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1.
A number of examples are presented to substantiate that submarine landslides have occurred along most continental margins and along several volcano flanks. Their properties of importance for tsunami generation (i.e. physical dimensions, acceleration, maximum velocity, mass discharge, and travel distance) can all gain extreme values compared to their subaerial counterparts. Hence, landslide tsunamis may also be extreme and have regional impact. Landslide tsunami characteristics are discussed explaining how they may exceed tsunamis induced by megathrust earthquakes, hence representing a significant risk even though they occur more infrequently. In fact, submarine landslides may cause potentially extreme tsunami run-up heights, which may have consequences for the design of critical infrastructure often based on unjustifiably long return periods. Giant submarine landslides are rare and related to climate changes or glacial cycles, indicating that giant submarine landslide tsunami hazard is in most regions negligible compared to earthquake tsunami hazard. Large-scale debris flows surrounding active volcanoes or submarine landslides in river deltas may be more frequent. Giant volcano flank collapses at the Canary and Hawaii Islands developed in the early stages of the history of the volcanoes, and the tsunamigenic potential of these collapses is disputed. Estimations of recurrence intervals, hazard, and uncertainties with today’s methods are discussed. It is concluded that insufficient sampling and changing conditions for landslide release are major obstacles in transporting a Probabilistic Tsunami Hazard Assessment (PTHA) approach from earthquake to landslide tsunamis and that the more robust Scenario-Based Tsunami Hazard Assessment (SBTHA) approach will still be most efficient to use. Finally, the needs for data acquisition and analyses, laboratory experiments, and more sophisticated numerical modelling for improved understanding and hazard assessment of landslide tsunamis are elaborated. 相似文献
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Gillian Rose 《Geoforum》2009,40(1):46-54
The paper begins with the recent interest in what Mbembe has called ‘necropolitics’: the politics of the distribution of life and death by modern sovereign states. The necropolitical works through the production of spatialities, visualities, and bodies that are classed, racialised and gendered in particular ways. The paper explores a series of such productions in its discussion of the British press coverage of the bombs that exploded on London’s public transport system on 7 July 2005, and in particular the photographs used by the newspapers. It argues that the newspapers pictured bodies as gendered and racialised, with the former fixed and visible much more clearly than the latter. It further argues that the newspapers differentiated between various bodies by assuming that a certain sort of care was deserved only by some of those involved in the bombings. Finally, the paper examines how the coverage worked to place the readers of the newspapers in a specific position in the necropolitical order of power as citizens who care only for certain people, and in a particular way. The paper concludes by considering the implications of that specific caring for contemporary necropolitics and its visualities and spatialities. 相似文献
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Hydrogeology Journal - There is a pressing need to improve public administration of groundwater abstraction and use, given the global need to achieve sustainable resource exploitation and to reduce... 相似文献
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Much of the coal consumed in the US since the end of the last century has been produced from the Pennsylvanian strata of the Appalachian basin. Even though quantities mined in the past are less than they are today, this basin yielded from 70% to 80% of the nation's annual coal production from the end of the last century until the early 1970s. During the last 25 years, the proportion of the nation's coal that was produced annually from the Appalachian basin has declined markedly, and today it is only about 40% of the total. The amount of coal produced annually in the Appalachian basin, however, has been rising slowly over the last several decades, and has ranged generally from 400 to 500 million tons (Mt) per year.A large proportion of Appalachian historical production has come from relatively few counties in southwestern Pennsylvania, northern and southern West Virginia, eastern Kentucky, Virginia and Alabama. Many of these counties are decades past their years of peak production and several are almost depleted of economic deposits of coal. Because the current major consumer of Appalachian coal is the electric power industry, coal quality, especially sulfur content, has a great impact on its marketability. High-sulfur coal deposits in western Pennsylvania and Ohio are in low demand when compared with the lower sulfur coals of Virginia and southern West Virginia. Only five counties in the basin that have produced 500 Mt or more exhibit increasing rates of production at relatively high levels. Of these, six are in the central part of the basin and only one, Greene County, Pennsylvania, is in the northern part of the basin. Decline rate models, based on production decline rates and the decline rate of the estimated, “potential” reserve, indicate that Appalachian basin annual coal production will be 200 Mt or less by the middle of the next century. 相似文献
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Applied flood risk analyses, especially in urban areas, very often pose the question how detailed the analysis needs to be
in order to give a realistic figure of the expected risk. The methods used in research and practical applications range from
very basic approaches with numerous simplifying assumptions up to very sophisticated, data and calculation time demanding
applications both on the hazard and on the vulnerability part of the risk. In order to shed some light on the question of
required model complexity in flood risk analyses and outputs sufficiently fulfilling the task at hand, a number of combinations
of models of different complexity both on the hazard and on the vulnerability side were tested in a case study. The different
models can be organized in a model matrix of different complexity levels: On the hazard side, the approaches/models selected
were (A) linear interpolation of gauge water levels and intersection with a digital elevation model (DEM), (B) a mixed 1D/2D
hydraulic model with simplifying assumptions (LISFLOOD-FP) and (C) a Saint-Venant 2D zero-inertia hyperbolic hydraulic model
considering the built environment and infrastructure. On the vulnerability side, the models used for the estimation of direct
damage to residential buildings are in order of increasing complexity: (I) meso-scale stage-damage functions applied to CORINE
land cover data, (II) the rule-based meso-scale model FLEMOps+ using census data on the municipal building stock and CORINE
land cover data and (III) a rule-based micro-scale model applied to a detailed building inventory. Besides the inundation
depths, the latter two models consider different building types and qualities as well as the level of private precaution and
contamination of the floodwater. The models were applied in a municipality in east Germany, Eilenburg. It suffered extraordinary
damage during the flood of August 2002, which was well documented as were the inundation extent and depths. These data provide
an almost unique data set for the validation of flood risk analyses. The analysis shows that the combination of the 1D/2D
model and the meso-scale damage model FLEMOps+ performed best and provide the best compromise between data requirements, simulation
effort, and an acceptable accuracy of the results. The more detailed approaches suffered from complex model set-up, high data
requirements, and long computation times. 相似文献
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《Geoforum》2017
This article interrogates how social media can provide a platform for contesting dominant discourses. It does so through the lens of competitive eating, demonstrating that amateur competitive eaters use social media sites to challenge and subvert mass media representations of their sport while concomitantly upholding normative notions of healthy eating and bodies. Competitors consider themselves to be skilful athletes that discipline and train their bodies to eat. They regard their eating practices, which are often depicted in the mass media as uncontrolled and gluttonous, as controlled ingestion, and present an alternative perspective of their ‘sport’ – a perspective that stresses health, physical expertise and a fit, trained body over voracity and insatiability. Social media acts as a ‘precipitating agency’ for the creation of these alternative definitions of disciplined eating, as well as the construction of new digital eating identities. Instead of focusing on the food being ingested and the ‘Carnivalesque’ practice of competitive eating, we draw attention to the performers’ voices and the ways they attend to the mechanics of gurgitation, including methods of chewing, swallowing and stomach stretching, and their ability to manage, regulate and operate ingestivity. As hegemonic discourses align the notion of ‘good eating’ to discipline, order and restraint, competitive eating is thus revealed to be a practice that mirrors and appropriates, yet also ultimately reproduces, conventional narratives. Social media is, in turn, shown to be a political tool for counter-discursive practices that are produced in dialogue with, and concomitantly uphold and contest, normative discourses of mass media. 相似文献
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Warning systems are increasingly applied to reduce damage caused by different magnitudes of rockslides and rockfalls. In an integrated risk-management approach, the optimal risk mitigation strategy is identified by comparing the achieved effectiveness and cost; estimating the reliability of the warning system is the basis for such considerations. Here, we calculate the reliability and effectiveness of the warning system installed in Preonzo prior to a major rockfall in May 2012. “Reliability” is defined as the ability of the warning system to forecast the hazard event and to prevent damage. To be cost-effective, the warning system should forecast an event with a limited number of false alarms to avoid unnecessary costs for intervention measures. The analysis shows that to be reliable, warning systems should be designed as fail-safe constructions. They should incorporate components with low failure probabilities, high redundancy, have low warning thresholds, and additional control systems. In addition, the experts operating the warning system should have limited risk tolerance. In an additional hypothetical probabilistic analysis, we investigate the effect of the risk attitude of the decision makers and of the number of sensors on the probability of detecting the event and initiating a timely evacuation, as well as on the related intervention cost. The analysis demonstrates that quantitative assessments can support the identification of optimal warning system designs and decision criteria. 相似文献
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Agne P. Rustan 《Engineering Geology》1998,49(3-4):303-313
The optimal delay time between the contour holes in rock blasting has been studied by theoretical and empirical research in Sweden, regarding ground vibrations, increase in crack frequency, radial crack length and finally overbreak (half cast factor). The model test presented in this paper concerns controlled contour blasting in tunnelling and the full-scale blasts concern tunnelling, road cutting, and dimensional stone quarrying. The results indicate that the microsequential contour blasting technique (contour holes fired in sequence and with a delay in the order of 1–2 ms) is superior to simultaneous initiation both regarding blast-induced ground vibrations and crack frequency increase in the rock mass. Both these evaluation methods reflects the conditions deeper in the remaining rock mass. Simultaneous initiation, however, is superior to micro-sequential contour blasting both regarding the half cast factor and the length of radial cracks emanating from the blastholes. These two parameters are more related to the surface conditions after blasting. The industrial applications of this new knowledge are the use of micro-sequential contour blasting when ground vibrations are of greater concern than the contour, for example, in trench blasting or quarrying in urban areas, and the use of simultaneous initiation when an even rock surface is of high priority. 相似文献
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以泥盆系占优势的南秦岭成矿带中存在有重要的Ｐｂ－Ｚｎ－Ａｇ，Ａｕ，Ｈｇ－Ｓｂ及Ｃｕ矿床。它们形成中晚古生带扬子地块北部被动大陆边缘的沉积盆地演化与造山期中，成矿系列显示出时间与空间的演化特征，构在了一个热水沉积成矿系列，成矿发生于一个热旋回中，各种矿化有相似的物源，每一种地质事件都有特定的金属富集及富集在型和大型矿床是该地区构造－岩浆变质变形作用的最终产物。 相似文献
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GeoJournal - Building on the insights of scholarship highlighting specific aspects of the forming of place meanings and experiences during running (events), this paper aims at applying a more... 相似文献
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应用ＩＣＰ－ＭＳ法测定了岩石中的痕量Ｎｂ、Ｔａ、Ｚｒ、Ｈｆ、Ｔｈ、Ｕ，给出了检出限，并对酸溶和碱熔两种制样方法进行了对比实验。 相似文献
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Marie-PierreAubry WilliamA.Berggren JohnVanCouvering BrianMcGowran BradPillans FritsHilgen 《《幕》》2005,28(2):118-120
The long controversy over the term ‘Quaternary‘ as a chronostratigraphic unit may be reaching an apotheosis, judging from recent papers (Pillans and Naish, 2004; Gibbard et al., 2005; and referencest herein). The debate is no longer centered on whether there should be a place in the geological time scale for a unit termed ‘Quaternary‘-despite its dubious past, it cannot be denied that a large body of earth-historical research is strongly identified with this term. The challenge now concerns an appropriate rank and definition of Quaternary with regard to other chronostratigraphic units. Several options have been proposed (Pillans and Naish, 2004), and Gibbard et al. (2005) encourage a debate on these before decision is reached. In this brief note, we describe an arrangement not previously considered that seems advantageous. It is instructive, however, to first review the Pleistocene Series and Neogene System, the two units that are directly affected by introduction of the Quaternary into the chronostratigraphic hierarchy. 相似文献
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大陆漂移, 板块构造, 地质力学 总被引：2，自引：0，他引：2
本文简要地介绍了魏格纳大陆漂移说的主要内容及其提出的依据; 论述了在大陆漂移说的基础上, 由于海洋地质地球物理调查发现了大洋中脊、洋底扩张, 解释了大陆张裂的机制, 并建立了全球板块构造理论, 形成现代地学思想的革命; 李四光在大陆漂移说提出的同时已在积极地探讨和论述大陆地壳水平运动问题, 并结合中国大陆实际, 发展了陆内碰撞变形理论, 即包括全球大陆构造体系在内的地质力学理论和方法。他强调地质力学是一支脚站在地质上, 另一支脚站在力学上来研究地壳运动和变形现象。后来更扩大了其在资源、环境方面的应用。文章对魏格纳大陆漂移说、全球板块构造理论及地质力学三者的关系做了深入探讨, 论述了李四光地质力学理论方法的现代意义、超前意义, 提出要重视和发扬李四光留给中国人民的宝贵遗产, 建议深入学习李四光的著述, 结合地质调查新成果去丰富它和发展它。 相似文献
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We collected groundwaters in and around a large (313 Mt at 1.08% Cu and 0.3% cutoff) undisturbed porphyry copper deposit (Spence) in the hyperarid Atacama Desert of northern Chile, which is buried beneath 30–180 m of Miocene piedmont gravels. Groundwaters within and down-flow of the Spence deposit have elevated Se (up to 800 μg/l), Re (up to 31 μg/l), Mo (up to 475 μg/l) and As (up to 278 μg/l) concentrations compared to up-flow waters (interpreted to represent regional groundwater flow). In contrast, Cu is only elevated (up to 2036 μg/l) in groundwaters recovered from within the deposit; Cu concentrations are low down gradient of the deposit. The differential behavior of the metals/metalloids occurs because the former group dissolves as anions, enhancing their mobility, whereas the base metals dissolve as cations and are lost from solution most likely through adsorption to clay surface exchange sites and through formation of secondary copper chlorides, carbonates, and oxides. Most groundwaters within and down-flow of the deposit have Eh–pH values around the FeII/FeIII phase boundary, limiting the impact of Fe-oxyhydroxides on oxyanions mobility. Se, Re, Mo, and As are all mobile (with filtered/unfiltered samples ～ 1) to the limit of sampling 2 km down gradient from the deposit. The increase in ore-related metals, metalloids, and sulfate and decrease in sulfate–S isotope ratios (from values similar to regional salars, + 4 to + 8‰ δ34SCDT to lower values closer to hypogene sulfides, + 1 to + 4‰ δ34SCDT) is consistent with active water–rock reactions between saline groundwaters and the Spence deposit. It is likely that hypogene and/or supergene sulfides are being oxidized under the present groundwater conditions and mineral saturation calculations suggest that secondary copper minerals (antlerite, atacamite, malachite) may also be actively forming, suggesting that supergene and exotic copper mineralization is possible even under the present hyperarid climate of the Atacama Desert. 相似文献
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