雅江地块的震兆分析与强震危险性探讨     

程万正 《内陆地震》2004,18(1):20-28

分析了雅江地块的构造环境、地震活动和震兆异常，探讨2001年雅江6．0级地震、2002年新龙5．3级地震发生后雅江地块的强震趋势。重点对理塘-德巫断裂带，新龙、白玉、德格及贡觉一带地区的异常地震活动图像进行分析，认为该区存在强震填空的潜在危险性。  相似文献   

安徽淮河构造变形带及邻近块体现代构造应力场特征   总被引：3，自引：1，他引：3  

刘东旺  刘泽民  沈小七  夏瑞良  李敏莉  闫素萍  凌学书 《中国地震》2004,20(4):364-371

针对安徽省较特殊的构造环境及历史地震分布特点，利用直达波最大振幅比和系统聚类分析方法，在对安徽淮河中游区1974年以来近百个中小地震震源机制反演、聚类及空间合成的基础上，分析了华北断块南缘的安徽淮河构造变形带及邻近块体震源断层滑动方式、构造应力场分布及块体运动方式、应力场随时间变化等。结果显示：淮河构造变形带及其邻近块体上震源断层总体上以近走滑型或斜滑型破裂为主，但倾滑型破裂也占一定比例；该地区构造应力以水平作用为主，但也存在一定的垂向作用。其中淮北和皖中块体仍可能分别向SWW和NEE方向运动，并在淮河构造变形带上产生左旋剪切作用，呈现一定的继承性活动特征；各块(带)上主压应力P轴走向随时间的变化在总体上较为一致，而各时段之间P轴方位存在一定差异，显示安徽淮河中游区受华北和华南应力场的共同作用，但其地震活动可能主要受控于华北应力场。  相似文献   

川西北倒三角形断块东部区域强震带形成机制与地震活动特征     

蒋良文  王士天  李渝生  王运生 《地球科学进展》2004,(Z1)

川西北倒三角形断块东部区域地处青藏高原东部边缘地带,地跨川西北高原及其与四川盆地过渡带的高山峡谷区,属我国著名的南北向地震带的中段,因其特定的大地构造环境和强烈的现代地壳构造运动,导致其在强大的近东西向构造应力场的驱动和平卧“A”字型控震构造体系的控制下,沿两侧边界断裂向东强力楔入,于“构造急剧收口带”之西侧形成了一个近SN向地跨三大构造单元的强震带,强震沿该带有规律的往返迁移和重复发生,且地震活动强弱具有较明显的分形特征。  相似文献   

Horizontal crustal movement in Chinese mainland from 1999 to 2001     

Gu Guo-hua  Fu Yang  Wang Wu-xing 《地震学报(英文版)》2004,17(1):52-60

The paper introduces the horizontal crustal movement obtained from GPS observations in the regional networks (including the basic network and the fiducial network) of the Crustal Movement Observation Network of China (CMONOC) carried out in 1999 and 2001. This paper is characterized by the acquisition of the horizontal displacement velocities during the period from 1999 to 2001 at the observation stations in the regional networks with datum definition of a group of stable stations with small mutual displacements in east China. Based on the most detailed map of horizontal crustal movement in Chinese mainland, the division of blocks, their displacements and deformations are studied. An approach to analysis of the intensity of the horizontal crustal deformation is proposed. The general characteristics of the recent horizontal crustal movement in Chinese mainland and that before the Kunlunshan earthquake of M=8.1 on November 14, 2001 are analyzed. Foundation item: The National Development and Programming Project for Key Basic Research (95-13-03-07).  相似文献   

Molecular modeling of the 10-Å phase at subduction zone conditions     

Jianwei Wang 《Earth and Planetary Science Letters》2004,222(2):517-527

Molecular dynamics (MD) modeling of the 10-Å phase, Mg₃Si₄O₁₀(OH)₂·xH₂O, with x=2/3, 1.0 and 2.0 shows complex structural changes with pressure, temperature and water content and provides new insight into the structures and stabilization of these phases under subduction zone conditions. The structure(s) of this phase and its role as a reservoir of water in the mantle have been controversial, and these calculations provide specific predictions that can be tested by in situ diffraction studies. At ambient conditions, the computed structures of talc (x=0) and the 10-Å phases with x=2/3 and 1.0 are stable over the 350-ps period of the MD simulations. Under these conditions, the 10-Å phases show phlogopite-like layer stacking in good agreement with previously published structures based on powder X-ray diffraction data for samples quenched from high-pressure and high-temperature experiments. The calculations show that the 10-Å phase with x=2.0 is unstable at ambient conditions. The computed structures at P=5.5 GPa and T=750 K, well within the known stability field of the 10-Å phase, change significantly with water content, reflecting changing H-bonding configurations. For x=2/3, the layer stacking is talc-like, and for x=1.0, it is phlogopite-like. The calculations show that transformation between these two stackings occurs readily, and that the talc-like stacking for the x=2/3 composition is unlikely to be quenchable to ambient conditions. For x=2.0, the layer stacking at P=5.5 GPa and T=750 K is different than any previously proposed structure for a 10-Å phase. In this structure, the neighboring basal oxygens of adjacent magnesium silicate layers are displaced by b/3 (about 3 Å) resulting in the Si atoms of one siloxane sheet being located above the center of the six-member ring across the interlayer. The water molecules are located 1.2 Å above the center of all six-member rings and accept H-bonds from the OH groups located below the rings. The b/3-displaced structure does not readily transform to either the talc-like or phlogopite-like structure, because neither of these stackings can accommodate two water molecules per formula unit. There is likely to be a compositional discontinuity and phase transition between the b/3-displaced phase and the phase with phlogopite-like stacking. The simulations reported here are the first to use the recently developed CLAYFF force field to calculate mineral structures at elevated pressures and temperatures.  相似文献   

The Present Space-Time Motion and Deformation Features of the Northeastern Margin of the Qinghai-Xizang（Tibet） Block and Its Adjacent Area     

Zhang Xiaoliang 《中国地震研究》2004,18(2):161-170

On the basis of Discontinuous Deformation Analysis (DDA), and considering the moderate intrusion of specific block boundaries to different extents, the first-order block motion model is established for the northeastern margin of Qinghai-Xizang(Tibet) block and the kinematical model for depicting deformation of small regions as well by using GPS observations of three periods (1991, 1999 and 2001). By simulating, we obtained the motion features of the firstorder blocks between the large WWN faults on the sides of the studied region, the distribution features of the principal strain rate field and the inhomogeneous motion features with spacetime of the faults in the northern boundary of the Qinghai-Xizang (Tibet) block.  相似文献   

Palaeozoic deformation and magmatism in the northern area of the Anatolide block (Konya), witness of the Palaeotethys active margin   总被引：1，自引：0，他引：1  

Ya ar Eren  Hüseyin Kurt  François Rosselet  Gérard M. Stampfli 《Eclogae Geologicae Helvetiae》2004,97(2):293-306

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机载POS系统对地定位方法初探   总被引：16，自引：4，他引：16  

郭大海  吴立新  王建超  郑雄伟 《国土资源遥感》2004,15(2):26-31

高精度定位定向系统(Position&;OrientationSystem,简称POS系统)能够获取机载传感器的空间位置和三轴姿态信息,从而定量化反演遥感信息获取过程,实现机载遥感直接对地定位(DirectGeoreferencing)。本文首先介绍POS与航空摄影系统的集成方法与工作原理;然后初步分析了POS系统的主要误差来源,在此基础上,研究了POS系统数据处理及误差控制方法;最后,结合河南安阳飞行试验数据的分析处理结果,进行了精度和可行性分析。  相似文献   

无地面控制GPS辅助光束法区域网平差   总被引：2，自引：4，他引：2  

袁修孝  朱武  武军郦  王瑞幺 《武汉大学学报(信息科学版)》2004,29(10):852-857

介绍了在WGS-84坐标系中进行GPS辅助光束法区域网平差的基本原理以及利用大地水准面拟合方法实施大地高与正常高的变换方法。利用新疆库尔勒地区1：25000和1：50000实际航摄资料验证了理论与程序实现的正确性。试验结果表明，无地面控制GPS辅助光束法区域网平差可用于中小比例尺测图的加密，在WGS-84坐标系中可以获得较高的点定位精度，而在国家80坐标系下，利用大地水；隹面拟合前后的GPS摄站坐标进行GPS辅助光束法区域网平差，加密精度没有明显差异。  相似文献   

Magnetic quantification of urban pollution sources in atmospheric particulate matter   总被引：9，自引：0，他引：9  

S. Spassov  R. Egli  F. Heller  D. K. Nourgaliev  J. Hannam 《Geophysical Journal International》2004,159(2):555-564

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