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This essay serves as an introduction to this theme issue of GeoJournal and provides a framework for the contributed papers. Territoriality and scale, the essay argues, offer key analytics in approaching the spatiality of the ecological existence of human and non-human beings in their common `house' (oikos), thus of culture-nature relations generally. Such a focus, it bears emphasis, need not reproduce a naturalization of the modern culture-nature binary, but could, as is argued, remind `we moderns' that there is not only one nature (as little as there is only one culture), but a plurality of natures, which can serve the most varied of purposes. However, these spatialities do usually not and can very often not correspond to the spatialities of human activities, particularly to the territorialities and their orders/structures of scale in politico-administrative activities. The scalar literature within political geography, however, has for the most part seen its role as addressing human social relations in its analysis of contestations over power, space, and territory. A political ecology of scale, by contrast, will of necessity need to broaden the terrain of that discussion to include a variety of actors, human and non-human, involved in this broader network. Environmental conservation offers an important illustration of this problematic. A territorial, scalar, and non-modern understanding of ecological regimes is neccesary, argues this essay and the bundle of case studies that follow, because there is no `conservation' outside of a particular politics and geography of ecology. 相似文献
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Magnitude scale and quantification of earthquakes 总被引：1，自引：0，他引：1
Hiroo Kanamori 《Tectonophysics》1983,93(3-4)
Despite various shortcomings, the earthquake magnitude scale is one of the most fundamental earthquake source parameters to be used for catalogs. Although use of a uniform scale is desirable, it is not always possible because of changes in instrumentation, the data reduction method and the magnitude formula, the station distribution, etc. As a result, various magnitude scales have been developed and are currently in use. Recent developments in seismometry and earthquake source theories provide more quantitative source parameters than the magnitude. In order to maintain continuity and uniformity of the data, it is important to relate these magnitude scales and the new parameters. In view of this importance, relations between different magnitude scales are examined with an emphasis on the difference in the period of the waves used for the magnitude determination. Use of several magnitude scales determined at different periods provides a convenient method for characterizing earthquakes. The moment magnitude can be used to quantify both shallow and deep earthquakes on the basis of wave energy radiated, and provides a uniform scheme. 相似文献
4.
An algorithm is proposed for constructing a group (ensemble) pulsar time based on the application of optimal Wiener filters.
This algorithm makes it possible to separate the contributions of variations of the atomic time scale and of the pulsar rotation
to barycentric residual deviations of the pulse arrival times. The method is applied to observations of the pulsars PSR B1855+09
and PSR B1937+21, and is used to obtain corrections to UTC relative to the group pulsar time PTens. Direct comparison of the terrestial time TT(BIPM06) and the group pulsar time PTens shows that they disagree by no more than 0.4 ± 0.17 μs. Based on the fractional instability of the time difference TT(BIPM06)-PTens, σ
z
= (0.5 ± 2) × 10−15, a new limit for the energy density of the gravitational-wave background is established at the level Ω
g
h
2 ∼ 10−9. 相似文献
5.
V. M. Murthy 《Journal of Earth System Science》1999,108(4):317-320
Surface processes play an important role in the simulation of desertification and climate change. The present study shows
that enhancement of evaporation at a given place is due to surface temperature and wetness inhomogeneities compared to its
surroundings. Between any adjacent dry and wet strips the induced advective heat transport changes the available net radiation
between sensible and latent heat fluxes. It also accommodates a redistribution of surface energy between two adjacent inhomogeneous
surface strips. A combined model of Tarpley (1994) and Ya Guo and Schuepp (1994) about the advective heat transport over dry
and wet strips has been tested over Andhra Pradesh. Taking the Ananthpur district as a relatively drier region, the induced
transport over the rest of the districts is estimated. This study has been done for two monsoon seasons of 1990 and 1991.
Attempts are made to identify an indexing criteria based on this study to estimate the magnitude of the heat transport. 相似文献
6.
Tornadoes are the most destructive winds created by nature. Sometimes tornadoes are strong enough to destroy most things in their path. These types of tornadoes are few compared to all tornadoes confirmed/reported. Currently, existing scales describe severity levels in terms of intensity/magnitude, and they are not sufficient to clearly distinguish the severity level. Several discrepancies between various sources of information complicate the interpretation of trends in tornado data. As a solution to these inconsistencies, a technique is required to compare the severity level of tornadoes. Impact factors, such as the number of fatalities, number of injuries, number of homeless, affected population, affected area, and cost of damage, can be considered to evaluate the severity levels. Prior experience, preparedness, awareness, evolving technology, mitigation methods, and early warning systems may minimize the number of fatalities and injuries. Models are used to identify which of the above factors should be considered in a severity scale to indicate the seriousness of tornadoes. However, the lack of data prevents an in-depth analysis of tornado severity. Extreme value theory is used to study potential severity levels of tornadoes. This paper attempts to develop an initial severity scale for tornadoes, which is a primary stage to develop a multi-dimensional severity scale. This common scale provides the criteria to rank tornadoes and allows the impact of one tornado to be compared to the impact of another tornado. Further, the scale allows the impact of a tornado to be compared to any type of natural disaster that occurs. 相似文献
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Finn Løvholt Sylfest Glimsdal Carl B. Harbitz Natalia Zamora Farrokh Nadim Pascal Peduzzi Hy Dao Helge Smebye 《Earth》2012,110(1-4):58-73
In the aftermath of the 2004 Indian Ocean tsunami, a large increase in the activity of tsunami hazard and risk mapping is observed. Most of these are site-specific studies with detailed modelling of the run-up locally. However, fewer studies exist on the regional and global scale. Therefore, tsunamis have been omitted in previous global studies comparing different natural hazards. Here, we present a first global tsunami hazard and population exposure study. A key topic is the development of a simple and robust method for obtaining reasonable estimates of the maximum water level during tsunami inundation. This method is mainly based on plane wave linear hydrostatic transect simulations, and validation against results from a standard run-up model is given. The global hazard study is scenario based, focusing on tsunamis caused by megathrust earthquakes only, as the largest events will often contribute more to the risk than the smaller events. Tsunamis caused by non-seismic sources are omitted. Hazard maps are implemented by conducting a number of tsunami scenario simulations supplemented with findings from literature. The maps are further used to quantify the number of people exposed to tsunamis using the Landscan population data set. Because of the large geographical extents, quantifying the tsunami hazard assessment is focusing on overall trends. 相似文献
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W. A. Berggren L. H. Burckle M. B. Cita H. B. S. Cooke B. M. Funnell S. Gartner J. D. Hays J. P. Kennett N. D. Opdyke L. Pastouret N. J. Shackleton Y. Takayanagi 《Quaternary Research》1980,13(3):277-302
Nine first-appearance datums (FADs), twenty-three last-appearance datums (LADs), and three other micropaleontological datums are related to the magnetic-reversal, oxygen-isotope, and calcite-dissolution/coarse-fraction time scales to provide a preliminary basis for subdivision of the Quaternary in deep-sea sediments. The magnetic-reversal, oxygen-isotope, and calcite-dissolution/coarse-fraction scales have been correlated by determination on the same core materials, and absolute dates applied by 40K/40Ar or 14C dating of materials in known positions on one or another of these scales. FADS and LADs have been determined in cores for which either a magnetic-reversal, oxygen-isotope, or calcite-dissolution/coarse-fraction scale has also been available. Altogether 3 FADs and 5 LADs based on diatoms, 4 FADs and 5 LADs based on calcareous nannoplankton, 1 FAD and 8 LADs based on radiolarians, 1 FAD and 5 LADs based on planktonic foraminifers, 2 acme datums, and 1 ratio reversal datum have been determined, and absolute dates inferred by interpolation from known dates on the reference time scales. Some of the FADs and LADs apply or are synchronous only over limited areas of the oceans; others appear to be synchronous throughout the oceans. The base of the Quaternary is set at the top of the Olduvai event at 1.7 my. Four FADs, twelve LADs, two acme datums, and one ratio reversal datum occur above the base of the Quaternary at an average rate of about 1 per 100,000 yr. Five FADs and twelve LADs are recognized in the 0.8-my interval between the top of the Olduvai event and the Gauss/Matuyama Boundary at 2.5 my at an average incidence of about 1 per 50,000 yr. 相似文献
11.
裂隙网络模拟与REV尺度研究 总被引：4，自引：2，他引：2
研究了利用平面四边形模拟节理岩体三维裂隙网络的方法。在生成裂隙网络时,同时考虑结构面几何参数和力学参数的随机性。利用裂隙网络研究了确定岩体REV尺度的指标。在此基础上,编制了岩体裂隙网络模拟程序、裂隙网络图形输出程序和岩体REV尺度指标分析程序。通过算例分析,验证了研究成果及程序的合理性,并得出了岩体REV尺度约为各组裂隙中最大迹长期望值3~4倍的结论。研究成果为后续计算岩体等效力学参数奠定了基础。 相似文献
12.
Andrew S. Gale 《地学学报》1989,1(5):420-425
A detailed cyclostratigraphy is present in the rhythmically bedded Cenomanian hemipelagic chalks of the northern Anglo-Paris Basin, which can be correlated over 100,000 km2 . Individual decimetre-scale couplets probably represent the precession cycle (modes at 18 or 23 kyr), and can be readily grouped in sets averaging five, indicative of the short cycle of eccentricity (100 kyr). A composite cyclostratigraphy for the basin is presented here, and is used as the basis for a Cenomanian time-scale (20 and 100 kyr units). The total duration of the Cenomanian thus obtained (4.4 Myr) compares well with recent radiometric dates of 4.0–4.5 Myr. The time-scale is used to estimate the length of ammonite, inoceramid, and planktonic foraminiferal zones, the rates of formation of authigenic minerals (glauconite), sedimentation rates and the duration of transgressions and anoxic events. 相似文献
13.
Ulf Bayer 《International Journal of Earth Sciences》1989,78(1):155-169
The classical partial differential equation for compaction proves to provide a rather singular model, if the deformations caused by overload become reasonably large. An alternative model for compaction is derived by adapting an Eulerian view and by deriving the model equations from integral equations rather than from a priori differentiability assumptions. The result is not — as usual — a single partial differential equation, but an infinite set of differential equations, interesting in both mathematical and geological terms.Although there are still several simplifications and linearizations in the derived model, the model illustrates at least that the classical Terzaghi equation and mathematical models in its vicinity are highly idealized and probably instable, if applied to large scale systems.
相似文献
Zusammenfassung Die klassische partielle Differentialgleichung für die Kompaktion stellt ein sehr vereinfachtes Modell dar, zumindest für den Fall, daß die Deformationen infolge Auflast sehr groß werden. Hier wird ein alternatives Modell entwickelt, das nicht von der Voraussetzung der Differenzierbarkeit ausgeht, sondern über Integralgleichungen entwickelt wird, wobei die Eulersche Sicht des Raum-Zeitbezuges zur Anwendung kommt. Das Resultat ist dann nicht mehr eine einfache partielle Differentialgleichung, sondern ein unendliches System solcher Gleichungen.Obwohl auch das entwickelte Modell vereinfachte Annahmen erfordert und stark linearisiert, so verdeutlicht es doch zumindest, daß die klassische Therzaghi Gleichung und modifizierte Modelle, die auf diese Gleichung aufbauen, sehr wahrscheinlich instabil sind, wenn sie auf Systeme mit großen Deformationen angewandt werden.
Résumé L'équation classique aux dérivées partielles de la compaction fournit un modèle très simplifié, particulièrement dans le cas où les déformations dues à la surcharge deviennent considérables. L'auteur propose en alternative un modèle, adapté des conceptions eulériennes, qui repose sur les équations intégrales plutót que sur la présomption de différenciabilité. Le résultat n'est plus une simple équation aux dérivées partielles, mais un système infini de telles équations.Bien que le modèle présenté implique des hypothèses simplificatrices et des linéarisations, on peut néanmoins en déduire que l'équation classique de Terzaghi, ainsi que les modèles modifiés qui en découlent, sont très probablement instables s'ils sont appliqués à des systèmes à forte déformation.
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相似文献
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在大地电磁测深中由于噪声干扰常使得观测的信号发生畸变,严重地影响了信号的分析,因此如何有效地对噪声干扰进行滤波及怎样选择滤波时间尺度是当前数据处理中的难点。利用各向异性扩散(Anisotropic Diffusion,AD)及扩散平衡(Diffusion Balance,DB)方法在噪声压制与信号特征的保护及形态特征的恢复上达到了合理的平衡。模拟与实测数据显示:利用AD与DB可使平滑后的信号与原始信号达到高精度的逼近,信噪比从14.19 dB提高到69.25 dB;扩散平衡时间与噪声强度密切相关,噪声强度越高达到扩散平衡的时间越长;有效地压制了实测信号中的“飞点”干扰,恢复了信号的基本形态。 相似文献
15.
大型个体滑坡遥感调查 总被引：5，自引：2，他引：5
个体滑坡遥感调查是“数字滑坡”技术的一部分，其需要有更高地面分辨率的图像并与中等分辨率图像相结合，需精确的空间定位及与GIS技术相结合，以易贡滑坡及天台乡滑坡遥感调查为例说明其应用。采用RS＋GIS技术对易贡滑坡形态结构进行的最新研究证明高速滑体是飞行越过峡谷并在沟口碰撞解体后转变为碎屑流的，首次揭示了高速碎屑流的堆积结构，并由滑前块体及碎屑流堆积体计算证明了两者的转换关系。在天台乡滑坡遥感调查中提出了“滑坡特征点”法。由滑坡特征点的分析确定了滑坡边界及影响范围；计算了滑坡各部分的滑动距离、滑动方向和滑坡速度，滑坡规模。分析研究认为在2004年9月5日滑坡前，天台乡义和村总体上为一稳定斜坡，2003年开挖的新公路是该滑坡的潜在诱发因素。2004年9月3—5日的连续强降雨直接触发滑坡发生。 相似文献
16.
《Applied Geochemistry》2001,16(11-12):1291-1308
Land degradation and pollution caused by population pressure and economic development pose a threat to the sustainability of the earth's surface, especially in tropical regions where a long history of chemical weathering has made the surface environment particularly fragile. Systematic baseline geochemical data provide a means of monitoring the state of the environment and identifying problem areas. Regional surveys have already been carried out in some countries, and with increased national and international funding they can be extended to cover the rest of the land surface of the globe. Preparations have been made, under the auspices of the International Union of Geological Surveys (IUGS) and the International Association of Geochemistry and Cosmochemistry (IAGC) for the establishment of just such an integrated global database. 相似文献
17.
中国目前共发现并探明10超大型钼矿床,其成因类型全部属于斑岩型矿床。超大型钼矿床特点是:①全部位于古板块对接带的仰冲带一侧,属于被动的冒地槽单元外侧;②成矿母岩:a.岩石学名称绝大多数是花岗斑岩类;b.岩石化学:三高一低,即高酸、高碱、高钾、低钙镁的正常太平洋型钙碱性系列的超浅成侵入岩;c.岩石地球化学:Mo,W均为特富集元素,Cu,Pb,Zn则为中等富集,从而说明成矿物质主要来源于上地幔与下地壳的混熔体;从成矿母岩的成岩和成矿年代学方面可知,中国超大型钼矿床主要形成于中生代燕山白垩纪中、晚期。 相似文献
18.
Lydie Dupont 《Quaternary Science Reviews》2011,30(25-26):3589-3602
Palynological records of Middle and Late Pleistocene marine sediments off African shores is reviewed in order to reveal long-term patterns of vegetation change during climate cycles. Whether the transport of pollen and spores from the source areas on the continent to the ocean floor is mainly by wind or predominantly by rivers depends on the region. Despite the differences in transportation, accumulation rates in the marine sediments decline exponentially with distance to the shore. The marine sediments provide well-dated records presenting the vegetation history of the main biomes of western and southern Africa. The extent of different biomes varied with the climate changes of the glacial interglacial cycle. The Mediterranean forest area expanded during interglacials, the northern Saharan desert during glacials, and the semi-desert area in between during the transitions. In the sub-Saharan mountains ericaceous scrubland spread mainly during glacials and the mountainous forest area often increased during intermediate periods. Savannahs extended or shifted to lower latitudes during glacials. While the representation of the tropical rain forest fluctuated with summer insolation and precession, that of the subtropical biomes showed more obliquity variability or followed the pattern of glacial and interglacials. 相似文献
19.
L. De Chant 《Engineering Geology》1998,50(3-4):329-335
Folds and faults in the Devonian shales of the Berea area, Ohio have been analyzed on a small scale (several meters) to determine their method of formation. A simple elastic model has been developed to account for stress concentration due to lithostatic pressures induced by local relief. This analytical model is then coupled to the beam–column buckling stability theory. The possibility of failure due to faulting is also examined using the Coulomb criterion. Initial results indicate that local stresses due to topography are a probable cause of these structures, though the possible role of regional tectonic effects cannot be eliminated. The state of the local stress field and the possibility of seismic events have important implications for surface and subsurface design problems. 相似文献