Two-step interface and velocity inversion     

Xiao-Ling Lai  Xian-Kang Zhang  Xu-Yao Zheng 《地震学报(英文版)》1998,11(6):687-697

This paper studies the computation method of two-step inversion of interface and velocity in a region. The 3-D interface is described by a segmented incomplete polynomial; while the reconstruction of 3-D velocity is accomplished by the principle of least squares in functional space. The computation is carried out in two steps. The first step is to inverse the shape of 3-D interface; while the second step is to do 3-D velocity inversion by distributing the remaining residual errors of travel time in accordance with their weights. The data of seismic sounding in the Tangshan-Luanxian seismic region are processed, from which the 3-D structural form in depth of the Tangshan seismic region and the 3-D velocity distribution in the crust below the Tangshan-Luanxian seismic region are obtained. The result shows that the deep 3-D structure in the Tangshan seismic region trends NE on the whole and the structure sandwiched between the NE-trending Fengtai-Yejituo fault and the NE-trending Tangshan fault is an uplifted zone of the Moho. In the 3-D velocity structure of middle-lower crust below that region, there is an obvious belt of low-velocity anomaly to exist along the NE-trending Tangshan fault, the position of which tallies with that of the Tangshan seismicity belt. The larger block of low-velocity anomaly near Shaheyi corresponds to a denser earthquake distribution. In that region, there is an NW-trending belt of high-velocity anomaly, probably a buried fault zone. The lower crust below the epicentral region of the Tangshan M _S=7.8 earthquake is a place where the NE-trending belt of low-velocity anomaly meets the NW-trending belt of high-velocity anomaly. The two sets of structures had played an important role in controlling the preparation and occurrence of the M _S=7.8 Tangshan earthquake. Contribution RCEG97006, Research Center of Exploration Geophysics, China Seismological Bureau, China. This project is supported by the Chinese Joint Seismological Science Foundation.  相似文献   

爆破振动对铁厂沟村房屋选择性破坏的调查与分析   总被引：2，自引：1，他引：1  

杨纪林  吕桂林 《内陆地震》1998,12(4):349-354

乌鲁木齐矿务局露天矿的剥离爆破对距爆点１ｋｍ外的铁厂沟材房屋产生了选择性破坏,振动对个体房屋的破坏呈现出鲜明的选择性,不同房屋遭受的破坏程度差异极大。  相似文献   

湖水-沉积物界面内源物质交换动态复水模拟研究   总被引：7，自引：0，他引：7       下载免费PDF全文

薛联青  吕锡武  吴磊 《水科学进展》2004,15(2):189-192

分布式采集了玄武湖底长期暴露的底泥,分析了底泥营养物的分层分布及其理化特性对湖泊水质的影响强度。通过动态换水试验,研究了复水过程中暴露底泥营养盐的释放过程和上覆水总磷、总氮浓度变化对水土界面物质交换的作用关系以及对水体富营养化程度的影响机制。实验及模拟表明:由于湖泥表层长期暴露,有机及结合态营养盐降解为无机态营养盐,即使复水过程中使用清水,但由于干涸湖床沉积物总磷T-P、总氮T-N的垂直分布,也将严重导致内源营养盐释放总量持续增加,在相对长时间内,上覆水总磷浓度仍维持在较高(01mg/L)水平。研究成果为实施生态修复,治理复水后湖体富营养化提供了理论和实验依据。  相似文献   

黄河小花区间暴雨径流过程分布式模拟   总被引：5，自引：4，他引：5       下载免费PDF全文

吴险峰  刘昌明  郝芳华  王国强  杨桂莲 《水科学进展》2004,15(4):511-516

提出了一种松散偶合型结构的分布式水文模型,模型以小时为时段,主要用于洪水模拟。模型构建在DEM的基础上,由数字流域、单元网格模型、河网汇流模型、水库调蓄模型和图形用户界面(GUI)等5部分构成。通过GUI可以实现模型的输入、参数选择和运行输出。模型适用于人类活动较少的、半湿润和半干旱地区,在黄河小浪底-花园口区间洛河卢氏以上流域得到应用。  相似文献   

碳酸盐岩风化壳岩-土界面地球化学特征及其形成过程--以贵州花溪灰岩风化壳剖面为例   总被引：26，自引：4，他引：26  

孙承兴  王世杰  刘秀明  冯志刚 《矿物学报》2002,22(2):126-132

在对黔中花溪灰岩风化壳原地风化残积特征进行了论证的基础上，本文从地球化学角度对央酸盐岩风化壳岩-土界面发育特征及其形成机理进行了讨论。碳酸盐岩的易溶解性和显著的差异性溶蚀，导致了其风化壳基岩面起伏强烈、岩-土界面界线清楚且突变；与此宏观特征相对应的是风化产物的矿物成分、主量、微量元素等方面均存在明显的突变现象。同时，在岩-土界面土层中形成了一个相对狭窄而突变的碱性障，此障无疑对风化壳的一些地质地球化学过程产生强烈影响，例如硅酸盐矿物的进一步蚀变分解，以及稀土和其它部分微量元素的超常富集和强烈分异等。  相似文献   

The interaction of elastic waves with a solid-liquid interface,with applications to the core-mantle boundary     

D. J. Doornbos  J. C. Mondt 《Pure and Applied Geophysics》1980,118(2):1293-1309

The paper discusses basic ideas and principles underlying methods, which have proved useful in the interpretation of diffraction and scattering phenomena by a smooth or slightly rough solid-liquid interface. Generally, the wave interaction may be formulated as an excitation problem; it involves (1) finding an equivalent dislocation or source distribution on the interface, and (2) evaluating the excited wave field. These steps are taken through perturbation theory and/or adopting the appropriate generalization of ray theory. In this context an explicit form of Green's function is also given. The methods have been applied to the core-mantle boundary, with a view toward the interpretation of recent data: (a) diffracted P and S waves around the core (in particular, their attenuation); (b) scattered short-period core phases (in particular, precursors to PKP and PKKP). Other types of wave interaction, and implications for models of the core-mantle boundary structure, are briefly mentioned.Paper presented at the EGS/ESC workshop on Generation and propagation of seismic waves in Neustadt, Federal Republic of Germany, August 1978.  相似文献   

Rock-weathering by lichens in Antarctic: patterns and mechanisms     

Chen Jie Ph.D.  Hans-Peter Blume 《地理学报(英文版)》2002,12(4):387-396

Saxicolous species of lichens are able to induce and accelerate weathering of their rock substrate, and effects of lichens on substrate can be attributed to both physical and chemical causes. This paper is focused on biotic weathering actions of epilithic and endolithic species on the different rock types (sandstones and volcanogenic rocks) in Antarctica. The patterns, mechanisms, processes and neoformations of rock-weathering resulting from lichen colonization are expounded in detail. Furthermore, it is pointed out that, for a better understanding of the impacts of lichens on environments, the studies on the rate of biotic weathering and the comprehensive involvement of the lichen effects on weathering of natural rocks remain to be carried out in Antarctica.  相似文献   

金刚石焊接机理的理论分析(金刚石焊接机理研究之四)          下载免费PDF全文

李岳 《探矿工程》2001,(4):58-61

通过物质之间的浸润与扩散理论，从物质的离子、电子结构诸方面对金刚石表面金属碳化物形成的可能性与原理进行论证。为分析解释金属碳化物形成及金刚石的焊接机理提供了理论依据。  相似文献   

溆浦陆相红盆地质特征及其演化探讨     

李福顺 《湖南地质》2001,20(1):1-4

本文根据构造－岩性－岩相法，将涂浦红盆划分为5个岩组，4类构造界面，2个二级层序地层，进而探讨了该陆相红盆的演化特征。  相似文献   

可视化技术在地图学中的应用   总被引：9，自引：2，他引：9  

王卉  李爱光 《测绘学院学报》2001,18(1):59-62

着重介绍了可视化技术在地图学中的应用，并围绕如何设计一个友好的人机交互系统，从可视化编程语言，用户界面可视化，地图的动态可高化设计以及人的视觉效果等4个方面阐述了可视化技术在地图学中应用的新焦点。  相似文献