1966年以来华北地区一系列七级大震破裂过程的数值模拟   总被引：9，自引：5，他引：9       下载免费PDF全文

陈祖安  白武明  林邦慧  王新华  许国凯  张瑞清  黄为清 《地球物理学报》2003,46(3):373-381

用非连续变形分析方法(DDA+FEM)数值模拟，在华北地区各地块相互制约的块体系统环境中，地块边界断层上发生1966年邢台地震、 1969年渤海地震、 1975年海城地震、 1976年唐山地震等不同类型破裂模式大震的破裂过程. 数值模拟结果给出每个大震释放的主应力场，最大剪应力变化等值线图，地震前后位移变化矢量图，发震断层滑移随时间变化以及走滑错距和应力降等震源参数. 这些结果与地震的震源机制，用地震波资料研究得到的震源参数,宏观等震线,地表观测的水平位移矢量图基本一致. 其中1969年渤海地震正交破裂模式的结果与宏观等震线及小震分布图像更接近. 1976年唐山地震复杂震源模式与该震早期余震分布图像更相符. 表明用DDA+FEM方法进行数值模拟研究，能较好地模拟地震破裂过程.  相似文献   

中国大陆及其邻区强震活动与活动地块关系研究   总被引：16，自引：0，他引：16  

马宏生  张国民  刘杰  李丽  陈化然 《地学前缘》2003,10(Z1):74-80

从活动地块假说出发 ,在活动地块研究的基础上 ,探讨了中国大陆及邻区活动地块与强震活动的关系。研究指出 ,主要构造变形和强烈地震大都发生在活动地块边界。在占总面积 17%的活动地块边界上 ,集中了全部的 8级以上巨大地震和 86 %的 7级以上大地震 ,其释放能量占全部总能量的 95 %以上 ,表明中国大陆及其邻区活动地块边界带控制了绝大部分的强地震。从活动地块的整体来看 ,强震活动不仅显示出显著的韵律性特征 ,而且其高、低起伏基本上与中国大陆地区一致 ,只是强震活跃时段有时稍长于中国大陆。各轮回强震活动都有各自活动的主体地区 ,反映了不同活跃期内地块的不同活动方式。文中还从现今地壳运动角度 ,讨论了活动地块运动速率与强地震活动水平之间的可能联系。  相似文献   

地球物理学及大地构造学中关于地壳均衡的新模型(英文)     

Tyap.  KF 《地学前缘》2000,7(1):69-78

讨论了一些有关地壳均衡概念的模型。业已证明 ,这些模型既不能用以正确评估地球的平衡状态 ,也不能用以解释构造成因。介绍一种新的地壳均衡模型 ,它与地球的某一种旋转方式相适应。地球体与球的偏差 ,被用来作为地球平衡的判据。地球被认为是在偏差趋近于零的那些点上得到平衡的。地球体与球体之间标志的差异 ,是由地球外壳中地质作用的方向所确定的。所提出的是大地地壳均衡模型 ,是地壳中构造形成新旋转假说的基础。  相似文献   

Determining the maximum degree of harmonic coefficients in geopotential models by Monte Carlo methods   总被引：1，自引：0，他引：1  

K. R. Koch r 《Studia Geophysica et Geodaetica》2005,49(3):259-275

Random errors for the harmonic coefficients of a geopotential model are generated from the matrix of normal equations by a parallel computer applying the Gibbs sampler. This leads to random values for the harmonic coefficients. They are transformed by nonlinear, quadratic transformations to random values for the square roots of degree variances, of mean squares of geoid undulations and gravity anomalies. The expected values of these quantities are not equal to the values of these quantities computed by the estimated harmonic coefficients, due to correlations and errors in the estimation. By hypothesis tests estimated harmonic coefficients distorted by correlations and errors are detected. Applying the tests to the geopotential model ITG-CHAMP01 of the Institute of Theoretical Geodesy in Bonn it is concluded that above the degree 62 the harmonic coefficients cannot add any information to the geopotential model.  相似文献   

Efficiency of kriging estimation for square, triangular, and hexagonal grids   总被引：8，自引：0，他引：8  

Evangelos A. Yfantis  George T. Flatman  Joseph V. Behar 《Mathematical Geology》1987,19(3):183-205

Although several researchers have pointed out some advantages and disadvantages of various soil sampling designs in the presence of spatial autocorrelation, a more detailed study is presented herein which examines the geometrical relationship of three sampling designs, namely the square, the equilateral triangle, and the regular hexagon. Both advantages and disadvantages exist in the use of these designs with respect to estimation of the semivariogram and their effect on the mean square error or variance of error. This research could be used to design optimal sampling strategies; it is based on the theory of regionalized variables, in which the intrinsic hypothesis is satisfied. Among alternative designs, an equilateral triangle design gives the most reliable estimate of the semivariogram. It also gives the minimum maximum mean square error of point estimation of the concentration over the other two designs for the same number of measurements when the nugget effect is small relative to the variance. If the nugget effect is large (.90 ² or more), and the linear sampling density is >0.85r where r is the range, the hexagonal design is best. This study computes and compares the maximum mean square error for each of these designs.  相似文献   

编制地壳垂直运动速率等值线图的有限元法   总被引：2，自引：0，他引：2  

李家权  张勤 《大地测量与地球动力学》1998,(3)

根据地壳垂直运动研究中的均衡理论,建立描述地壳垂直运动速率空间分布的数学模型,并提出应用有限元法拟合地壳垂直运动速率面的理论和方法。通过计算验证,说明有限元法可实现对地壳垂直运动速率面的精确逼近,是编制地壳垂直运动速率等值图的有效方法。  相似文献   

公转轴应力场星球说——地球、火星南南西应力场四组三维构造系     

孙兆元  孙娟 《地球科学进展》1999,14(3):218-228

介绍了对地球构造格局,运动方式及其动力源问题研究取得的新成果。它不同于流行已久的以地球自转轴旋转和以软流圈带动岩石圈漂移以及随机的地幔柱（流）为构造动力源的观点,而是与黄赤交角相关的沿公转轴方向的统一应力场,认为中国西部ＮＷＷ向压性,ＮＥＥ与ＮＮＷ是与黄赤交角相关的沿公转轴方向的统一应力场。认为中国西部ＮＷＷ向压性,ＮＥＥ与ＮＮＷ向两组共轭扭性及ＮＮＥ向张性带交接,为来自全球ＳＳＷ主压应力场形成的  相似文献   

精密重力网的定权及系统效应     

杨重谊 《武汉大学学报(信息科学版)》1990,(4)

对于精密重力网,如何确定各类观测值的权,如何剔除相对重力仪过多的参数,是目前尚未解决好的两个问题。本文讨论了利用方差分量估计确定各类观测值的权,利用几种假设检验选择附加参数的方法以及相关的几个问题。经过计算和比较分析,得到了较好的结果。  相似文献   

Image resolution and evaluation of genetic hypotheses for planetary landscapes     

James R. Zimbelman 《Geomorphology》2001,37(3-4)

The spatial resolution of image data tends to constrain the horizontal length scale of genetic hypotheses that are addressable by those data. No ‘simple’ formula exists when image resolution is sufficient to test a given geomorphic process, which is dependent on what characteristics are diagnostic of the particular process. Genetic hypotheses should be formulated along the lines of the “multiple working hypotheses” concept as described in a classic paper by Chamberlin [J. Geol. 5 (1897) 837]. An essential element of a viable working hypothesis is a clear indication of the characteristics predicted by, or a consequence of, the hypothesis. An untestable hypothesis is not an effective working hypothesis. The history of the study of lunar sinuous rilles is outlined as an illustration of the influence of image resolution and the formulation of genetic hypotheses on the subsequent advancement of understanding of the problem. Sinuous rilles on Venus and Mars, and controversial sinuous ridges on Mars are also reviewed. In the lunar case, the three-order-of-magnitude improvement in spatial resolution provided by Lunar Orbiter photographs over Earth-based telescopic photographs did not result in definitive examination and elimination of published hypotheses for the formation of sinuous rilles. Topographic data obtained from cartographically controlled Apollo orbital photographs, along with important observations and samples obtained by the astronauts on the lunar surface, did test and exclude several hypotheses. The formulation of a genetic hypothesis, including testable consequences of that hypothesis, is a greater determinant of its ultimate utility to the scientific community than is the image resolution available at any given time.  相似文献   

形变反演模型的非线性平差   总被引：1，自引：0，他引：1  

陶本藻 《武汉大学学报(信息科学版)》2001,26(6):504-508

阐述了反演问题参数估计的质量要求，将反演理论中的分辨率和精度与平差中的良好统计性质作了对比分析，为使反演参数得到良好估计，提出平差处理对策。针对反演问题经常是非线性模型，提出了非线性平差的几种方法，最后给出参数筛选的原则和相应的统计检验方法。  相似文献