to ablation, generated the hydrostatic instability that caused the floating of the central sector of this second dam and the violent evacuation of the water, similar to a jökulhlaup. This analysis explains the partial dam collapse, sudden water release and the preserved field evidence. This different interpretation suggests that the mitigation actions already taken can be improved and that monitoring systems are urgently needed. A rapid and professional assessment of any large-scale geohazard site would be the way to avoid interpretation discrepancies, and to guarantee that mitigation actions taken are adequate. Learning from this event may help decision makers to take better mitigation measures and potentially save lives.
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Blair, Terence C. "Form, facies, and depositional history of the North Long John rock avalanche, Owens Valley, California". Canadian Journal of Earth Sciences 36, n.º 6 (21 de junio de 1999): 855–70. http://dx.doi.org/10.1139/e99-024.
Resumen
The prehistoric but geomorphically pristine North Long John rock avalanche of the Inyo Mountains piedmont, California, formed by the catastrophic collapse and disintegration of a 500 × 1000 m range-front bedrock slab. This failure rapidly produced and transferred ~25 million cubic metres of new sediment to the piedmont, where it was deposited in a trough between two coalesced alluvial fans. The avalanche consists of nearly monolithologic (aplitic), unstratified, very angular, muddy, cobble, pebble gravel with boulders concentrated at the top and outer margins. The deposits are clast supported except in the lower central zone. Coarse clasts exhibit crackle-breccia fabric, and the voluminous equant pebbles are the disaggregated products of these clasts. The avalanche deposits are distributed in a U-shaped body with paired lateral levees 10-60 m high that extend 1560 m from the range front to a 108 m high distal snout. Each levee contains three segments that, along with the snout, overlap and extend progressively farther downslope from the inside of each other in a telescoped pattern. The most proximal deposits are the remnant sole sheared off where the avalanche intersected the piedmont, whereas the remainder was deposited as an ensuing grain flow. The radial alignment of the long axes of coarse clasts in the upper levees indicate that particle-particle interaction took place during flowage, and that clasts were pushed towards the margins. Part of the northern second levee borders a sharp and vertical, 10-18 m high scarp cleanly sliced through older fan deposits. This scarp was cut by the leading edge of the avalanche, which rapidly bulldozed away ~0.5 million cubic metres of fan deposits in the flow path. A southward cross-tilt resulted from the avalanche turning south due to interference with higher fan deposits on the north side. Friction from this interference restricted avalanche runout to 1.6 km, 25-33% of the distance predicted by empirical data from case studies lacking flow-path obstructions.
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Lala, Jonathan M., David R. Rounce y Daene C. McKinney. "Modeling the glacial lake outburst flood process chain in the Nepal Himalaya: reassessing Imja Tsho's hazard". Hydrology and Earth System Sciences 22, n.º 7 (13 de julio de 2018): 3721–37. http://dx.doi.org/10.5194/hess-22-3721-2018.
Resumen
Abstract. The Himalayas of South Asia are home to many glaciers that are retreating due to climate change and causing the formation of large glacial lakes in their absence. These lakes are held in place by naturally deposited moraine dams that are potentially unstable. Specifically, an impulse wave generated by an avalanche or landslide entering the lake can destabilize the moraine dam, thereby causing a catastrophic failure of the moraine and a glacial lake outburst flood (GLOF). Imja-Lhotse Shar Glacier is amongst the glaciers experiencing the highest rate of mass loss in the Mount Everest region, in part due to the expansion of Imja Tsho. A GLOF from this lake may have the potential to cause catastrophic damage to downstream villages, threatening both property and human life, which prompted the Nepali government to construct outlet works to lower the lake level. Therefore, it is essential to understand the processes that could trigger a flood and quantify the potential downstream impacts. The avalanche-induced GLOF process chain was modeled using the output of one component of the chain as input to the next. First, the volume and momentum of various avalanches entering the lake were calculated using Rapid Mass Movement Simulation (RAMMS). Next, the avalanche-induced waves were simulated using the Basic Simulation Environment for Computation of Environmental Flow and Natural Hazard Simulation (BASEMENT) model and validated with empirical equations to ensure the proper transfer of momentum from the avalanche to the lake. With BASEMENT, the ensuing moraine erosion and downstream flooding was modeled, which was used to generate hazard maps downstream. Moraine erosion was calculated for two geomorphologic models: one site-specific using field data and another worst-case based on past literature that is applicable to lakes in the greater region. Neither case resulted in flooding outside the river channel at downstream villages. The worst-case model resulted in some moraine erosion and increased channelization of the lake outlet, which yielded greater discharge downstream but no catastrophic collapse. The site-specific model generated similar results, but with very little erosion and a smaller downstream discharge. These results indicated that Imja Tsho is unlikely to produce a catastrophic GLOF due to an avalanche in the near future, although some hazard exists within the downstream river channel, necessitating continued monitoring of the lake. Furthermore, these models were designed for ease and flexibility such that local or national agency staff with reasonable training can apply them to model the GLOF process chain for other lakes in the region.
36
Bao, Yiding, Jianping Chen, Weifeng Zhang, Yuchao Li, Zhihai Li y Ni Du. "Effect of the Fracturing Degree of the Source Rock on Rock Avalanche River-Blocking Behavior Based on the Coupled Eulerian-Lagrangian Technique". Minerals 12, n.º 7 (18 de julio de 2022): 901. http://dx.doi.org/10.3390/min12070901.
Resumen
In this study, the effect of the fracturing degree of the source rock on rock avalanche river-blocking behavior was investigated. The study included the analysis of mass movement behavior, impulse wave behavior, and the formation of landslide dams. The study included a series of simulations of rock avalanche river-blocking based on the coupled Eulerian-Lagrangian (CEL) technique. Prior to the simulation, a water column collapse model was applied to validate the use of the CEL technique on fluid-structure interaction, and to calibrate the material parameters. The source rock in the rock avalanche simulation was cut by different groups of structural planes, with the number of 0 × 0 × 0, 1 × 1 × 1, 4 × 4 × 4, 9 × 9 × 9, 14 × 14 × 14, 19 × 19 × 19 in each dimension, respectively, to represent different fracturing degrees, on the premise of the same volume and shape of the source rock. The simulation results showed that the sliding mass exhibited structure stabilization, such that the structure of the sliding mass gradually stabilized to a steady status over time, in the mass movement process. The structure stabilization made the center of the sliding mass constantly decrease, and provided a higher speed of movement for the rock avalanches with higher fracturing degrees of the source rock. As for the impulse wave behavior, with the increase in the fracturing degree of the source rock, the maximum kinetic energy of the water decreased, and the maximum height and propagation speed of the impulse waves decreased, which indicated that the maximum height and the propagation speed of the impulse waves were positively correlated with the maximum kinetic energy of the water. In regard to the formation of the landslide dams, when the fracturing degree of the source rock was low, the shape of the landslide dam was very different. With the increase of the fracturing degree of the source rock, the shapes of the landslide dams stabilized, and varied slightly after the fracturing degree of the source rock reached a threshold value.
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Gaume, Johan, Alec van Herwijnen, Guillaume Chambon, Nander Wever y Jürg Schweizer. "Snow fracture in relation to slab avalanche release: critical state for the onset of crack propagation". Cryosphere 11, n.º 1 (27 de enero de 2017): 217–28. http://dx.doi.org/10.5194/tc-11-217-2017.
Resumen
Abstract. The failure of a weak snow layer buried below cohesive slab layers is a necessary, but insufficient, condition for the release of a dry-snow slab avalanche. The size of the crack in the weak layer must also exceed a critical length to propagate across a slope. In contrast to pioneering shear-based approaches, recent developments account for weak layer collapse and allow for better explaining typical observations of remote triggering from low-angle terrain. However, these new models predict a critical length for crack propagation that is almost independent of slope angle, a rather surprising and counterintuitive result. Based on discrete element simulations we propose a new analytical expression for the critical crack length. This new model reconciles past approaches by considering for the first time the complex interplay between slab elasticity and the mechanical behavior of the weak layer including its structural collapse. The crack begins to propagate when the stress induced by slab loading and deformation at the crack tip exceeds the limit given by the failure envelope of the weak layer. The model can reproduce crack propagation on low-angle terrain and the decrease in critical length with increasing slope angle as modeled in numerical experiments. The good agreement of our new model with extensive field data and the ease of implementation in the snow cover model SNOWPACK opens a promising prospect for improving avalanche forecasting.
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Rosendahl, Philipp L. y Philipp Weißgraeber. "Modeling snow slab avalanches caused by weak-layer failure – Part 1: Slabs on compliant and collapsible weak layers". Cryosphere 14, n.º 1 (17 de enero de 2020): 115–30. http://dx.doi.org/10.5194/tc-14-115-2020.
Resumen
Abstract. Dry-snow slab avalanche release is preceded by a fracture process within the snowpack. Recognizing weak-layer collapse as an integral part of the fracture process is crucial and explains phenomena such as whumpf sounds and remote triggering of avalanches from low-angle terrain. In this two-part work we propose a novel closed-form analytical model for a snowpack under skier loading and a mixed-mode failure criterion for the nucleation of weak-layer failure. In the first part of this two-part series we introduce a closed-form analytical model of a snowpack accounting for the deformable layer. Despite the importance of persistent weak layers for slab avalanche release, no simple analytical model considering weak-layer deformations is available. The proposed model provides deformations of the snow slab, weak-layer stresses and energy release rates of cracks within the weak layer. It generally applies to skier-loaded slopes as well as stability tests such as the propagation saw test. A validation with a numerical reference model shows very good agreement of the stress and energy release rate results in several parametric studies including analyses of the bridging effect and slope angle dependence. The proposed model is used to analyze 93 propagation saw tests. Computed weak-layer fracture toughness values are physically meaningful and in excellent agreement with finite element analyses. In the second part of the series (Rosendahl and Weißgraeber, 2020) we make use of the present mechanical model to establish a novel failure criterion crack nucleation in weak layers. The code used for the analyses in both parts is publicly available under https://github.com/2phi/weac (last access: 6 January 2020) (2phi, 2020).
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Eckstein, Jack T., Michael A. Carpenter y Ekhard K. H. Salje. "Ubiquity of avalanches: Crackling noise in kidney stones and porous materials". APL Materials 11, n.º 3 (1 de marzo de 2023): 031112. http://dx.doi.org/10.1063/5.0138123.
Resumen
Systematic advances in the resolution and analytical interpretation of acoustic emission (AE) spectroscopy have, over the last decade, allowed for extensions into novel fields. The same dynamic failure patterns, which have been identified in earthquakes, magnetism, and switching of ferroelastic and ferroelectric materials, are shown, in this paper, to be equally important in medicine, and minerals, in the geological context, to give just two examples. In the first application, we show that biological samples, i.e., kidney stones, can be analyzed with acoustic emission and related to the progression of mechanical avalanches. Discrepancies between strong and weak AE signals are shown to have separate avalanche exponents for a urate kidney stone, with evidence of slight multi-branching. It is proposed that investigations of this nature can be adopted to the field of medicine, and in the case of kidney stones, can provide a blueprint for selecting ideal combinations of energy and frequency to instigate their destruction. In a second example, porous geological material failure is shown to proceed equally in avalanches, and precursors to catastrophic failure can be detected via AE. Warning signs of impeding macroscopic collapse, e.g., in mining activities, show systematic evolution of energy exponents. Ultimately, this behavior is a result of geological processes, man-made bio-mineralization, or the burning of carbon inclusions, creating pores and holes, causing cracks, and accelerating their interactions.
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Pasquier, Mathieu, Marc Blancher, Grégoire Zen Ruffinen y Olivier Hugli. "Does Rescue Collapse Mandate a Paradigm Shift in the Field Management of Avalanche Victims?" High Altitude Medicine & Biology 16, n.º 2 (junio de 2015): 171–72. http://dx.doi.org/10.1089/ham.2015.0012.
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Bernard, Benjamin, Benjamin van Wyk de Vries, Diego Barba, Hervé Leyrit, Claude Robin, Samantha Alcaraz y Pablo Samaniego. "The Chimborazo sector collapse and debris avalanche: Deposit characteristics as evidence of emplacement mechanisms". Journal of Volcanology and Geothermal Research 176, n.º 1 (septiembre de 2008): 36–43. http://dx.doi.org/10.1016/j.jvolgeores.2008.03.012.
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Dufresne, Anja, Sergio Salinas y Claus Siebe. "Substrate deformation associated with the Jocotitlán edifice collapse and debris avalanche deposit, Central México". Journal of Volcanology and Geothermal Research 197, n.º 1-4 (noviembre de 2010): 133–48. http://dx.doi.org/10.1016/j.jvolgeores.2010.02.019.
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Linkov, Nikolay. "Calculation for the progressive collapse of the steel frame based on the shutdown of an element of the structural scheme". E3S Web of Conferences 389 (2023): 06023. http://dx.doi.org/10.1051/e3sconf/202338906023.
Resumen
Reliability of a building object - the ability of a building object perform the required functions during the estimated service life. In this case, the structure may experience a special limit state after exceeding the limit of the bearing capacity in the first and deformability in the second limit states, in which they do not fully comply with the functional requirements; further increase in loads and impacts leads to their destruction. The assumed initial local destruction implies the removal of a bearing structural element, simulating the loss of bearing capacity and stability, as well as leading to a change in the structural design of the structure. As a result of the damage received, a progressive avalanche collapse can occur in the form of the destruction of load-bearing building structures, leading to the collapse of the entire building or structure or its parts due to the initial local destruction.
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de' Michieli Vitturi, Mattia, Tomaso Esposti Ongaro, Giacomo Lari y Alvaro Aravena. "IMEX_SfloW2D 1.0: a depth-averaged numerical flow model for pyroclastic avalanches". Geoscientific Model Development 12, n.º 1 (1 de febrero de 2019): 581–95. http://dx.doi.org/10.5194/gmd-12-581-2019.
Resumen
Abstract. Pyroclastic avalanches are a type of granular flow generated at active volcanoes by different mechanisms, including the collapse of steep pyroclastic deposits (e.g., scoria and ash cones), fountaining during moderately explosive eruptions, and crumbling and gravitational collapse of lava domes. They represent end-members of gravity-driven pyroclastic flows characterized by relatively small volumes (less than about 1 Mm3) and relatively thin (1–10 m) layers at high particle concentration (10–50 vol %), manifesting strong topographic control. The simulation of their dynamics and mapping of their hazards pose several different problems to researchers and practitioners, mostly due to the complex and still poorly understood rheology of the polydisperse granular mixture and to the interaction with the complex natural three-dimensional topography, which often causes rapid rheological changes. In this paper, we present IMEX_SfloW2D, a depth-averaged flow model describing the granular mixture as a single-phase granular fluid. The model is formulated in absolute Cartesian coordinates (whereby the fluid flow equations are integrated along the direction of gravity) and can be solved over a topography described by a digital elevation model. The numerical discretization and solution algorithms are formulated to allow for a robust description of wet–dry conditions (thus allowing us to accurately track the front propagation) and an implicit solution to the nonlinear friction terms. Owing to these features, the model is able to reproduce steady solutions, such as the triggering and stopping phases of the flow, without the need for empirical conditions. Benchmark cases are discussed to verify the numerical code implementation and to demonstrate the main features of the new model. A preliminary application to the simulation of the 11 February pyroclastic avalanche at the Etna volcano (Italy) is finally presented. In the present formulation, a simple semi-empirical friction model (Voellmy–Salm rheology) is implemented. However, the modular structure of the code facilitates the implementation of more specific and calibrated rheological models for pyroclastic avalanches.
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Naranjo, José Antonio, Jorge Romero, Juan Pablo Contreras, Yuji Orihashi, Kevin Scott, Miguel Haller y Hirochika Sumino. "Rapid growth and catastrophic destruction events of Planchón Volcano, Southern Andes". Volcanica 7, n.º 1 (30 de enero de 2024): 21–49. http://dx.doi.org/10.30909/vol.07.01.2149.
Resumen
During the Late Pleistocene-to-Holocene, the mafic Planchón volcano (35.2 °S, Southern Andes) experienced two important destructive events: a sector collapse to the west and a multiphase explosive eruption transforming the east summit area. We provide new field and laboratory evidence, including geochemical, geochronologic, and geological-morphological analysis, to reconstruct the evolution, triggering mechanisms, and physical parameters of these events.The lateral collapse (48~ka BP) was mainly predisposed by a tectonically westward-inclined substratum and rapid edifice growth rates (0.3–0.48 km3 ka-1). The resulting Planchón-Teno debris avalanche became valley-confined traveling at c. 260 km h-1 up to 95 km distance and forming an 8.6 ± 1.3 km3 deposit. The resulting 4.1 km wide amphitheater was later destroyed at c. 7 ka BP by the multiphase Valenzuela phreatomagmatic eruptions, forming a c. 2.5 km diameter caldera. The case of the Planchón volcano warns that rapidly growing mafic volcanoes imply a substantial catastrophic hazard increase for the surrounding areas.
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Berthet-Rambaud, P., A. Limam, P. Roenelle, F. Rapin, J. M. Tacnet y J. Mazars. "Avalanche action on rigid structures: Back-analysis of Taconnaz deflective walls' collapse in February 1999". Cold Regions Science and Technology 47, n.º 1-2 (enero de 2007): 16–31. http://dx.doi.org/10.1016/j.coldregions.2006.08.004.
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Degtyarev, A. Ya. "Study of the Fundamental Causes Behind the Collapse of the Soviet Union is an Urgent Problem for Russian Science (Russian Federation Council)". Herald of the Russian Academy of Sciences 92, S1 (marzo de 2022): S57—S59. http://dx.doi.org/10.1134/s1019331622070024.
Resumen
AbstractAccording to the author, Soviet localization policy and the almost complete expulsion of Russians from the administrative apparatuses of the Union republics predetermined the avalanche-like sovereignization at the end of the 1980s–beginning of the 1990s. The factor that accelerated this process was the ill-conceived chaotic policy adopted by the leadership of the Central Committee of the Communist Party of the Soviet Union (CC CPSU) and the Politburo, headed by M.S. Gorbachev.
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Fadli, Adil y Arief Rijaluddin. "METODE PELAKSANAAN PONDASI BORE PILE PADA PEKERJAAN PENANGANAN LONGSORAN PROYEK PRESERVASI JALAN CIREBON – PALIMANAN – SUMEDANG". SEMINAR TEKNOLOGI MAJALENGKA (STIMA) 7 (8 de noviembre de 2023): 298–310. http://dx.doi.org/10.31949/stima.v7i0.853.
Resumen
Implementation of bore pile foundation on the Cirebon - Palimanan - Sumedang road Preservation Project is one of the work items for handling landslides which aims to strengthen the retaining wall structure from the load it will carry so that there is no shifting and settlement, the retaining wall structure was built due to the previous existing conditions has experienced a collapse so that a new retaining wall is planned. The foundation used in the construction of retaining walls, namely the bore pile foundation, is a type of deep foundation whose installation is carried out by first drilling the soil with a certain diameter using heavy equipment, bore pile machine until it reaches a predetermined depth, then the assembled steel frame is inserted. drill hole and the next step is casting. The purpose of this study is to find out how the process and method of implementing bore pile foundations in the avalanche handling work of the Cirebon - Palimanan - Sumedang Road Preservation Project. In the method of carrying out bore pile foundations for avalanche handling work on the Cirebon - Palimanan - Sumedang road preservation project, there are several stages of work including preparation, ironing, drilling, casting, and Test Pile.
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Moskalev, M. B. y M. V. Goriunov. "On the issue of regulating the stress-strain state of structures taking into account progressive collapse". Вестник гражданских инженеров 17, n.º 6 (2020): 70–76. http://dx.doi.org/10.23968/1999-5571-2020-17-6-70-76.
Resumen
The control of the stress-strain state of the structure using regulators allows creating unique structures that quickly respond to changes in the external environment, and, therefore, can be effectively used in all areas of construction. Due to the advancement of automation and information fast transmission means, these structures are going to become more and more relevant. The authors have analyzed the criteria for setting the regulators based on the arising forces in the truss rods, the removal of load in the given truss from the action of the regulators has been calculated, and disadvantages have been identified. The results obtained can be applied in the design of controlled structures to protect against avalanche collapse and ensure a proper stabilization of deformation and forces in trusses.
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Ding, Chao, Guangcai Feng, Lu Zhang, Qiang Shen, Zhiqiang Xiong y Mingsheng Liao. "The Precursory 3D Displacement Patterns and Their Implicit Collapse Mechanism of the Ice-Rock Avalanche Events Occurred in Sedongpu Basin Revealed by Optical and SAR Observations". Remote Sensing 15, n.º 11 (29 de mayo de 2023): 2818. http://dx.doi.org/10.3390/rs15112818.
Resumen
Quantifying the kinematic evolution patterns of mountain glaciers near Yarlung Tsanpo River performs a major role in evaluating the glacial instability and the secondary disasters. For the Sedongpu Basin near the Yarlung Tsanpo River Valley, the dramatic geomorphic landscape variations triggered by the ice-rock avalanche events were visually identified as the dominant texture deficiencies in time-series optical images. To improve the image correlation quality broken by these image texture deficiencies, the Landsat-8/Sentinel-2 optical images were divided into different groups, then a stepwise combination strategy was innovatively proposed to derive the glacier time-series displacement velocities in different temporal stages. The standard deviations (STD) of the optical measurements in the stable area maintained around 0.04 m/yr for the normalized displacement velocity and maintained from 0.6 to 1.7 m for the cumulative displacement time series. The obvious variations in glacier displacement velocity were identified before each collapse event. Subsequently, the offset-tracking procedures were performed on 7 Sentinel-1A Synthetic Aperture Radar (SAR) images to acquire the range and azimuth displacement velocities. To better reveal the dynamic mechanism of the glacier activity, the three-dimensional (3D) glacial displacement velocity was also derived by using optical and SAR results. The precipitation, temperature, and seismic activities were assumed as the main triggering factors of controlling the glacial dynamic mechanism and final collapse events. Additionally, the dynamic mechanism of the active glaciers in Sedongpu Basin conformed to a power law, which was limited by the changes of the internal stress friction force on the sliding base surface. The aim of this study is to shed a light on interpreting the precursory displacement patterns and their implicit failure mechanism of these ice-rock avalanche events with the conventional freely optical and SAR observations.