Journal articles on the topic 'Catastrophic melting'
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1
Kokelaar, Peter. "Friction melting, catastrophic dilation and breccia formation along caldera superfaults." Journal of the Geological Society 164, no. 4 (July 2007): 751–54. http://dx.doi.org/10.1144/0016-76492006-059.
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Grund, Brigid Sky, and Snehalata V. Huzurbazar. "RADIOCARBON DATING OF TECHNOLOGICAL TRANSITIONS: THE LATE HOLOCENE SHIFT FROM ATLATL TO BOW IN NORTHWESTERN SUBARCTIC CANADA – ERRATUM." American Antiquity 83, no. 1 (January 2018): 184. http://dx.doi.org/10.1017/aaq.2017.72.
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The author affiliations appearing in Grund and Huzurbazar (2017) contain errors. The correct affiliations for the authors are as follows: Brigid Sky Grund ▪ Anthropology Department, University of Wyoming, Department 3431, 1000 E. University Avenue, Laramie, Wyoming 82071-2001.Snehalata V. Huzurbazar ▪ Department of Biostatistics, West Virginia University, P.O. Box 9190, One Medical Center Drive, Morgantown WV 26506, USA.Additionally, the sentence on page 5 reading, “Catastrophic melting events create palimpsest the upper layers of ice (Meulendyk et al. 2012), potentially introducing taphonomic bias” inadvertently omitted two words. The correct sentence is “Catastrophic melting events create a palimpsest in the upper layers of ice, potentially introducing taphonomic bias.”The publisher apologizes for these errors.
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Karasev, Valentin Petrovich, Sergey Vladimirovich Ryaboshuk, Pavel Valer'evich Kovalev, and Vitaliy Kulikov. "Phosphorus Removal Options at Induction Melting of Steel." Key Engineering Materials 822 (September 2019): 30–36. http://dx.doi.org/10.4028/www.scientific.net/kem.822.30.
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The main aspects of effective dephosphorization of steel under conditions of induction melting are presented. Regularities of scale growth on the surface of iron, as well as the conditions of its catastrophic oxidation, are considered. An industrial experiment was conducted to remove phosphorus from steel intended for brake discs.
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Bengus(a),, V. Z., E. D. Tabachnikova(a),, S. E. Shuinilin(a),, K. Csach(b),, P. Duhaj(c),, and J. Mishkuf(b),. "Local Melting in the Catastrophic Shear Band of Amorphous Alloy Ribbons." Journal of the Mechanical Behavior of Materials 5, no. 3 (June 1994): 315–24. http://dx.doi.org/10.1515/jmbm.1994.5.3.315.
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MacAyeal, Douglas R., and Olga V. Sergienko. "The flexural dynamics of melting ice shelves." Annals of Glaciology 54, no. 63 (2013): 1–10. http://dx.doi.org/10.3189/2013aog63a256.
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AbstractA conspicuous precursor of catastrophic ice-shelf break-up along the Antarctic Peninsula, reported widely in the literature, is the gradual increase in surface melting and consequent proliferation of supraglacial lakes and dolines. Here we present analytical and numerical solutions for the flexure stresses within an ice shelf covered by lakes and dolines, both isolated and arrayed. We conclude that surface water promotes ice-shelf instability in two ways: (1) by water-assisted crevasse penetration, as previously noted, and (2) by the inducement of strong tensile flexure stresses (exceeding background spreading stress by 10–100 times) in response to surface water mass loads and ‘hydrostatic rebound’ occurring when meltwater lakes drain.
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Sung, Si Young, and Young Jig Kim. "Melting and Casting of Titanium Alloys." Materials Science Forum 539-543 (March 2007): 3601–6. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.3601.
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Over the past decades, a large number of researchers have been trying titanium alloys in an attempt to combine most of their advantages, such as high specific yield strength, good corrosion resistance, excellent fatigue property and biocompatibility by casting route. However, the wide use of titanium alloys casting has been limited, since it is considered as only a near net shape forming process in titanium alloys due to the catastrophic reactivity of molten states, the alpha-case formations and the casting defects. In order to maximize the unique property of titanium alloys casting which are comparable to wrought products and quite often superior, it is necessary to take a close examination of titanium alloys casting procedure. Therefore, the merits and demerits of various melting devices, pouring methods and mold materials will be addressed with regard to improving titanium alloys casting.
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Akstinas, Vytautas, Diana Meilutytė-Lukauskienė, Jūratė Kriaučiūnienė, and Diana Šarauskienė. "Features and causes of catastrophic floods in the Nemunas River basin." Hydrology Research 51, no. 2 (July 18, 2019): 308–21. http://dx.doi.org/10.2166/nh.2019.147.
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Abstract The Nemunas River basin falls within the territories of five different countries – Belarus, Lithuania, Russia, Poland and Latvia. In general, the beginning of spring floods highly depends on rapid rise of air temperature, heavy precipitation and sudden snow melting in the analysed basin. In this paper, the conditions of formation and consequences of two catastrophic floods in 1958 and 1979 in the Nemunas River basin were studied regarding the hydrometeorological parameters (maximum snow water equivalent before the beginning of flood and precipitation amount during the flood) as well as runoff coefficients for each selected catastrophic flood. Differences between the main drivers and evolution of these floods were analysed. Spatial distribution of maximum snow water equivalent and precipitation, as well as runoff coefficient in different parts of the river basin, were identified as having the most significant impact on the formation of the studied catastrophic floods.
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Blown, Iain, and Michael Church. "Catastrophic lake drainage within the Homathko River basin, British Columbia." Canadian Geotechnical Journal 22, no. 4 (November 1, 1985): 551–63. http://dx.doi.org/10.1139/t85-075.
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Three distinct phenomena related to sudden lake drainage, which occurred in a restricted area within the southern Coast Mountains of British Columbia, are described: (i) moraine breaching by solitary wave action following an icefall into a lake; (ii) failure of a glacier ice dam by flotation and melting to produce a ‘glacier outburst’ flood or ‘jökulhlaup;’ (iii) debris torrent following a moraine breach. The possibility for a fourth failure phenomenon: moraine failure by piping, is discussed. A first attempt to develop practical hazard evaluation methods before the event, which relies on simple scale relations or index relations developed from experience of events elsewhere, is presented. Key words: dam break, debris flow, hazard evaluation, jökulhlaup, lakes, lake drainage.
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Gladish, Carl V., David M. Holland, Paul R. Holland, and Stephen F. Price. "Ice-shelf basal channels in a coupled ice/ocean model." Journal of Glaciology 58, no. 212 (2012): 1227–44. http://dx.doi.org/10.3189/2012jog12j003.
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AbstractA numerical model for an interacting ice shelf and ocean is presented in which the ice- shelf base exhibits a channelized morphology similar to that observed beneath Petermann Gletscher’s (Greenland) floating ice shelf. Channels are initiated by irregularities in the ice along the grounding line and then enlarged by ocean melting. To a first approximation, spatially variable basal melting seaward of the grounding line acts as a steel-rule die or a stencil, imparting a channelized form to the ice base as it passes by. Ocean circulation in the region of high melt is inertial in the along-channel direction and geostrophically balanced in the transverse direction. Melt rates depend on the wavelength of imposed variations in ice thickness where it enters the shelf, with shorter wavelengths reducing overall melting. Petermann Gletscher’s narrow basal channels may therefore act to preserve the ice shelf against excessive melting. Overall melting in the model increases for a warming of the subsurface water. The same sensitivity holds for very slight cooling, but for cooling of a few tenths of a degree a reorganization of the spatial pattern of melting leads, surprisingly, to catastrophic thinning of the ice shelf 12 km from the grounding line. Subglacial discharge of fresh water along the grounding line increases overall melting. The eventual steady state depends on when discharge is initiated in the transient history of the ice, showing that multiple steady states of the coupled system exist in general.
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Ahmad, Hafiz Haroon, Farhan Saleem, and Hania Arif. "Evaluation of catastrophic global warming due to coal combustion." Vol 3 Issue 4 3, no. 4 (December 31, 2021): 198–207. http://dx.doi.org/10.33411/ijist/2021030406.
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Coal is a carbon containing non-renewable fossil fuel and one of the major contributors of climate change and global warming. We used TANSO FTS instrument in order to obtain the level of atmospheric carbon dioxide through datasets obtained from GOSAT satellite. GIOVANNI was also used to obtain atmospheric concentration of various gases. Burning of coal causes emission of greenhouse gases (GHG) and black carbon (BC) in atmosphere which are responsible for nearly 0.3°C of 1°C rise in temperature. The annual average value of carbon emission for the year 2010 and 2019 is 388.4 ppm and 409 ppm respectively. Since the pre-industrial times CO2 concentrations have increased up to100 PPM (36%) in the last two and a half centuries (250 years).In South Asia Dhaka has the worst quality of air as CO2 concentration (6.7%) is higher than the country’s GDP (5.25%) and energy consumption (4.77%). While an increasing trend GHG has been observed in Lahore up to 5.5 %. This study concludes that the high concentration of carbon dioxide in atmosphere is responsible for average rise of 1.2 °C temperature annually. This temperature rise can lead to adverse climatic conditions i.e., melting of glaciers which will consequently rise the sea level various landmasses may disappear by 2050.
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Kendrick, J. E., Y. Lavallée, K. U. Hess, S. De Angelis, A. Ferk, H. E. Gaunt, P. G. Meredith, D. B. Dingwell, and R. Leonhardt. "Seismogenic frictional melting in the magmatic column." Solid Earth 5, no. 1 (April 9, 2014): 199–208. http://dx.doi.org/10.5194/se-5-199-2014.
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Abstract. Lava dome eruptions subjected to high extrusion rates commonly evolve from endogenous to exogenous growth and limits to their structural stability hold catastrophic potential as explosive eruption triggers. In the conduit, strain localisation in magma, accompanied by seismogenic failure, marks the onset of brittle magma ascent dynamics. The rock record of exogenous dome structures preserves vestiges of cataclastic processes and thermal anomalies, key to unravelling subsurface processes. Here, a combined structural, thermal and magnetic investigation of a shear band crosscutting a large block erupted in 2010 at Soufrière Hills volcano (SHV) reveals evidence of faulting and frictional melting within the magmatic column. The mineralogy of this pseudotachylyte vein offers confirmation of complete recrystallisation, altering the structure, porosity and permeability of the material, and the magnetic signature typifies local electric currents in faults. Such melting events may be linked to the step-wise extrusion of magma accompanied by repetitive long-period (LP) drumbeat seismicity at SHV. Frictional melting of Soufrière Hills andesite in a high velocity rotary shear apparatus highlights the small slip distances (< 15 cm) thought to be required to bring 800 °C magma to melting point at upper conduit stress conditions (10 MPa). We conclude that frictional melting is a common consequence of seismogenic magma fracture during dome building eruptions and that it may govern the ascent of magma in the upper conduit.
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Saltzman, Barry, and Mikhail Ya Verbitsky. "Heinrich-scale surge oscillations as an internal property of ice sheets." Annals of Glaciology 23 (1996): 348–51. http://dx.doi.org/10.3189/s0260305500013628.
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A dynamical model governing the variations of ice-sheet volume, basal-water amount and ice-surge flux has been formulated in its simplest form, based on fundamental thermomechanical properties of ice sheets governing the basal-melting process. This model includes the effects of the geothermal flux, internal thermal advection and basal friction, the latter two factors being particularly important in regulating the bottom temperature and bringing it to the melting point, i.e. to a state vulnerable to catastrophic ice surges. It is shown that, for certain values of the unknown rate constants, such a model can exhibit oscillations on roughly the same scale as observed Heinrich events, even when external climatic changes are neglected, which would support the view that such events are an internal properly of ice sheets.
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Saltzman, Barry, and Mikhail Ya Verbitsky. "Heinrich-scale surge oscillations as an internal property of ice sheets." Annals of Glaciology 23 (1996): 348–51. http://dx.doi.org/10.1017/s0260305500013628.
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A dynamical model governing the variations of ice-sheet volume, basal-water amount and ice-surge flux has been formulated in its simplest form, based on fundamental thermomechanical properties of ice sheets governing the basal-melting process. This model includes the effects of the geothermal flux, internal thermal advection and basal friction, the latter two factors being particularly important in regulating the bottom temperature and bringing it to the melting point, i.e. to a state vulnerable to catastrophic ice surges. It is shown that, for certain values of the unknown rate constants, such a model can exhibit oscillations on roughly the same scale as observed Heinrich events, even when external climatic changes are neglected, which would support the view that such events are an internal properly of ice sheets.
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Han, Zheng, and Yi Li. "Cooperative shear and catastrophic fracture of bulk metallic glasses from a shear-band instability perspective." Journal of Materials Research 24, no. 12 (December 2009): 3620–27. http://dx.doi.org/10.1557/jmr.2009.0442.
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The morphology of the fracture surfaces of a bulk metallic glass (BMG) tested under compression was systematically studied. Experimental results showed that the fracture surface always comprises two kinds of zones, starting with a relatively smooth zone followed by the second zone with vein patterns. It implies strongly that the plastic deformation of BMGs always starts with a cooperative shear. The following catastrophic fracture characterized by the vein patterns may or may not occur, depending on the magnitude of this shear, which is controlled by the sample size and machine stiffness. This phenomenon was interpreted based on the temperature rise resulting from the work done during the cooperative shear. It revealed that for small samples, the shear is so small that the temperature increase is insignificant, accounting for the extensive serrated flow, while the temperature increase in samples beyond a critical size is sufficiently high so that the temperatures are higher than the glass transition temperature or even the melting temperature, leading to catastrophic fracture.
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Kendrick, J. E., Y. Lavallée, K. U. Hess, S. De Angelis, A. Ferk, H. E. Gaunt, D. B. Dingwell, and R. Leonhardt. "Seismogenic frictional melting in the magmatic column." Solid Earth Discussions 5, no. 2 (October 16, 2013): 1659–86. http://dx.doi.org/10.5194/sed-5-1659-2013.
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Abstract. Lava dome eruptions subjected to high extrusion rates commonly evolve from endogenous to exogenous growth and limits to their structural stability hold catastrophic potential as explosive eruption triggers. In the conduit, strain localisation in magma, accompanied by seismogenic failure, marks the onset of brittle magma ascent dynamics. The rock record of exogenous dome structures preserves vestiges of cataclastic processes (Cashman et al., 2008; Kennedy and Russell, 2011) and of thermal anomalies (Kendrick et al., 2012), key to unravelling subsurface processes. Here, a combined structural, thermal and magnetic investigation of a shear band crosscutting a large block erupted in 2010 at Soufrière Hills volcano (SHV) reveals evidence of faulting and frictional melting within the magmatic column. The mineralogy of this pseudotachylyte vein offers confirmation of complete recrystallisation with an isothermal remanent magnetisation signature that typifies local electric currents in faults. The pseudotachylyte presents an impermeable barrier, which is thought to have influenced the degassing pathway. Such melting events may be linked to the step-wise extrusion of magma accompanied by repetitive long-period (LP) drumbeat seismicity at SHV (Neuberg et al., 2006). Frictional melting of SHV andesite in a high velocity rotary shear apparatus highlights the small slip distances (< 15 cm) required to bring 800 °C magma to melting point at upper conduit stress conditions (10 MPa). We conclude that frictional melting is an inevitable consequence of seismogenic, conduit-dwelling magma fracture during dome building eruptions and that it may have an important influence on magma ascent dynamics.
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Lupiano, Valeria, Paolo Catelan, Claudia R. Calidonna, Francesco Chidichimo, Gino M. Crisci, Valeria Rago, Salvatore Straface, and Salvatore Di Gregorio. "LLUNPIY Simulations of the 1877 Northward Catastrophic Lahars of Cotopaxi Volcano (Ecuador) for a Contribution to Forecasting the Hazards." Geosciences 11, no. 2 (February 12, 2021): 81. http://dx.doi.org/10.3390/geosciences11020081.
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LLUNPIY (lahar modeling by local rules based on an underlying pick of yoked processes, from the Quechua word “llunp’iy“, meaning flood) is a cellular automata (CA) model that simulates primary and secondary lahars, here applied to replicate those that occurred during the huge 1877 Cotopaxi Volcano eruption. The lahars flowing down the southwestern flanks of the volcano were already satisfactorily simulated in previous investigations of ours, assuming two possible different triggering mechanisms, i.e., the sudden and homogeneous melting of the summit ice and snow cap due to pyroclastic flows and the melting of the glacier parts hit by free-falling pyroclastic bombs after being upwardly ejected during the volcanic eruption. In a similar fashion, we apply here the CA LLUNPIY model to simulate the 1877 lahars sprawling out the Cotopaxi northern slopes and eventually impacting densely populated areas. Our preliminary results indicate that several important public infrastructures (among them the regional potable water supply system) and the Valle de Los Chillos and other Quito suburban areas might be devastated by northward-bound lahars, should a catastrophic Cotopaxi eruption comparable to the 1877 one occur in the near future.
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Klimeš, J., I. Baroň, T. Pánek, T. Kosačík, J. Burda, F. Kresta, and J. Hradecký. "Investigation of recent catastrophic landslides in the flysch belt of Outer Western Carpathians (Czech Republic): progress towards better hazard assessment." Natural Hazards and Earth System Sciences 9, no. 1 (February 13, 2009): 119–28. http://dx.doi.org/10.5194/nhess-9-119-2009.
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Abstract. Rapid snow melting and intense precipitation triggered and reactivated tens of mostly shallow landslides in the eastern part of the Czech Republic at the turn of March and April 2006. This area is build up by highly fractured flysch rock units with variable content of sandstones and claystones. The landslide complex at Hluboče (Brumov-Bylnice town) is composed of shallow translational (up to 10 m thick) as well as deep-seated (up to 20 m thick) rotational landslides, which generated a catastrophic earthflow at their toe. This earthflow destroyed three buildings, the access road and caused total loss of about 350 000 EUR. Detailed field investigation, review of the archive sources and interviewing of local inhabitants allowed brief description of slope movement history prior the catastrophic event as well as detailed reconstruction of slope failure mechanisms during the main movement activity (3–4 April 2006). This information, along with the detailed description of the passive as well as active causative factors (structural and morphologic settings) can contribute towards better identification of potentially dangerous slope failures in the study region.
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Holland, P. R., A. Brisbourne, H. F. J. Corr, D. McGrath, K. Purdon, J. Paden, H. A. Fricker, F. S. Paolo, and A. H. Fleming. "Atmospheric and oceanic forcing of Larsen C Ice Shelf thinning." Cryosphere Discussions 9, no. 1 (January 13, 2015): 251–99. http://dx.doi.org/10.5194/tcd-9-251-2015.
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Abstract. The catastrophic collapses of Larsen A and B ice shelves on the eastern Antarctic Peninsula have caused their tributary glaciers to accelerate, contributing to sea-level rise and freshening the Antarctic Bottom Water formed nearby. The surface of Larsen C Ice Shelf (LCIS), the largest ice shelf on the peninsula, is lowering. This could be caused by unbalanced ocean melting (ice loss) or enhanced firn melting and compaction (englacial air loss). Using a novel method to analyse eight radar surveys, this study derives separate estimates of ice and air thickness changes during a 15 year period. The uncertainties are considerable, but the primary estimate is that the surveyed lowering (0.066 ± 0.017 m yr−1) is caused by both ice loss (0.28 ± 0.18 m yr−1) and firn air loss (0.037 ± 0.026 m yr−1). Though the ice loss is much larger, ice and air loss contribute approximately equally to the lowering. The ice loss could be explained by high basal melting and/or ice divergence, and the air loss by low surface accumulation or high surface melting and/or compaction. The primary estimate therefore requires that at least two forcings caused the surveyed lowering. Mechanisms are discussed by which LCIS stability could be compromised in future, suggesting destabilisation timescales of a few centuries. The most rapid pathways to collapse are offered by a flow perturbation arising from the ungrounding of LCIS from Bawden Ice Rise, or ice-front retreat past a "compressive arch" in strain rates.
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Sato, Tatsuru, and Ralf Greve. "Sensitivity experiments for the Antarctic ice sheet with varied sub-ice-shelf melting rates." Annals of Glaciology 53, no. 60 (2012): 221–28. http://dx.doi.org/10.3189/2012aog60a042.
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AbstractIce-sheet modelling is an important tool for predicting the possible response of ice sheets to climate change in the past and future. An established ice-sheet model is SICOPOLIS (SImulation COde for POLythermal Ice Sheets), and for this study the previously grounded-ice-only model was complemented by an ice-shelf module. The new version of SICOPOLIS is applied to the Antarctic ice sheet, driven by standard forcings defined by the SeaRISE (Sea-level Response to Ice Sheet Evolution) community effort. A crucial point for simulations into the future is to obtain reasonable initial conditions by a palaeoclimatic spin-up, which we carry out over 125 000 years from the Eemian until today. We then carry out a set of experiments for 500 years into the future, in which the surface temperature and precipitation are kept at their present-day distributions, while sub-ice-shelf melting rates between 0 and 200 ma–1 are applied. These simulations show a significant, but not catastrophic, sensitivity of the ice sheet. Grounded-ice volumes decrease with increasing melting rates, and the spread of the results from the zero to the maximum melting case is ~0.65ms.l.e. (metres sea-level equivalent) after 100 years and ~2.25ms.l.e. after 500 years.
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Rodríguez, Carmen, Antonio Castro, Daniel Gómez-Frutos, Gabriel Gutiérrez-Alonso, M. Francisco Pereira, and Carlos Fernández. "The unique Cambro-Ordovician silicic large igneous province of NW Gondwana: Catastrophic melting of a thinned crust." Gondwana Research 106 (June 2022): 164–73. http://dx.doi.org/10.1016/j.gr.2022.01.011.
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Holland, P. R., A. Brisbourne, H. F. J. Corr, D. McGrath, K. Purdon, J. Paden, H. A. Fricker, F. S. Paolo, and A. H. Fleming. "Oceanic and atmospheric forcing of Larsen C Ice-Shelf thinning." Cryosphere 9, no. 3 (May 13, 2015): 1005–24. http://dx.doi.org/10.5194/tc-9-1005-2015.
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Abstract. The catastrophic collapses of Larsen A and B ice shelves on the eastern Antarctic Peninsula have caused their tributary glaciers to accelerate, contributing to sea-level rise and freshening the Antarctic Bottom Water formed nearby. The surface of Larsen C Ice Shelf (LCIS), the largest ice shelf on the peninsula, is lowering. This could be caused by unbalanced ocean melting (ice loss) or enhanced firn melting and compaction (englacial air loss). Using a novel method to analyse eight radar surveys, this study derives separate estimates of ice and air thickness changes during a 15-year period. The uncertainties are considerable, but the primary estimate is that the surveyed lowering (0.066 ± 0.017 m yr−1) is caused by both ice loss (0.28 ± 0.18 m yr−1) and firn-air loss (0.037 ± 0.026 m yr−1). The ice loss is much larger than the air loss, but both contribute approximately equally to the lowering because the ice is floating. The ice loss could be explained by high basal melting and/or ice divergence, and the air loss by low surface accumulation or high surface melting and/or compaction. The primary estimate therefore requires that at least two forcings caused the surveyed lowering. Mechanisms are discussed by which LCIS stability could be compromised in the future. The most rapid pathways to collapse are offered by the ungrounding of LCIS from Bawden Ice Rise or ice-front retreat past a "compressive arch" in strain rates. Recent evidence suggests that either mechanism could pose an imminent risk.
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Nagai, Hiroto, Manabu Watanabe, Naoya Tomii, Takeo Tadono, and Shinichi Suzuki. "Multiple remote-sensing assessment of the catastrophic collapse in Langtang Valley induced by the 2015 Gorkha earthquake." Natural Hazards and Earth System Sciences 17, no. 11 (November 13, 2017): 1907–21. http://dx.doi.org/10.5194/nhess-17-1907-2017.
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Abstract. The main shock of the 2015 Gorkha Earthquake in Nepal induced numerous avalanches, rockfalls, and landslides in Himalayan mountain regions. A major village in the Langtang Valley was destroyed and numerous people were victims of a catastrophic avalanche event, which consisted of snow, ice, rock, and blast wind. Understanding the hazard process mainly depends on limited witness accounts, interviews, and an in situ survey after a monsoon season. To record the immediate situation and to understand the deposition process, we performed an assessment by means of satellite-based observations carried out no later than 2 weeks after the event. The avalanche-induced sediment deposition was delineated with the calculation of decreasing coherence and visual interpretation of amplitude images acquired from the Phased Array-type L-band Synthetic Aperture Radar-2 (PALSAR-2). These outline areas are highly consistent with that delineated from a high-resolution optical image of WorldView-3 (WV-3). The delineated sediment areas were estimated as 0.63 km2 (PALSAR-2 coherence calculation), 0.73 km2 (PALSAR-2 visual interpretation), and 0.88 km2 (WV-3). In the WV-3 image, surface features were classified into 10 groups. Our analysis suggests that the avalanche event contained a sequence of (1) a fast splashing body with an air blast, (2) a huge, flowing muddy mass, (3) less mass flowing from another source, (4) a smaller amount of splashing and flowing mass, and (5) splashing mass without flowing on the east and west sides. By means of satellite-derived pre- and post-event digital surface models, differences in the surface altitudes of the collapse events estimated the total volume of the sediments as 5.51 ± 0.09 × 106 m3, the largest mass of which are distributed along the river floor and a tributary water stream. These findings contribute to detailed numerical simulation of the avalanche sequences and source identification; furthermore, altitude measurements after ice and snow melting would reveal a contained volume of melting ice and snow.
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Singh, R., D. Siingh, S. A. Gokani, P. S. Buchunde, R. P. Singh, and A. K. Singh. "Brief Communication: Climate, topographical and meteorological investigation of the 16–17 June 2013 Kedarnath (India) disaster causes." Natural Hazards and Earth System Sciences Discussions 3, no. 2 (February 3, 2015): 941–53. http://dx.doi.org/10.5194/nhessd-3-941-2015.
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Abstract. The devastating episode (17–18 June 2013) at Kedarnath (Uttrakhand, India) caused huge loss of lives and physical/material wealth. To understand this catastrophic event, rainfall/convective data and associated climate meteorological parameters are investigated. Low pressure zone with very high cloud cover (60–90%), and relative humidity (70–100%) associated with low (< 4 m s−1) wind velocity over Kedarnath region during 15–17 June are observed. The cause of disaster seems to be the heavy and continuous rainfall associated with snow melting and over flooding/collapse of the Chorabari Lake, located upstream. Monsoon advancement was much faster due to the presence of convectively active phase of the Madden Julian Oscillation.
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Salahuddin, Maria, Mirza Naseer Ahmed, and Rashida Sultana. "Mapping Flood Risk Assessment by Remote Sensing in District Chiniot, Pakistan." International Journal of Economic and Environmental Geology 11, no. 2 (September 25, 2020): 61–64. http://dx.doi.org/10.46660/ijeeg.vol11.iss2.2020.447.
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A flood is a catastrophic event of natural origin which involves exposure of human population, infrastructure, and resources. Heavy rainfall in river catchments, snow melting in monsoon season, inadequate drainage networks, water overflowing from the main drainage channels, conversion of natural vegetation, agricultural land, and wetlands due to urbanization are the core reasons of floods. Whereas, climate change has made the condition worse and increases the frequency of the floods. Asia consists approximately one-fifth of the earth's land area with half of the world's population living in this continent. As natural disasters increased around the world, Asian countries also continued to experience hazard events especially from 1994 to 2004, when nearly 60,000 people were killed in floods (Arambepola, 2009).
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Hu, Yong, Jinfu Li, Tao Lin, and Yaohe Zhou. "Plasticity improvement of Zr55Al10Ni5Cu30 bulk metallic glass by remelting master alloy ingots." Journal of Materials Research 24, no. 12 (December 2009): 3590–95. http://dx.doi.org/10.1557/jmr.2009.0430.
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The effect of repeated melting of master alloy ingots on the bending properties of Zr55Al10Ni5Cu30 bulk metallic glass (BMG) was investigated. The bending plasticity of Zr55Al10Ni5Cu30 BMG was found to be improved with the increased remelting times. When remelted 10 times, the BMG sample cast from the master alloy ingot undergoes bending, but it does not fracture even though the bending angle increases to 100°; the maximum bending stress and elastic strain remain almost constant. The bending plasticity improvement may be attributed to the fact that the increased remelting times result in more free volume and more disorder and homogeneous microstructure in the BMG, which favors the initial nucleation of profuse shear bands and reduces the probability of catastrophic fracture.
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Barbey, Pierre, Arnaud Villaros, Christian Marignac, and Jean-Marc Montel. "Multiphase melting, magma emplacement and P-T-time path in late-collisional context: the Velay example (Massif Central, France)." Bulletin de la Société Géologique de France 186, no. 2-3 (2015): 93–116. http://dx.doi.org/10.2113/gssgfbull.186.2-3.93.
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AbstractThe West European Variscan chain is a remarkable illustration of how partial melting marks out the geodynamic evolution of mountain belt through time. Here, we focus on the Late Carboniferous melting events reported in the southeastern French Massif Central (Velay dome), with emphasis on the modes of partial melting, relationships between partial melting and magma emplacement, transition between the melting episodes and related P-T-t path. Following nappe stacking events under medium pressure/temperature conditions (M1 and M2 events), three melting events are identified in the southern envelope of the Velay dome. A first melting episode (M3 event) occurred within the biotite stability field at 325–315 Ma (T ≈ 720°C and P = 0.5–0.6 GPa). It led to the complete disappearance of muscovite and to the formation of migmatites consisting of biotite ± sillimanite melanosome and of granitic/tonalitic leucosomes depending on protolith composition. It is interpreted as the result of internal heating mainly linked to decay of heat producing elements accumulated in a thickened crust. It resulted in the formation of a partially molten middle crust with decoupling between the lower and upper crust, late-collisional extension and crustal thinning.The second episode of melting (M4 event) occurred at ca. 304 Ma (T 800°C and P 0.4 GPa), synchronously with emplacement of the Velay granites and growth of the dome. It led to the breakdown of biotite and growth of cordierite (locally garnet or tourmaline), with formation of diatexites and heterogeneous granites. This high-T event synchronous with crustal extension is considered to result from intrusion of hot mantle-derived and lower crustal magmas triggering catastrophic melting in the middle crust. This event ends with local retrograde hydrous melting within the stability field of biotite close to the solidus in response to local input of water during temperature drop in the late stage of emplacement of the Velay dome.The last evidence of melting in this area (M5 event) corresponds to emplacement of late granites generated under conditions estimated at ≈850°C and 0.4–0.6 GPa. They may have been generated from melting of specific lithologies triggered by injection of mafic magmas. These granites emplaced in a partly cooled crust (medium-grade conditions). The emplacement age of these granites is not well constrained (305–295 Ma) though they clearly post-date the Velay granites.The melting episodes in the Velay area and generation of granites appear to correspond to the conjunction between (i) the effects of collision-related crust thickening and (ii) those related to slab break off and asthenospheric mantle decompression melting. The driving process is mainly the internal radiogenic heat in a first stage, relayed by the propagation of a thermal anomaly initially located in the lower crust (M3 event), but which subsequently rose to the middle and upper crustal levels through magma transfer (M4 event). Overall, the Velay example is a remarkable illustration of the progressive dehydration and sterilisation of a thickened crustal segment. It documents how large amounts of granitic magmas can be produced at shallow crustal levels in relation to the injection of mantle-derived magmas.
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Roos, Stefan, Carlos Botero, Jonas Danvind, Andrei Koptioug, and Lars-Erik Rännar. "Macro- and Micromechanical Behavior of 316LN Lattice Structures Manufactured by Electron Beam Melting." Journal of Materials Engineering and Performance 28, no. 12 (November 27, 2019): 7290–301. http://dx.doi.org/10.1007/s11665-019-04484-3.
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AbstractThis work focuses on the possibility of processing stainless steel 316LN powder into lightweight structures using electron beam melting and investigates mechanical and microstructural properties in the material of processed components. Lattice structures conforming to ISO13314:2011 were manufactured using varying process parameters. Microstructure was examined using a scanning electron microscope. Compression testing was used to understand the effect of process parameters on the lattice mechanical properties, and nanoindentation was used to determine the material hardness. Lattices manufactured from 316L using EBM show smooth compression characteristics without collapsing layers and shear planes. The material has uniform hardness in strut shear planes, a microstructure resembling that of solid 316LN material but with significantly finer grain size, although slightly coarser sub-grain size. Grains appear to be growing along the lattice struts (e.g., along the heat transfer direction) and not in the build direction. Energy-dispersive x-ray spectroscopy analysis reveals boundary precipitates with increased levels of chromium, molybdenum and silicon. Studies clearly show that the 316LN grains in the material microstructure are elongated along the dominating heat transfer paths, which may or may not coincide with the build direction. Lattices made from a relatively ductile material, like 316LN, are much less susceptible to catastrophic collapse and show an extended range of elastic and plastic deformation. Tests indicate that EBM process for 316LN is stable allowing for both solid and lightweight (lattice) structures.
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Мясникова, Л. П., В. Ф. Дроботько, А. П. Борзенко, Ю. М. Бойко, В. А. Марихин, С. A. Терехов, and М. А. Яговкина. "Поиск оптимальных условий монолитизации реакторного порошка сверхвысокомолекулярного полиэтилена." Физика твердого тела 63, no. 11 (2021): 1942. http://dx.doi.org/10.21883/ftt.2021.11.51601.164.
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In order to clarify the possibility of sintering reactor powders of ultra-high molecular weight polyethylene under pressure at a temperature higher than its equilibrium melting point at atmospheric pressure (T0m) without catastrophic changes in the internal structure of particles, a comparative WAXS analysis was carried out of the samples sintered below (T <T0m) and above (T> T0m) this temperature and cooled under different conditions. A multifunctional structural analysis of the X-ray scattering curves recorded in the Bragg-Brentano mode on a 2D Phaser Bruker diffractometer from UHMWPE reactor powders sintered under different conditions was carried out, and the crystallite sizes were calculated. It was found that an increase in the sintering temperature above T0m does not significantly change the crystal structure of the polymer, and the precursors produced can be used for further orientational hardening.
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Weidick, A., and H. H. Thomsen. "A decade of glacier investigations for utilisation of Greenland hydropower." Rapport Grønlands Geologiske Undersøgelse 128 (December 31, 1986): 157–69. http://dx.doi.org/10.34194/rapggu.v128.7932.
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Over the past decade GGU has colIected basic glaciological, climatic and hydrological data from the basins that are potential suppliers of hydropower in West Greenland. Detailed topographic maps of the margins of the lnland Ice near Frederikshåb and Jakobshavn have been used to record changes in the drainage pattern due to changing positions of the ice margin. Landsat images are used to augment the field data, particularly using scenes recorded late in the melting season under low sun angles. Computer processing of the Landsat data enhances individual elements that are otherwise not clearly discernable. Since ice-dammed lakes can form natural reservoirs they have been closely studied with a view to controlling the periodic catastrophic outbursts. Statisticai modeIling has been used extensively utilising long series of meteorological data from coastaIstations to simulate the mass balance and mnoff patterns on the margin of the lnland lce.
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Singh, Gagandeep, Vishwa Bandhu Singh Chandel, and Simrit Kahlon. "Flood Hazard Modelling in Upper Mandakini Basin of Uttarakhand." Current World Environment 16, no. 3 (December 31, 2021): 880–89. http://dx.doi.org/10.12944/cwe.16.3.18.
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Floods in Himalayan region raise serious concerns regarding ongoing path of development as recent manifestations of catastrophic events establish link between climate changes and risk to anthropogenic activities in mountainous regions. Scientists predict frequent occurrence of such disasters wherein rapid glacial melting; incidents of glacial lake outburst and weather extremes may trigger floods in the Himalayan mountains. This paper examined flood risk in Upper Mandakini basin through GIS based flood simulationto highlight flood potential and risk associated with such hazard in the study area.It is observed that floods in study area display hazardous interplay of natural terrain gradient, high kinetic energy of streams, and intense rainfall. The upper sections of basin that includes Kali Ganga, Mandani Ganga, Madhyamaheshwar and Mandakini rivers shows high flood susceptibility with greatest risk in the latter. Such hazardousness is likely to be intensified by ongoing anthropogenic activities in the basin.
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Myasnikova L.P., Drobotko V.F., Borzenko A.P., Boiko Yu. M., Marikhin V.A., Terekhov S.A., and Yagovkina M.A. "Search for optimal conditions for monolithization of ultra-high-molecular-weight polyethylene reactor powder." Physics of the Solid State 63, no. 13 (2022): 1802. http://dx.doi.org/10.21883/pss.2022.13.52325.164.
Full textAbstract:
In order to clarify the possibility of sintering reactor powders of ultra-high molecular weight polyethylene under pressure at a temperature higher than its equilibrium melting point at atmospheric pressure (T0m) without catastrophic changes in the internal structure of particles, a comparative WAXS analysis was carried out of the samples sintered below (T<T0m) and above (T>T0m) this temperature and cooled under different conditions. A structural analysis of the X-ray scattering curves recorded in the Bragg-Brentano mode on a 2D Phaser Bruker diffractometer from UHMWPE reactor powders sintered under different conditions was carried out, and the crystallite sizes were calculated. It was found that an increase in the sintering temperature above T0m does not significantly change the crystal structure of the polymer, and the precursors produced can be used for further orientational hardening. Keywords: ultrahigh molecular weight polyethylene reactor powders, sintering, WAXS.
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David, S. A., T. DebRoy, and J. M. Vitek. "Phenomenological Modeling of Fusion Welding Processes." MRS Bulletin 19, no. 1 (January 1994): 29–35. http://dx.doi.org/10.1557/s0883769400038835.
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Welding is utilized in 50% of the industrial, commercial, and consumer products that make up the U.S. gross national product. In the construction of buildings, bridges, ships, and submarines, and in the aerospace, automotive, and electronic industries, welding is an essential activity. In the last few decades, welding has evolved from an empirical art to a more scientifically based activity requiring synthesis of knowledge from various disciplines. Defects in welds, or poor performance of welds, can lead to catastrophic failures with costly consequences, including loss of property and life.Figure 1 is a schematic diagram of the welding process showing the interaction between the heat source and the base metal. During the interaction of the heat source with the material, several critical events occur: melting, vaporization, solidification, and solid-state transformations. The weldment is divided into three distinct regions: the fusion zone (FZ), which undergoes melting and solidification; the heat-affected zone (HAZ) adjacent to the FZ, that may experience solid-state phase changes but no melting; and the unaffected base metal (BM).Creating the extensive experimental data base required to adequately characterize the highly complex fusion welding process is expensive and time consuming, if not impractical. One recourse is to simulate welding processes either mathematically or physically in order to develop a phenomenological understanding of the process. In mathematical modeling, a set of algebraic or differential equations are solved to obtain detailed insight of the process. In physical modeling, understanding of a component of the welding process is achieved through experiments designed to avoid complexities that are unrelated to the component investigated.In recent years, process modeling has grown to be a powerful tool for understanding the welding process. Using computational modeling, significant progress has been made in evaluating how the physical processes in the weld pool influence the development of the weld pool and the macrostructures and microstructures of the weld.
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Luna Ramírez, A., J. Porcayo-Calderon, Z. Mazur, V. M. Salinas-Bravo, and L. Martinez-Gomez. "Microstructural Changes during High Temperature Service of a Cobalt-Based Superalloy First Stage Nozzle." Advances in Materials Science and Engineering 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/1745839.
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Superalloys are a group of alloys based on nickel, iron, or cobalt, which are used to operate at high temperatures (T> 540°C) and in situations involving very high stresses like in gas turbines, particularly in the manufacture of blades, nozzles, combustors, and discs. Besides keeping its high resistance to temperatures which may approach 85% of their melting temperature, these materials have excellent corrosion resistance and oxidation. However, after long service, these components undergo mechanical and microstructural degradation; the latter is considered a major cause for replacement of the main components of gas turbines. After certain operating time, these components are very expensive to replace, so the microstructural analysis is an important tool to determine the mode of microstructure degradation, residual lifetime estimation, and operating temperature and most important to determine the method of rehabilitation for extending its life. Microstructural analysis can avoid catastrophic failures and optimize the operating mode of the turbine. A case study is presented in this paper.
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Boerner, D. E., B. Milkereit, and A. Davidson. "Geoscience impact: a synthesis of studies of the Sudbury Structure." Canadian Journal of Earth Sciences 37, no. 2-3 (April 2, 2000): 477–501. http://dx.doi.org/10.1139/e99-062.
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Geophysical probing results are synthesized into a three-dimensional framework necessary for understanding the genesis of the Sudbury Structure, based primarily on seismic reflection results centred on the Sudbury Igneous Complex. Remnants of crustal melting from a catastrophic meteorite impact are superimposed on the juxtaposition of mid-crustal rocks exhumed during the Archean against deformed Paleoproterozoic sedimentary rocks. Sedimentation, metamorphism, deformation, and metasomatic overprints are all part of the post-impact history of Sudbury and tend to dominate the geophysical response of the structure. Pre-impact deformation, although certainly preserved in some aspects of Sudbury geology, is not clearly expressed in the geophysical data, nor are any elements of impact-induced deformation. Geophysical views of the Sudbury Igneous Complex are thus somewhat biased in representing mostly the post-impact, but pre-Grenvillian history of the region, with the exception of igneous events. Establishing the proper context for integrating these geophysical results in the genetic interpretation of the Sudbury Structure depends crucially upon timing constraints.
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Hettal, Sarah, Sébastien Roland, and Xavier Colin. "Consequences of Radiothermal Ageing on the Crystalline Morphology of Additive-Free Silane-Crosslinked Polyethylene." Polymers 14, no. 14 (July 18, 2022): 2912. http://dx.doi.org/10.3390/polym14142912.
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The radiothermal ageing of silane-crosslinked low-density PE (Si-XLPE) films was studied in the air under three different γ dose rates (8.5, 77.8, and 400 Gy·h−1) at a low temperature close to ambient (47, 47, and 21 °C, respectively). Changes in crystalline morphology were investigated using a multi-technique approach based on differential scanning calorimetry (DSC), wide- (WAXS) and small-angle X-ray scattering (SAXS), and density measurements. In particular, the changes in four structural variables were accurately monitored during radiothermal ageing: crystallinity ratio (XC), crystalline lamellae thickness (LC), long period (Lp), and interlamellar spacing (La). Concerning the changes in XC, a perfect agreement was found between DSC and WAXS experiments. Successive sequences of self-nucleation and annealing (SSA) were also performed on aged Si-XLPE samples in the DSC chamber in order to assess the thickness distribution of crystalline lamellae. This method allowed the thermally splitting of the melting domain of Si-XLPE into a series of elementary melting peaks, with each one characterised by a distinct thickness of crystalline lamellae. DSC (used with the SSA method) showed a slight increase in LC during the oxidation of Si-XLPE, while SAXS confirmed a catastrophic decrease in La. The critical value of the interlamellar spacing characterising the ductile/brittle transition of Si-XLPE was found to be of the same order of magnitude as that for linear polyethylene (LaF≈6 nm). This structural end-of-life criterion can now be used for predicting the lifetime of Si-XLPE in a nuclear environment.
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Burk, Steffen, and Hans Jürgen Christ. "High-Temperature Oxidation Performance of Mo-Si-B Alloys: Current Results, Developments and Opportunities." Advanced Materials Research 278 (July 2011): 587–92. http://dx.doi.org/10.4028/www.scientific.net/amr.278.587.
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Ni-base superalloys are approaching the melting point as their fundamental limitation. For high-temperature components one possibility aiming at a further increase of efficiency, e.g. of jet turbines, is the use of refractory metals. Mo as base material is suitable for operating temperatures far beyond 1200°C. As a consequence of the formation of volatile Mo-oxides, it exhibits no intrinsic oxidation resistance when exceeding 700°C. Mo-Si-B alloys have melting points around 2000°C and retain good mechanical properties and oxidation resistance at very high temperatures. In air, the three-phase Mo-Si-B alloy dealt with in this paper shows excellent oxidation behaviour between 900°C-1300°C as a consequence of the formation of a protective silica scale. Below 900°C, alloys of this class suffer from catastrophic oxidation, leading to an evaporation of Mo-oxide and giving rise to a linear rate law of the weight loss. A protective oxide layer is not formed as a consequence of simultaneous and competitive Mo- and Si-oxide formation. Several approaches are possible to improve the oxidation performance of Mo-Si-B alloys, especially in this moderate temperature range. These include classical alloying, e.g. with Cr aiming for protective Cr-oxide scales, addition of small amounts of reactive elements for microstructure-refinement as well as selective oxidation of silica in oxygen-deficient atmospheres prior to operation in air. The results presented show promising opportunities and indicate that an oxidation protection from room temperature up to 1300°C requires a combination of the suggested approaches.
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Souza, José Vitor C., Maria do Carmo de Andrade Nono, Sergio Luiz Mineiro, M. V. Ribeiro, and Olivério Moreira Macedo Silva. "Evaluation of the Performance of α-SiAlON Tool when Turning Ti–6Al–4V Alloy without Coolant." Materials Science Forum 591-593 (August 2008): 554–59. http://dx.doi.org/10.4028/www.scientific.net/msf.591-593.554.
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Due to their high hardness and wear resistance, Si3N4 based ceramics are one of the most suitable cutting tool materials for machining cast iron, nickel alloys and hardened steels. However, their high degree of brittleness usually leads to inconsistent results and sudden catastrophic failures. This necessitates a process optimization when machining superalloys with Si3N4 based ceramic cutting tools. The tools are expected to withstand the heat and pressure developed when machining at higher cutting conditions because of their high hardness and melting point. This paper evaluates the performance of α-SiAlON tool in turning Ti–6Al–4V alloy at high cutting conditions, up to 250 m min−1, without coolant. Tool wear, failure modes and temperature were monitored to access the performance of the cutting tool. Test results showed that the performance of α-SiAlON tool, in terms of tool life, at the cutting conditions investigated is relatively poor due probably to rapid notching and excessive chipping of the cutting edge. These facts are associated with adhesion and diffusion wear rate that tends to weaken the bond strength of the cutting tool.
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Ramos da Silva, Renato, Gil Bohrer, David Werth, Martin J. Otte, and Roni Avissar. "Sensitivity of Ice Storms in the Southeastern United States to Atlantic SST—Insights from a Case Study of the December 2002 Storm." Monthly Weather Review 134, no. 5 (May 1, 2006): 1454–64. http://dx.doi.org/10.1175/mwr3127.1.
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Abstract Meteorological observations and model simulations are used to show that the catastrophic ice storm of 4–5 December 2002 in the southeastern United States resulted from the combination of a classic winter storm and a warm sea surface temperature (SST) anomaly in the western Atlantic Ocean. At the time of the storm, observations show that the Atlantic SST near the southeastern U.S. coast was 1.0°–1.5°C warmer than its multiyear mean. The impact of this anomalous SST on the ice accumulation of the ice storm was evaluated with the Regional Atmospheric Modeling System. The model shows that a warmer ocean leads to the conversion of more snow into freezing rain while not significantly affecting the inland surface temperature. Conversely, a cooler ocean produces mostly snowfall and less freezing rain. A similar trend is obtained by statistically comparing observations of ice storms in the last decade with weekly mean Atlantic SSTs. The SST during an ice storm is significantly and positively correlated with a deeper and warmer melting layer.
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Moores, Howard D. "On the Formation of the Tunnel Valleys of the Superior Lobe, Central Minnesota." Quaternary Research 32, no. 1 (July 1989): 24–35. http://dx.doi.org/10.1016/0033-5894(89)90029-x.
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AbstractWhen considering the formation of tunnel valleys, most researchers have appealed to basal melting as the primary source of water. Erosion of the tunnel valleys can then be accomplished by steady-state drainage over a long period or by storage and subsequent catastrophic release. However, field relationships in a large system of tunnel valleys formed by the Superior lobe in central Minnesota indicate that another source of water must be considered. The Minnesota tunnel valleys are composed of individual segments 10–20 km long, and the segments commonly terminate in subaerial outwash fans at recessional ice margin positions. Eskers, associated with the tunnel valleys, are also composed of short segments, frequently beginning at moulin kames and terminating at the head of outwash fans. The dominant source of the water responsible for tunnel-valley formation was seasonal meltwater from the glacier surface that reached the bed through moulins and crevasses. The apparent continuity of the valleys resulted from the headward development of the englacial drainage system during ice retreat.
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Matthews, J. Brian, and J. B. Robin Matthews. "In situ measurement shows ocean boundary layer physical processes control catastrophic global warming." JOURNAL OF ADVANCES IN PHYSICS 5, no. 1 (August 2, 2014): 681–704. http://dx.doi.org/10.24297/jap.v5i1.1975.
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The infrared greenhouse gas heat trap at the top of the atmosphere controls anthropogenic global warming (AGW) heat balance. Processes at the top of the ocean similarly control the 93% of AGW in the oceans. The tropics are a global year-round ocean heat source. Heat is transported in the ocean by sinking brine from tropical evaporation and polar freezing. Buoyant freshwater and ice barriers limit heat loss from the surface layer. The almost completely unstudied ocean surface skin is critically important to understanding global warming and climate change processes. Studies to date have concentrated on atmospheric warming mainly from land-air data. In this paper we present the first hourly meridional 3m and surface observations in the equatorial Pacific from Tahiti to Hawaii for direct measurement of evaporation and ocean boundary layer heat trapping. We relate this to poleward heat and freshwater transport and ocean warming moderation by basal icemelt of floating ice explored in a second paper [1].We show heat sequestration below 3m in the hypersaline (>35.5‰) southern hemisphere (SH) is limited to ~6MJm-2day-1 but evaporation is 7.3mmm-2day--1, at salinity ~36.4‰ and temperature >28ºC. In the northern hemisphere (NH) tropics the corresponding figures are ~12 MJm-2day-1 and ~4.5mmm-2day--1. Equatorial upwelling and the 50m deep Bering Strait limit buoyant surface outflow from the North Pacific.We found pairs of counter-rotating vertical meridional tropical cells (MTCs), ~300-1200km wide, ~100m deep form separate SH and NH systems with little cross-equatorial flux. Counter-rotating Lagrangian wind-driven gyres transport heat and freshwater polewards in seasonally and tidally moderated stratified surface waters. The zonal geostrophic balance is maintained by the Equatorial Undercurrent (EUC) with an eastbound core ~140cms-1 and density ~25.0 at 50-150m.Global warming and polar icemelt has been underestimated from wrong assumptions of the processes in the top 3m of oceans. These are the unverified beliefs that ocean evaporation depends on windspeed and relative humidity that the ocean is well mixed to 10m depths, and by neglect of water density determined by both salinity and temperature. Temperature measurement to ±0.01ºC is required to account for the 3000x greater volumetric heat capacity of seawater to air (3.9x106: 1.3x103Jm-3°C-1). Most SST data are to atmospheric standards (>±0.5°C). Evaporation depends only on temperature (Clausius-Clapeyron). Heat sequestration depends on the buoyant surface layer processes and underlying density gradient. Eleven interconnected counter-rotating Lagrangian wind-driven surface gyres form a global circulation system that carries buoyant surface water masses at speeds much higher than Eulerian geostrophic currents. Polar ice may erode year-round from basal melting from warm subsurface water.This explains contrasting Arctic/Antarctic warming impacts. We suggest many more in situ 3m timeseries especially meridional ones are needed to confirm our findings. In a second paper on centennial daily surface timeseries we show ocean surface warming trend rate post about 1976-1986 is ~0.037ºCyr-1, i.e. >1ºC in 20 years [1]. We suggest global warming research be concentrated on the top of the ocean through multidisciplinary timeseries fieldwork verification, monitoring and modeling. This would best be conducted through a cost-efficient dynamic adaptive scientific management for rapid determination of mitigation and adaptation strategies. Reducing troposphere greenhouse gases can only reduce warming. Mitigation maybe possible through heat energy extraction from geothermal, ocean, tidal and solar sources.
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Johnson, Robert Glenn. "Hudson Strait ice dam collapse: An explanation for the onset of the Younger Dryas cold climate in Europe in only one year." JOURNAL OF ADVANCES IN NATURAL SCIENCES 18 (February 28, 2021): 1–11. http://dx.doi.org/10.24297/jns.v18i.8961.
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The Younger Dryas cold climate event in Europe began abruptly at about 12,679 years BP. The abruptness of the onset was caused by the rapid collapse of a dynamic ice dam that had existed because of ice stream flow across the east end of Hudson Strait in northern Canada. The resulting flood of icebergs into the southern half of the Northern Gyre adjacent to the Gulf Stream converted western Europe’s mild climate to an arctic climate. The collapse event was caused by the last large accumulation of glacial ice in the thick ice dome of Hudson Bay. The accumulation created a pressure gradient that forced an ice stream flow eastward in Hudson Strait. A highly saline sub-glacial lake had formed earlier in the western part of the strait. The ice stream flow entrained saline lake water in a network of channels at the seabed between the lake and the ice dam, melting and extending the network eventually to and beneath the ice dam. This detached much of the ice dam from its frozen bed and caused its catastrophic collapse and the onset of the Younger Dryas in only one year.
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Schulte, L., J. C. Peña, F. Carvalho, T. Schmidt, R. Julià, J. Llorca, and H. Veit. "A 2600-year history of floods in the Bernese Alps, Switzerland: frequencies, mechanisms and climate forcing." Hydrology and Earth System Sciences 19, no. 7 (July 10, 2015): 3047–72. http://dx.doi.org/10.5194/hess-19-3047-2015.
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Abstract. A 2600-year long composite palaeoflood record is reconstructed from high-resolution delta plain sediments of the Hasli–Aare floodplain on the northern slope of the Swiss Alps. Natural proxies compiled from sedimentary, geochemical and geomorphological data were calibrated by textual and factual sources and instrumental data. No fewer than 12 of the 14 historically recorded extreme events between 1480 and the termination of the Hasli–Aare river channel correction in 1875 were also identified by coarse-grained flood layers, log(Zr / Ti) peaks and factor 1 anomalies. Geomorphological, historical and instrumental data provide evidence for flood damage intensities and discharge estimations of severe and catastrophic historical floods. Spectral analysis of the geochemical and documentary flood series and several climate proxies (TSI, δ18O, tree-rings, NAO, SNAO) identify similar periodicities of around 60, 80, 100, 120 and 200 years during the last millennia, indicating the influence of the North Atlantic circulation and solar forcing on alpine flood dynamics. The composite floodplain record illustrates that periods of organic soil formation and deposition of phyllosilicates (from the medium high catchment area) match those of total solar irradiance maxima, suggesting reduced flood activity during warmer climate pulses. Aggradation with multiple sets of flood layers with increased contribution of siliciclasts from the highest catchment area (plutonic bedrock) (e.g. 1300–1350, 1420–1480, 1550–1620, 1650–1720 and 1811–1851 cal yr AD) occurred predominantly during periods with reduced solar irradiance, lower δ18O anomalies, cooler summer temperatures and phases of drier spring climate in the Alps. Increased water storage by glaciers, snow cover and snow patches susceptible to melting processes associated with rainfall episodes and abrupt rises in temperature substantially increased surface runoff on slopes and discharges of alpine rivers. This interpretation is in agreement with the findings that the severe and catastrophic historical floods in the Aare since 1670 occurred mostly during positive SNAO (Summer North Atlantic Oscillation) pulses after years or even decades dominated by negative SNAO and cooler annual temperatures.
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Schulte, L., J. C. Peña, F. Carvalho, T. Schmidt, R. Julià, J. Llorca, and H. Veit. "A 2600 year history of floods in the Bernese Alps, Switzerland: frequencies, mechanisms and climate forcing." Hydrology and Earth System Sciences Discussions 12, no. 3 (March 27, 2015): 3391–448. http://dx.doi.org/10.5194/hessd-12-3391-2015.
Full textAbstract:
Abstract. A 2600 yr long composite palaeoflood record is reconstructed from high-resolution delta plain sediments of the Hasli–Aare floodplain on the northern slope of the Swiss Alps. Natural proxies compiled from sedimentary, geochemical and geomorphological data were calibrated by textual and factual sources and instrumental data. No fewer than 12 of the 14 historically recorded extreme events between 1480 and the termination of the Hasli–Aare Correction in 1875 were also identified by coarse-grained flood layers, log(Zr/Ti) peaks and Factor 1 anomalies. Geomorphological, historical and instrumental data provide evidence for flood damage intensities and discharge estimations of severe and catastrophic historical floods. Spectral analysis of the geochemical and documentary flood series and several climate proxies (TSI, δ18O, tree-rings, NAO, SNAO) identify similar periodicities of around 60, 80, 100, 120 and 200 years during the last millennia, indicating the influence of the North Atlantic circulation and solar forcing on alpine flood dynamics. The composite floodplain record illustrates that periods of organic soil formation and deposition of phyllosilicates (from the medium high catchment area) match those of Total Solar Irradiance maxima, suggesting reduced flood activity during warmer climate pulses. Aggradation of clusters of flood layers with increased contribution of siliciclasts from the highest catchment area (plutonic bedrock) (e.g., 1300–1350, 1420–1480, 1550–1620, 1650–1720 and 1811–1851 cal yr AD) occurred predominantly during periods with reduced solar irradiance, lower δ18O anomalies, cooler summer temperatures and phases of drier spring climate in the Alps. Increased water storage by glaciers, snow cover and snow patches susceptible to melting processes associated with rainfall episodes and abrupt rises in temperature substantially increased surface run-off on slopes and discharges of alpine rivers. This interpretation is in agreement with the findings that the severe and catastrophic historical floods in the Aare since 1670 occurred mostly during positive SNAO pulses after years or even decades dominated by negative SNAO and cooler annual temperatures.
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Prisyajnyuk, V., S. Semychayevsky, M. Yakimenko, and M. Osadchuk. "REGARDING THE USE OF MODERN TECHNICAL MEANS OF PROTECTION AGAINST FLOOD OF TERRITORIES AND FACILITIES FOR DIFFERENT PURPOSES." Municipal economy of cities 1, no. 161 (March 26, 2021): 315–19. http://dx.doi.org/10.33042/2522-1809-2021-1-161-315-319.
Full textAbstract:
The danger to society caused by the consequences of natural disasters tends to increase despite the general technical progress and the application of measures to prevent them and combat them. Every year the number of victims, in particular, from floods increases by an average of 6%. Flooding in certain areas can occur due to floods and inundations. Floods are natural processes that occur in the biosphere and affect the planet for millennia. Flood is a significant flooding of the area due to rising water levels in rivers, lakes, reservoirs, caused by downpours, spring snowmelt, wind surges, destruction of dams, dams and more. Floods cause great material damage and casualties. The water level in reservoirs depends on many different factors. All over the world, experts conduct long-term observations, tracking all seasonal changes, and collect data for forecasting. Floods and their causes are well studied. The main causes of these disasters are: - prolonged rains; - melting snow; - raising the bottom; - strong winds and storms; - groundwater; Thus, the issue of using modern technical means of protection against flooding of territories and objects of various purposes is relevant. A number of publications consider current trends in effective flood risk management planning in the European Union and describe the catastrophic consequences of floods and ways to combat them, and so on. At the same time, these studies do not contain data on testing and implementation in Ukraine of modern technical means to combat floods in the EU. To address these issues, the Institute of Public Administration and Research on Civil Defense commissioned by the State Service of Ukraine for Emergencies has developed a method of testing water-absorbing devices designed for: - flood protection; - changes in the direction of water flow during floods, torrential rains, melting snow, etc. - removal of water from flooded areas (basements, garages, etc.); - elimination of environmental accidents (spills of oil, diesel fuel and other chemicals). Developed by the Institute of Public Administration and Research on Civil Protection, the method of testing water-absorbing means will allow in the future to test and assess the suitability of such technical means for use by fire and rescue units when performing tasks to remove water from flooded areas and create barriers to water. time of protection against floods, changes in the direction of water flow during floods, torrential rains, melting snow, etc.
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Gupta, Parnika. "Role of Media and Indigenous Communities to Combat Climate Change." International Journal of Science and Engineering Applications 11, no. 05 (May 2022): 55–60. http://dx.doi.org/10.7753/ijsea1105.1001.
Full textAbstract:
Since the industrial revolution, the greenhouse gas emissions have been on the constant rise and the global average temperature has increased by 1.1 degree Celsius as compared to pre-industrial era. This alarming climate change situation caused by human activities has already been causing devastating effects everywhere on the planet. The melting of sea ice, thawing of the permafrost, increase in natural hazards and their frequencies, reduction in the biodiversity of ecological areas, increase in sea levels, deterioration of species & wild populations, etc. are all pointing towards a direct threat to human well-being posed by the climate change. This research paper, whose idea germinated in the mind of the author while attending Arctic Circle Assembly 2021 in Reykjavik Iceland, circles around the role and position of media and indigenous communities in climate change mitigation and adaption by exploring key questions like challenges and narratives of climate coverage by media, a requirement for revolutionizing the institution of media, the importance of indigenous peoples and traditional knowledge for combatting climate change to name a few. The paper argues various elements affecting media and indigenous communities and concludes the crucial involvement for media and indigenous peoples to act for saving the planet considering the huge scale of this catastrophic climate change scenario.
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McKamey, C. G., P. F. Tortorelli, J. H. DeVan, and C. A. Carmichael. "A study of pest oxidation in polycrystalline MoSi2." Journal of Materials Research 7, no. 10 (October 1992): 2747–55. http://dx.doi.org/10.1557/jmr.1992.2747.
Full textAbstract:
MoSi2 is a promising high-temperature material with low density (6.3 g/cm3), high melting point (2020 °C), and good oxidation resistance at temperatures to about 1900 °C. However, in the intermediate temperature range between 400 and 600 °C, it is susceptible to a “pest” reaction which causes catastrophic disintegration by a combination of oxidation and fracture. In this study, we have used polycrystalline MoSi2, produced by arc-casting of the pure elements and by cold and hot pressing of alloy powders, to characterize the pest reaction and to determine the roles of composition, grain or phase boundaries, and physical defects on the oxidation and fracture of specimens exposed to air at 500 °C. It was found that pest disintegration occurs through transport of oxygen into the interior of the specimen along pre-existing cracks and/or pores, where it reacts to form MoO3 and SiO2. The internal stress produced during the formation of MoO3 results in disintegration to powder. Near the stoichiometric ratio, the susceptibility to pest disintegration increases with increasing molybdenum content and with decreasing density. Silicon-rich alloys were able to form protective SiO2 and showed no indication of disintegration, even at densities as low as 60%.
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Judd, Alan, David Long, and Michael Sankey. "Pockmark formation and activity, U.K. block 15/25, North Sea." Bulletin of the Geological Society of Denmark 41 (March 30, 1994): 34–49. http://dx.doi.org/10.37570/bgsd-1995-41-04.
Full textAbstract:
Digital seismic reflection (boomer) profiles of an active pockmark, in UK block 15/25, North Sea, reveal that the feature was formed prior to the deposition of the most recent sediments, probably by vigorous (or even catastrophic) gas escape. This release may have been triggered by the melting of ground ice when North Atlantic waters first entered the North Sea after the last glaciation, about 13,000 years ago. Possible sources of the gas are investigated by examining the composite log from a nearby petroleum exploration well; it is concluded that, although the gas may .originate from the Kimmeridge Clay, it probably comes from lignites of Tertiary age. Its migration towards the seabed is interrupted by local accumulations at several horizons, the shallowest of which (<80 m below seabed) is trapped beneath clayey sediments of the Coal Pit Formation. The topography of the base of this layer apparently controls the location of gas migration pathways to the seabed. As these lead to pockmarks which formed long ago, and as these pockmarks are still active today, it is probable that the migration pathways have remained throughout the intervening period. Gas accumulating beneath the Coal Pit Formation may migrate laterally to reach the pathways.
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Modest, M. F. "Transient Elastic and Viscoelastic Thermal Stresses During Laser Drilling of Ceramics." Journal of Heat Transfer 120, no. 4 (November 1, 1998): 892–98. http://dx.doi.org/10.1115/1.2825908.
Full textAbstract:
Lasers appear to be particularly well suited to drill and shape hard and brittle ceramics, which are almost impossible to netshape to tight tolerances, and are presently machined in industry only by diamond grinding. Unfortunately, the large, focussed heat fluxes that allow the ready melting and ablation of material, also result in large localized thermal stresses within the narrow heat-affected zone, which can lead to microcracks, significant decrease in bending strength, and even catastrophic failure. In order to assess the where, when, and what stresses occur during laser drilling, that are responsible for cracks and decrease in strength, elastic and viscoelastic stress models have been incorporated into our two-dimensional drilling code. The code is able to predict temporal temperature fields as well as the receding solid surface during CW or pulsed laser drilling. Using the resulting drill geometry and temperature fields as well as the receding solid surface during CW of pulsed laser drilling. Using the resulting drill geometry and temperature field, elastic stresses as well as viscoelastic stresses are calculated as they develop and decay during the drilling process. The viscosity of the ceramic is treated as temperature-dependent, limiting viscoelastic effects to a thin layer near the ablation front where the ceramic has softened.
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Deeming, K. R., B. McGuire, and P. Harrop. "Climate forcing of volcano lateral collapse: evidence from Mount Etna, Sicily." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 368, no. 1919 (May 28, 2010): 2559–77. http://dx.doi.org/10.1098/rsta.2010.0054.
Full textAbstract:
In this study, we present evidence for early Holocene climatic conditions providing circumstances favourable to major lateral collapse at Mount Etna, Sicily. The volcano’s most notable topographic feature is the Valle del Bove, a 5×8 km cliff-bounded amphitheatre excavated from the eastern flank of the volcano. Its origin due to prehistoric lateral collapse is corroborated by stürtzstrom deposits adjacent to the amphitheatre’s downslope outlet, but the age, nature and cause of amphitheatre excavation remain matters for debate. Cosmogenic 3 He exposure ages determined for eroded surfaces within an abandoned watershed flanking the Valle del Bove support channel abandonment ca 7.5 ka BP, as a consequence of its excavation in a catastrophic collapse event. Watershed development was largely dictated by pluvial conditions during the early Holocene, which are also implicated in slope failure. A viable trigger is magma emplacement into rift zones in the eastern flank of a water-saturated edifice, leading to the development of excess pore pressures, consequent reduction in sliding resistance, detachment and collapse. Such a mechanism is presented as one potential driver of future lateral collapse in volcanic landscapes forecast to experience increased precipitation or melting of ice cover as a consequence of anthropogenic warming.
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Rototaeva, O. V., G. A. Nosenko, A. M. Kerimov, S. S. Kutuzov, I. I. Lavrentiev, S. A. Nikitin, A. A. Kerimov, and L. N. Tarasova. "Changes of the mass balance of the Garabashy Glacier, Mount Elbrus, at the turn of 20th and 21st centuries." Ice and Snow 59, no. 1 (March 20, 2019): 5–22. http://dx.doi.org/10.15356/2076-6734-2019-1-5-22.
Full textAbstract:
Long-term series of observations on the glacier of the southern slope of Elbrus manifest the change of two climatic periods in the highlands of the Caucasus. During the first one, relatively cold and snowy period of 1982–1997 with a small positive mass balance, the Garabashi Glacier accumulated a layer of 0.8 m.e. The second period (1998–2017) is characterized by rising summer air temperatures and increasing precipitation in the first decade, and catastrophic melting in 2010–2017. The mass balance of the glacier averaged −0.63 m w.e. yr−1, and in some years it reached −1.00 ÷ −1.50 m w.e. yr−1. In the last ten years, frequency of vast anticyclones covering the southern part of the European part of Russia and the North Caucasus increased. Summer temperatures in the Elbrus region rose to almost the level of the 1950s that was the hottest decade of the XX century. Duration of the summer season on the glaciers increased. Active melting resulted in elevation of the equilibrium line of the Garabashy Glacier by 200 m. In the main part of the glacier alimentation area, i.e. at heights of 3800–4000 m, the large parts of the firn area had disappeared, but open ice of the ablation zone had appeared. The former areas of the "warm" firn zone, where up to 35% of melt water retained within the 20‑meter firn thickness, were replaced by the firn-ice zone, and the ice discharge increased. The glacier alimentation is decreased, and its tongue retreats with increasing velocity. Rocks and entire lava ridges release from ice at different levels of the glacier. The inter-annual variations of the glacier mass balance are controlled by intensity of ablation. In the second period, the correlation coefficient of these values reached 0.97 compared to 0.82 in the first one. In total over 36 years of observations, reduction of the glacier mass during the second period resulted in loss of volume (0.05 km3 or 14%), area (0.51 km2 or 11.4%), and of ice layer (11.4 m).