基于GIS的长江三峡水库诱发地震预测数据库构建   总被引：3，自引：0，他引：3       下载免费PDF全文

张秋文  李安然  王乘  张国安 《地震地质》2003,25(2):338-347

从系统需求分析出发 ,介绍了可视化的长江三峡水库诱发地震预测数据库构建的主要内容及其实施技术路线 ,划分了国内外典型的诱震震例以及长江三峡地区基础地理、诱震地质环境和诱发地震前兆监测等相关基础信息的主要类型 ,确定了各类信息的数据库结构和数据格式。在此基础上 ,对各类基础图形进行数字化处理 ,建立了可视化的图形数据库 ;通过其相关属性信息的录入或转换 ,建立了各类图形相应的属性数据库 ;利用GIS技术 ,对图形数据库及其属性数据库进行了无缝集成 ,实现了图形数据与其相应属性数据间的可视化交互式查询、浏览、管理和分析  相似文献   

Structural interpretation of the Marmara region, NW Turkey, from aeromagnetic, seismic and gravity data     

A. Ates  T. Kay&#x;ran  I. Sincer 《Tectonophysics》2003,367(1-2):41-99

The seismically active Marmara region, located in NW Turkey, lies on the westward end of the North Anatolian Fault (NAF). The NAF is well defined on land. Previous investigations of its extension in the Marmara Sea include marine bathymetry, seismological activity and seismic profiles. In this study, faults and their configurations identified inland are extended into the Marmara Sea by means of aeromagnetic anomalies, as well as seismic and gravity profiles. The deep structure was resolved by constructing a map of the Tertiary bottom. Shallow Curie isotherm was determined by spectral analysis, indicating a thinner crust in the northern Marmara depression area with respect to the continental crust. A combination of the geophysical data allows us to propose the existence of subsidence and isostatic equilibrium in the northern Marmara Sea. A less-active zone identified in the central high zone dividing the Marmara Sea into two parts may also be deduced from the seismic data. This structural arrangement may play a key role in earthquakes that will affect the surrounding regions.  相似文献   

Holocene lake-level changes and their reflection in the paleolimnological records of two lakes in northern Estonia   总被引：1，自引：0，他引：1  

Jaan-Mati Punning  Mihkel Kangur  Tiiu Koff  Göran Possnert 《Journal of Paleolimnology》2003,29(2):167-178

Sediment cores from two neighbouring lakes (Viitna Linajärv and Viitna Pikkjärv) in northern Estonia were studied to determine lake-level fluctuations during the Holocene and their impact on biogeochemical cycling. Organic matter and pollen records dated by radiocarbon and radiolead indicated a water level rise in both lakes during the early Holocene (c. 10 000–8000 BP). A regression followed around 7500 BP and several transgressions occurred during the latter half of the Holocene, c. 6500 and 3000 BP. Human impact during the last centuries has caused short-term lake-level fluctuations and accelerated sediment accumulation in the lakes. The differences in water depth led to variations in sediment formation. During 10 000–8000 BP (Preboreal and Boreal chronozones) mineral-rich sediments with coloured interlayers deposited in L. Linajärv. These sediments indicate intensive erosion from the catchment and oxygen-rich lake, which favoured precipitation of iron oxides and carbonates. Fluctuations in water depth, leaching of nutrients from catchment soils and climatic changes increased the trophy of L. Linajärv around 6000 BP. The subsequent accumulation of gyttja, the absence of CaCO₃ and the decrease in both the C/N ratio and phosphorus content in the sediments also indicate anoxic conditions in the hypolimnion. The similarity in the development of L. Linajärv and L. Pikkjärv and their proximity made it possible to discern the impact of water depths changes on biogeochemical cycling in lakes.  相似文献   

Comparison of azimuthal seismic anisotropy from surface waves and finite strain from global mantle-circulation models     

Thorsten W. Becker  James B. Kellogg  Göran Ekström  Richard J. O'Connell 《Geophysical Journal International》2003,155(2):696-714

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中国大陆强震时空关联特征的初步定量研究——西南、西北地区     

刘文兵  陈化然  张国民 《地震》2001,21(3):77-84

根据我国大陆强震成组孕震的特征、以强震诱发理论为基础，对我国近30年来西南地区和西北地区Ms≥7.0的强震进行At值扫描，并对它们作出了简要的分析和R值评分，并依此作出了预测实践，对今后一段时间我国地震危险区进行了讨论。  相似文献   

Seismotectonic re-evaluation of the 1976 Friuli, Italy, seismic sequence     

Silvia Pondrelli  Göran Ekström  Andrea Morelli 《Journal of Seismology》2001,5(1):73-83

The 1976 Friuli seismic sequence is known for itscomplexity, with several unusually large aftershocksoccurring in the epicentral area. The source region, where the northeastern part of the Alpine chain meetsthe northern Dinaric chain, is characterized by a complexcompressional tectonic regime. Previous studies have not clearly identified which of the two main tectonic systems was activated, in part due to the limited precision of derived earthquake parameters, such as hypocentral coordinates and focal mechanisms. We review the locations for the 10 largest events of the sequence, including theSeptember 16, 1977 and April 18, 1979 earthquakes andwe compute their centroid moment tensors. Source parameters are calculated using intermediate period surfacewaves and the modification of the Harvard centroid-moment tensoralgorithm proposed by Arvidsson and Ekström (1998). A summary of all available geological, geodetic and seismological data show that most of the earthquakes may be associated with the Periadriatic overthrust and other related thrust faults. Based on their locations and focal mechanisms only two ofthe early aftershocks (May 7, 1976 and May 9, 1976) appear instead to have occurred on Dinaric structures.  相似文献   

陕甘川邻接区基于MAPGIS的金成矿远景区预测   总被引：9，自引：0，他引：9  

曾佐勋  周继彬等 《地学前缘》2001,8(2):415-420

陕甘川邻接区金矿床的展布与滑脱挤出构造、特别是不均匀滑脱关系非常密切。为了定量分析不均匀滑脱与金矿的关系 ,专门研制了自动追踪断裂求取弧形滑脱断裂曲率的计算机软件。经MAPGIS空间分析和多次实验证实 ,区内大中型以上金矿与曲率大于 4的点的密度区关系密切。用Grsip软件 ,对研究区进行断裂密度统计 ,再与金矿床进行MAPGIS空间分析 ,发现断裂密度在 10 0 2 40时 ,对金矿最有利。将研究区的印支—燕山期岩体依出露面积大小划分了大、中、小岩体和岩脉 4种规模的侵入岩。对侵入岩与金矿床MAPGIS空间分析 ,得出了中、小型岩体和岩脉的成矿有利区间分别为岩体边界向外扩展 70 ,6 0和 40个MAPGIS单位的环带。在进行MAPGIS空间分析过程中 ,还分析出研究区的金矿与该区应力异常区也有密切关系 ,但金矿与地层的关系不密切。最后 ,利用MAPGIS空间分析工具对陕甘川邻接区以上金成矿有利因素进行相交分析 ,圈定出 14个一级金矿远景区 ,19个二级金矿远景区和 11个三级金矿远景区。  相似文献   

孝妇河源头地区岩溶地下水资源可持续利用的决策支持研究   总被引：2，自引：1，他引：2  

王浩然  王敏  朱国荣 《水文地质工程地质》2001,28(5):32-34,57

基于运筹学和系统工程学的基本理论，建立了地下水最优控制模型，并采用微分动态规划方法进行求解，最后直接根据淄博市孝妇河源头地区地下水资源的可持续利用需求，建立了该区的地下水最优控制模型，并求得了最优解。  相似文献   

Upper layer circulation of the Nordic seas as inferred from the spatial distribution of heat and freshwater content and potential energy   总被引：1，自引：0，他引：1  

Göran Björk  Bo G. Gustafsson  ers Stigebrandt 《Polar research》2001,20(2):161-168

The spatial distribution of heat and freshwater content and potential energy of a several hundred metre thick surface layer are computed for the Nordic seas and adjacent parts of the northern North Atlantic and the Arctic Ocean using a total of almost 100 000 hydrographic stations. The fields clearly show the major features of the area's circulation, with warm salty water in the eastern part and fresher, colder water in the western part. Comparisons with published estimates show that the potential energy field, representing the baroclinic part of the flow, accounts for about 30 % of the total flow but roughly 100 % of the flow of Polar Water in the northern part of the East Greenland Current, about 50 % of the total flow in the Norwegian Atlantic Current, and just a small fraction of the flow in the eastern part of Fram Strait. This suggests that the barotropic circulation is quite important in many parts of the Nordic seas. The barotropic circulation is also clearly seen by its effects on the integrated fields with isolines following deep bathymetric contours. We speculate that the barotropic circulation in combination with topographic obstacles, like the Greenland–Scotland Ridge and the ridge system in the Jan Mayen area, may have large impact on the spreading of freshwater and heat in the Nordic seas.  相似文献   

A water zone propagating through a permeable rock     

Göran Rehbinder 《Rock Mechanics and Rock Engineering》1977,9(4):245-253

SummaryA Water Zone Propagating Through a Permeable Rock A one-dimensional front of a water zone penetrating an initially dry permeable medium is studied theoretically as well as experimentally. The theory includes the case when the permeability varies with position. Simple experiment and theory show that the front of the water zone increases as the square root of time if the permeability is constant. A method is suggested to measure the non-constant permeability by measuring the penetration rate.

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ZusammenfassungAusbreitung einer Wasserzone im durchlässigen Fels Eine Front von einer Wasserzone, die durch ein permeables eindimensionales Medium dringt, ist genau beobachtet worden, sowohl theoretisch als auch experimentell. Die Theorie beinhaltet den Fall, daß die Permeabilität nicht konstant ist, sondern mit der Lagekoordinate wechselt. Einfache Experimente und Theorien beweisen, daß die Lage der Front der Wasserzone mit der Quadratwurzel der Zeit erweitert wird, wenn die Permeabilität konstant ist. Eine Methode wird vorgeschlagen, wie man die variable Permeabilität durch das Messen der Eindringungsgeschwindigkeit mißt.

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RésuméExtension d'une zone d'eau dans une roche perméable Un front d'une zone d'eau, pénétrant un milieu perméable et à une dimension, a été étudié non seulement théoriquement mais encore expérimentalement. La théorie comprend le cas où la perméabilité n'est pas constante mais met de la variété avec les coordonnées. De simples expériences et des théories donnent que la position du front de la zone d'eau augmente comme la racine du temps si la perméabilité est constante. Un procédé proposé est que l'on mesure la perméabilité d'un variable à force de mesurer la vitesse de la pénétration.

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Nomenclature g gravity acceleration m/s² - k reciprocal reference length m^–1 - L length of rock specimen m - p pressure Pa - p0 reference pressure Pa - R position of the front of the water zone m - t time s - u velocity of water m/s - x position coordinate m - permeability m² - ₀ reference permeability m² - viscosity of water Ns/m² - integration variable m - density of water kg/m³ With 6 Figures  相似文献