Layer parallel shortening in salt-detached folds: constraint on cross-section restoration     

M. Sans  J. Vergs  E. Gomis  J. M. Pars  M. Schiattarella  A. Trav  F. Calvet  P. Santanach  A. Doulcet 《Tectonophysics》2003,372(1-2):85-104

Cleavage-fissility perpendicular to bedding is a common feature in the external part of fold-and-thrust belts. Three techniques were used to determine the internal distortion in the frontal Southern Pyrenees: the analysis of strain markers such as burrows and rain drops, the measurement of fissility, and the measurement of anisotropy of magnetic susceptibility (AMS). The comparison of the three techniques showed a good fit although they differ in sensitivity to penetrative strain variations in the range of deformation values explored in the study case. On the regional scale, the values of layer parallel shortening (LPS) derived from the markers analysis are very constant and account for 16–23% of shortening. These values are two to three times larger than the shortening values calculated from the restoration of the macroscopic scale structures and indicate a good decoupling above the Cardona salt Formation. This study permitted an accurate restoration of the low-amplitude el Guix detached anticline.  相似文献   

动力刚度计算方法-"盐溶”法-的改进   总被引：1，自引：0，他引：1  

丁海平  廖振鹏 《地震工程与工程振动》2001,21(2):13-18

本文首先讨论了采用盐溶法（damping-solvent extraction method)争动力刚度时，在某些频率点（奇点）产生误差的原因；提出一种多次逼近的改进办法，提高了计算精度。在一般情况下，动力刚度的奇点是未知的。本文建议的逼近技术可用于校核这一方法所获得的结果。  相似文献   

Robustness analysis of geodetic horizontal networks   总被引：2，自引：1，他引：2  

P. Vaníček  M. R. Craymer  E. J. Krakiwsky 《Journal of Geodesy》2001,75(4):199-209

  相似文献   

单轴压缩下大理岩的Q值与频率关系的研究          下载免费PDF全文

马丽云  赵建华 《地球物理学报》1990,33(6):689-693

实验采用单轴压缩循环加载方式,在地震频段内测量了莱阳大理岩的品质因数Q值.在频率为0.1-10 Hz范围内,Q值随频率变化是非线性的,而且在5 Hz附近出现峰值.用正弦波和用三角波两种方式加载所获得的Q值与频率关系很相似,并且三角波加载所测得的Q值普遍高于用正弦波加载测得的Q值.疲劳试验结果表明,正弦波循环加载大大降低了岩石的强度,三角波则对岩石强度降低较少.  相似文献   

Seismic risk of circum-pacific earthquakes I. Strain energy release   总被引：1，自引：0，他引：1  

Kostas C. Makropoulos  Paul W. Burton 《Pure and Applied Geophysics》1983,121(2):247-267

Commonly used earthquake “whole process” frequency - magnitude and strain energy - magnitude laws are merged to obtain an analytic expression for an upper bound magnitude to regional earthquake occurrenceM ₃, which is expressed primarily in terms of the annual maximum magnitudeM ₁ and the magnitude equivalent of the annual average total strain energy releaseM ₂. Values ofM ₃ are also estimated graphically from cumulative strain energy release diagrams. Both methods are illustrated by application to the high seismicity of the circum-Pacific belt, using Duda’s (1965) data and regionalisation. Values ofM ₃ obtained analytically, with their uncertainties, are in agreement with those obtained graphically. Empirical relations are then obtained betweenM ₁,M ₂, andM ₃, which could be of general assistance in regional seismic risk considerations if they are found to be of a universal nature. For instance.M ₃ andM ₂ differ by one magnitude unit in subregions of the circum-Pacific.  相似文献   

Large-strain deformation and strain partitioning in polyphase rocks: Dislocation creep of olivine–magnesiowüstite aggregates     

Misha Bystricky  Florian Heidelbach  Steve Mackwell   《Tectonophysics》2006,427(1-4):115

Aggregates composed of olivine and magnesiowüstite have been deformed to large strains at high pressure and temperature to investigate stress and strain partitioning, phase segregation and possible localization of deformation in a polyphase material. Samples with 20 vol.% of natural olivine and 80 vol.% of (Mg_0.7Fe_0.3)O were synthesized and deformed in a gas-medium torsion apparatus at temperatures of 1127 °C and 1250 °C, a confining pressure of 300 MPa and constant angular displacement rates equivalent to constant shear strain rates of 1–3.3 × 10^− 4 s^− 1. The samples deformed homogeneously to total shear strains of up to γ  15. During constant strain rate measurements the flow stress remained approximately stable at 1250 °C while it progressively decreased after the initial yield stress at the lower temperature. Mechanical data, microstructures and textures indicate that both phases were deforming in the dislocation creep regime. The weaker component, magnesiowüstite, controlled the rheological behavior of the bulk material and accommodated most of the strain. Deformation and dynamic recrystallization lead to grain refinement and to textures that were not previously observed in pure magnesiowüstite and may have developed due to the presence of the second phase. At 1127 °C, olivine grains behaved as semi-rigid inclusions rotating in a viscous matrix. At 1250 °C, some olivine grains remained largely undeformed while deformation and recrystallization of other grains oriented for a-slip on (010) resulted in a weak foliation and a texture typical for pure dry olivine aggregates. Both a-slip and c-slip on (010) were activated in olivine even though the nominal stresses were up to 2 orders of magnitude lower than those needed to activate these slip systems in pure olivine at the same conditions.  相似文献   

基于Monte Carlo方法的由GPS观测计算地应变率的误差分析   总被引：3，自引：1，他引：3       下载免费PDF全文

朱守彪  石耀霖 《地球物理学报》2007,50(3):806-811

在利用GPS观测计算地应变率中，应变率的误差分布在地球动力学研究中非常重要. 为解决这一问题，文中提出基于Monte Carlo技术，利用GPS观测的速度计算地应变率进行误差分析的方法；以青藏高原地区为例，利用带有误差的GPS观测数据进行了大量、独立的应变率重复计算，然后运用统计方法给出了应变率分量及其误差的分布. 结果显示青藏高原的喜马拉雅及中东部地区地应变率的东西向、南北向及剪应变率分量的误差相对较大，但整个青藏高原及附近地区应变率结果稳定可靠；研究结果进一步表明，由GPS观测计算应变率的误差主要决定于GPS观测速度的误差， 在变形小的区域（如中国东部地区），目前GPS的观测精度还不能完全满足地应变率计算的要求.  相似文献   

任意色阶区间精细选区创建方法初探     

江王记 《现代测绘》2007,30(6):37-38

在通道中利用“阂值”命令创建选择X-255。在通道混合中创建任意色阶区间选择X1～X2。利用通道混合“减去”模式中“缩放”“补偿值”实现深度自由选择。  相似文献   

3-D shell analysis of cylindrical underground structures under seismic shear (S) wave action   总被引：1，自引：1，他引：1  

George P. Kouretzis  George D. Bouckovalas  Charis J. Gantes 《Soil Dynamics and Earthquake Engineering》2006,26(10):909-921

The 3-D shell theory is employed in order to provide a new perspective to earthquake-induced strains in long cylindrical underground structures, when soil-structure interaction can be ignored. In this way, it is possible to derive analytical expressions for the distribution along the cross-section of axial, hoop and shear strains and also proceed to their consistent superposition in order to obtain the corresponding principal and von Mises strains. The resulting analytical solutions are verified against the results of 3-D dynamic FEM analyses. Seismic design strains are consequently established after optimization of the analytical solutions against the random angles which define the direction of wave propagation relative to the longitudinal structure axis, the direction of particle motion and the location on the structure cross-section. The basic approach is demonstrated herein for harmonic shear (S) waves with plane front, propagating in a homogeneous half-space or in a two layer profile, where soft soil overlays the bedrock.  相似文献   

Inversion of coseismic stress-triggered fault slips using borehole strainmeter observations     

邱泽华  阚宝祥唐磊  张超凡宋茉 《地震学报(英文版)》2006,19(6):643-649

Coseismic stress-triggering is becoming a new hot spot of research. Coseismic strain steps recorded by borehole strainmeters are particularly valuable in studying coseismic stress-triggered fault slips. Based on the theory of dis location, one can invert the triggered fault slips with such data if he/she has a well understanding about the local faults. Genetic algorithm can be applied to significantly raise the efficiency of searching a best solution among all possibilities in this kind of inversion. A testifying check of the program and analyses of each parameter＇s influence may further enhance the reliability of inversion results. Taking complexity of geological structure into account, the inversion results should be regarded as the predominant property or a comprehensive effect of triggered local faults＇ activities. As an attempt, we inverted the assumingly active faults＇ slips triggered by the Ms=8.1 Kunlun Mountain earthquake over Beijing area.  相似文献