根据GPS数据的北天山现代构造活动概率区研究     

E.H. 努西波夫  М.М.拉赫美巴耶夫  A.B.祖博维奇  O.И.莫先柯  Г.Г.谢洛契科夫  Ю.Г.谢尔巴  陈保华 《内陆地震》2007,21(2):170-176

根据GPS数据的现代运动场研究了北天山的现代形变过程。在这一地区,速率分量和某些类型形变速率场的不均性都表现出与现代构造活动区密切相关。以场的水平梯度极值区图为基础划分构造活动区段,查明强震震中区就位于这些活动区。当取得活动区状态的GPS数据时,区域地壳动力学状态监测是最有效的。  相似文献   

糜棱岩化过程中矿物变形温度计   总被引：17，自引：0，他引：17  

向必伟  朱光  王勇生  谢成龙  胡召齐 《地球科学进展》2007,22(2):126-135

对有效确定中—低温下糜棱岩变形温度一直以来都没有比较理想的方法，而在研究韧性剪切带过程中对其变形温度的确定又常是必不可少的。根据近年来国际上对天然石英、长石、方解石等矿物变形的研究成果，总结了利用矿物变形指示变形温度的方法。在不同的温度条件下，长石与石英的变形方式具有阶段性，其变形与动态重结晶型式与温度具有明显的对应关系。石英变形中的滑移系及其C 轴组构图主要受变形温度的控制。低温变形中的方解石e 双晶纹形态也与温度呈密切的相关性。观测这些矿物变形的显微构造，可以很好地估计韧性剪切带糜棱岩化过程中的变形温度。  相似文献   

石河子跨断层形变资料的地震异常初析     

陈伟  邢佑宏  郭卫英  王在华 《内陆地震》2006,20(3):276-281

利用石河子跨断层水平向的整点值观测数据,采用动态分析方法,对2003年以来石河子周边200 km内发生的MS≥4.0地震进行了回顾性分析。发现了一些有意义的异常现象,主要异常形态有两种:一是节律性的脉冲式波动,这种异常一般持续4~10天,异常结束后5~80天发震;二是快速阶跃与平静交替,该异常一般持续5~40天,异常结束后数小时内发震。不同的异常类型可能与地震的大小、震中距的远近以及构造环境有关。  相似文献   

青海省哇洪山断裂带中段构造变形特征及X光岩组分析   总被引：3，自引：0，他引：3  

张拴宏  周显强 《大地构造与成矿学》2003,27(1):29-36

通过对哇洪山断裂带中段构造变形宏观及微观特征的研究,认为该断裂带经历了两种不同层次、不同性质的构造变形,早期以韧性变形为主,形成了沿断裂带广泛分布的NW-NNW向糜棱岩带;晚期以脆性变形为主,形成了广泛分布断层破碎带,并将早期的糜棱岩带错断。X光岩组分析结果表明,糜棱岩带构造岩内矿物排列定向性明显,其中石英变形以底面滑移或近底面滑移为主,兼有柱面滑移,为中低温-中温变形环境所形成;另外动态重结晶对变形岩石中石英优选方位的形成也可能发挥了重要作用。华里西晚期花岗闪长岩、印支期钾长花岗岩、花岗岩、二长花岗岩均没有明显的优选方位,因此韧性变形发生在该类岩石侵位之前。构造变形分析及同位素测年结果证实韧性剪切带形成于晚志留世,即加里东晚期。  相似文献   

基于SIMULINK的框架结构非线性地震反应仿真   总被引：3，自引：0，他引：3  

李英民  刘育博  夏洪流 《世界地震工程》2003,19(3):28-34

针对现有非线性动力分析程序的可视化和二次开发能力不强的特点，以SIMULINK为平台建立了层间剪切模型和平面杆系模型的非线性地震反应仿真模型，通过两个算例分析验证了模型的正确性，指出了基于SIMULINK的结构非线性地震反应仿真的优势。  相似文献   

基于神经网络的结构地震反应仿真   总被引：2，自引：0，他引：2  

吴波  李英民 《世界地震工程》2003,19(3):144-149

提出了基于神经网络的结构地震反应仿真方法，探讨了仿真基本步骤中样本集的准备、目标函数的选取、网络拓扑结构的构建、隐层神经元数目的确定、训练方法的选择以及提高泛化精度的措施等若干实际问题，并通过算例分析验证了本方法的可行性。  相似文献   

Poroelasticity: observations of anomalous near surface tilt induced by ground water pumping     

M. Fabian  H.-J. Kümpel 《Journal of Hydrology》2003,281(3):187-205

Ground tilt signals observed at three different test sites in Germany confirm earlier observations of surface deformation occurences caused by the withdrawal of ground water from nearby wells. The strength of the signals presented here ranges from a few μrad to 230 μrad, whereby ground tilt was measured in shallow boreholes, at depths between 2 and 4 m. Analysis of the tilt signals suggests that local inhomogeneities in the subsoil can have significant impact on several signal parameters, namely its maximum amplitude, its variation in time, and its strike with respect to the direction of the productive well. The observed data emphasize the likelihood of various causes for deviations from the ‘normal’ tilt response that holds for an isotropic poroelastic half-space. In particular, at one site, a reverse well level change, also known as ‘Noordbergum effect’ in hydrogeology, is seen together with a respective response in the tilt signal. The study concludes that near surface deformation in the vicinity of pumped wells bears a wealth of information that may be useful to constrain the conditions of fluid flow at depth; and that there is a need for model calculations to fully understand the involved phenomena.  相似文献   

强震前形变异常的时空演化特征     

宋先月  宋治平  武安绪  薛艳  倪友忠 《地震》2003,23(2):70-76

主要对华北北部地区的1989年大同地震、1991年大同地震及1998年张北地震3次强震前的形变异常时空演化特征进行了研究。结果表明，若以形变异常的开始时间作为判断标准，形变异常的群体频次在强震前1～2年内均出现高于或接近2倍均方差的高值状态，显示出形变异常的中期异常，异常时空演化的三阶段特征表现不明显。若以形变异常的转折时间(或结束时间)作为异常判断标准，形变异常频次在震前1～4个月达到高值，显示出异常的短临信息，并且，形变异常的时空演化过程存在明显的三阶段(α、β、γ)特征。在对这些特征进行理论分析的基础上，提出了将形变异常的开始时间与转折时间分别作为判断标准，如果两种群体频次均处于异常状态，则表明异常已处于从中期向短期过渡的阶段，反之，异常仍处于中期阶段。这种形变异常的分析思路可作为形变异常从中期阶段向短期阶段过渡的一种判断方法。  相似文献   

The use of surface monitoring data for the interpretation of landslide movement patterns   总被引：4，自引：1，他引：4  

D.N. Petley  F. Mantovani  M.H. Bulmer  A. Zannoni 《Geomorphology》2005,66(1-4):133

The Tessina landslide is a large, seasonally active slope failure located on the southern slopes of Mt. Teverone, in the Alpago valley of NE Italy, consisting of a complex system that has developed in Tertiary Flysch deposits. The landslide, which first became active in 1960, threatens two villages and is hence subject to detailed monitoring, with high quality data being collected using piezometers, inclinometers, extensometers, and through the use of a highly innovative, automated Electronic Distance Measurement (EDM) system, which surveys the location of a large number of reflector targets once every 6 h. These systems form the basis of a warning system that protects the villages, but they also provide a very valuable insight into the patterns of movement of the landslide.In this paper, analysis is presented of the movement of the landslide, concentrating on the EDM dataset, which provides a remarkable record of surface displacement patterns. It is proposed that four distinct movement patterns can be established, which correspond closely to independently defined morphological assessments of the landslide complex. Any given block of material transitions through the four phases of movement as it progresses down the landslide, with the style of movement being controlled primarily by the groundwater conditions. The analysis is augmented with modelling of the landslide, undertaken using the Itasca FLAC code. The modelling suggests that different landslide patterns are observed for different parts of the landslide, primarily as a result of variations in the groundwater conditions. The model suggests that when a movement event occurs, displacements occur initially at the toe of the landslide, then retrogress upslope.  相似文献   

A fertile harzburgite–garnet lherzolite transition: possible inferences for the roles of strain and metasomatism in upper mantle peridotites     

J.B. Dawson   《Lithos》2004,77(1-4):553-569

Porphyroclastic enstatite in a garnet lherzolite xenolith from the Monastery Mine kimberlite, South Africa, has exsolved pyrope garnet, Cr-diopside and Al-chromite, and the specimen is interpreted as representing a transition from fertile harzburgite, (containing high Ca-Al-Cr enstatite) to granular garnet lherzolite. Although the exsolved phases occur in morphologically different forms (fine and coarse lamellae; equant, ripened grains), indicating textural disequilibrium, the exsolved grains are very constant in composition, indicating chemical equilibrium. Theoretically, the exsolution could have been due to a fall in temperature, but the close association of exsolution and deformation of the host enstatite suggests that exsolution was also aided by straining of the enstatite lattice. The phase compositions can be broadly matched with those in other mantle peridotites, except that all phases are characterised by a virtual absence of Ti. In the garnet and diopside Ti, Co, Zr and most of the REE are lower than in published analyses of garnet and diopside in both granular and sheared garnet lherzolites from Southern African kimberlites, and diopside/garnet partitioning for Sr and the REE is higher. Comparison with the trace element chemistry of an enstatite from a fertile harzburgite indicates that, except for Nb, the trace element content and distribution found in the Monastery phases could arise by isochemical exsolution from such an enstatite. On the assumption that (a) the Monastery specimen represents a transition from harzburgite to garnet lherzolite, and (b) many garnet lherzolites are of exsolution origin (as suggested by their modal compositions), the inference is that most garnet lherzolites, and not just the sheared variety, have been subject to varying degrees of Ti, Zr, Sr and REE metasomatism.  相似文献