Nucleation of earthquakes and its implication to precursors   总被引：1，自引：0，他引：1  

李世愚  滕春凯  卢振业  刘晓红  刘绮亮  和雪松 《地震学报(英文版)》2000,13(2):224-233

IntroductionIn the middle of 1990s, the argument about nucleation phase occurred. Ellsworth and Beroza(1 995) studied the wave records of 30 earthquake events, which initiated slowly. Ellsworth, et al calledthem as nucleation phase. They discussed the relationship between their moment, duration time andthe relationship with the main shock behind. Scherbaum (1997a, b) proposed his different view andsuggested that some of the recording of the long period initial of seismic wave was misinterpret…  相似文献   

1997年伽师强震群活动的近场定点形变异常特征   总被引：3，自引：0，他引：3  

温和平 《华南地震》2000,20(2):40-46

对１９９７年伽师强震群前后的近场宁点形变资料和卡尔曼滤波结果的前兆异常进行了分析,结果表明,震前短临异常较为明显。通过密切跟踪,在后续强震的预报中发挥了重要作用。文中还对异常与孕震构造和应力场的关系进行了讨论。  相似文献   

地震安全性评价和高层建筑的地震动输入   总被引：4，自引：1，他引：3  

杨柏坡  窦立军 《地震工程与工程振动》2000,20(1):35-41

本文根据现行的中国地震烈度区划图中烈度的含义,指出在使用现行“建筑抗震设计规范”时存在的一些问题和与《中华人民共和国防震减灾法》的不协调之处。根据多年参加工程场地地震安全性评价的经验,总结了目前进行地震安全性评价过程中存在的一些问题。文中建议：针对高层建筑进行新的场地分类方法的研究;对高层建筑工程场地作地震安全性评价时,可根据高度的不同,适当简化安全性评价过程。  相似文献   

Straightforward methods to detect non-linear response of the soil. Application to the recordings of the Kobe earthquake (Japan, 1995)     

C. Lacave-Lachet  P.Y. Bard  J.C. Gariel  K. Irikura 《Journal of Seismology》2000,4(2):161-173

Simple straightforward methods are applied to testtheir ability to detect the non-linear response of thesoil. Recordings of the main shock and aftershocks ofthe 1995, Hyogo-ken Nanbu (Kobe) earthquake are used.Non-linear effects are investigated using twodifferent techniques, on a collection of data for 12sites situated on different geological structures inthe Kobe and Osaka areas. The first method used is theso-called receiver functions technique (Langston,1979), which consists of computing the spectral ratiobetween horizontal and vertical components of motion.This ratio has been shown to reveal the fundamentalfrequency of a site (Lachet and Bard, 1994; Lachet etal., 1996; Theodulidis et al., 1995, 1996). For eachsite, recordings of the main shock and a set ofaftershocks are considered. The variation of thisspectral ratio for different values of the maximumacceleration recorded at a site is investigated. Bothvariations of the amplitude of the H/V ratio (due tonon-linear behavior, on the horizontal components inparticular) and of the frequency position of theamplified band-width are observed. The secondtechnique used in this study is related to thevariation of the high frequency content of therecordings during the main-shock and its aftershocks.The high frequency spectral decay of the motion,characterized by parameter, is assumed to berelated mainly to the near-surface attenuation. Itshould then increase with increasing peak velocity, incase of non-linearity. The value of kappa iscalculated for the 12 sites in the Kobe area, fordifferent types of soil conditions, and againdifferent values of peak ground acceleration.Variations of kappa are then related to non-linearbehavior of the soil during the Kobe earthquake.  相似文献   

Modelling peak accelerations from earthquakes   总被引：1，自引：0，他引：1  

Debbie J. Dupuis  Joanna Mills Flemming 《地震工程与结构动力学》2006,35(8):969-987

This paper deals with the prediction of peak horizontal accelerations with emphasis on seismic risk and insurance concerns. Non‐linear mixed effects models are used to analyse well‐known earthquake data and the consequences of mis‐specifying assumptions on the error term are quantified. A robust fit of the usual model, using recently developed robust weighted maximum likelihood estimators, is presented. Outlying data are automatically identified and subsequently investigated. A more appropriate model accounting for the extreme value nature of the responses, is also developed and implemented. The implication on acceleration predictions is demonstrated. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

System identification of a concrete arch dam and calibration of its finite element model     

S. W. Alves  J. F. Hall 《地震工程与结构动力学》2006,35(11):1321-1337

A magnitude 4.3 earthquake occurred near Pacoima Dam on 13 January 2001. An accelerometer array that had been upgraded after the Northridge earthquake recorded the motion with 17 channels on the dam and the dam–foundation interface. Using this data, properties of the first two modes are found from a system identification study. Modal properties are also determined from a forced vibration experiment performed in 2002 and indicate a significantly stiffer system than is estimated from the 2001 earthquake records. The 2001 earthquake, although small, must have induced temporary nonlinearity. This has implications for structural health monitoring. The source of the nonlinear behaviour is believed to be loss of stiffness in the foundation rock. A finite element model of Pacoima Dam is constructed and calibrated to match modal properties determined from the system identification study. A dynamic simulation of the 2001 earthquake response produces computed motions that agree fairly well with the recorded ones. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Influence of long‐period filter cut‐off on elastic spectral displacements     

Sinan Akkar  Julian J. Bommer 《地震工程与结构动力学》2006,35(9):1145-1165

The effect of the long‐period filter cut‐off, T_c, on elastic spectral displacements is investigated using a strong ground‐motion database from Europe and the Middle East. The relation between the filter and oscillator responses is considered to observe the influence of T_c for both analogue and digital records, and the variations with site classification, magnitude, filter order and viscous damping. Robust statistics are derived using the re‐processed European data to generalize the effects of the long‐period filter cut‐off on maximum oscillator deformation demands as a function of these seismological and structural features. Statistics with a 95% confidence interval are derived to suggest usable period ranges for spectral displacement computations as a function of T_c. The results indicate that the maximum period at which spectral displacements can be confidently calculated depend strongly on the site class, magnitude and filter order. The period range where reliable long‐period information can be extracted from digital accelerograms is twice that of analogue records. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Approximate incremental dynamic analysis using the modal pushover analysis procedure   总被引：2，自引：0，他引：2  

Sang Whan Han  Anil K. Chopra 《地震工程与结构动力学》2006,35(15):1853-1873

Incremental dynamic analysis (IDA)—a procedure developed for accurate estimation of seismic demand and capacity of structures—requires non‐linear response history analysis of the structure for an ensemble of ground motions, each scaled to many intensity levels, selected to cover the entire range of structural response—all the way from elastic behaviour to global dynamic instability. Recognizing that IDA of practical structures is computationally extremely demanding, an approximate procedure based on the modal pushover analysis procedure is developed. Presented are the IDA curves and limit state capacities for the SAC‐Los Angeles 3‐, 9‐, and 20‐storey buildings computed by the exact and approximate procedures for an ensemble of 20 ground motions. These results demonstrate that the MPA‐based approximate procedure reduces the computational effort by a factor of 30 (for the 9‐storey building), at the same time providing results to a useful degree of accuracy over the entire range of responses—all the way from elastic behaviour to global dynamic instability—provided a proper hysteretic model is selected for modal SDF systems. The accuracy of the approximate procedure does not deteriorate for 9‐ and 20‐storey buildings, although their dynamics is more complex, involving several ‘modes’ of vibration. For all three buildings, the accuracy of the MPA‐based approximate procedure is also satisfactory for estimating the structural capacities for the limit states of immediate occupancy, collapse prevention, and global dynamic instability. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

青藏高原东缘活动构造   总被引：74，自引：0，他引：74  

周荣军  李勇  Michael A.Ellis  何玉林  王凤林  黎小刚 《矿物岩石》2006,26(2):40-51

青藏高原东缘由岷山断块和龙门山构造带构成。以活动构造地貌学为主线,在解析该地区主干断裂晚第四纪以来活动的地质地貌表现的基础上,对一批断裂运动学和史前强震活动的定量数据进行分析研究,结果表明:在岷山断块中,虎牙断裂的平均左旋滑动速率为1.4 mm/a,垂直滑动速率为0.3 mm/a。岷江断裂的平均垂直滑动速率介于0.37 mm/a~0.53 mm/a之间,左旋位错量与垂直位错量大致相当;在龙门山构造带中,茂汶-汶川断裂、北川-映秀断裂和彭县-灌县断裂的平均垂直滑动速率均在1 mm/a左右,且几条主干断裂的右旋位错量与垂直位错量相当。结合震源机制解结果和GPS测量资料,建立晚新生代以来青藏高原东缘向南东方向逸出的构造变形模式。  相似文献   

巴姆地震变形场和应力场：Ⅱ．用FEPG有限元方法求解   总被引：2，自引：0，他引：2  

罗扬施旭  赵永红 《岩石学报》2006,22(9):2375-2380

本文利用 FEPG 有限元程序对2003年12月的巴姆地震变形场和应力场进行了模拟计算。2003年12月26日,巴姆地区发生6.6级地震。Nakamura、Suzuki 等人利用余震资料和地震破坏程度的分布图分析了余震震中的统计分布形式,得到了此次地震的发震断层是巴姆断层以西大约5km 的 Arg-e-Bam 隐伏断层的结论。凌勇等人从差分干涉雷达(D-InSAR)出发,得到了此次地震的同震干涉条纹和雷达视线方向的位移场,并从雷达干涉的相干图上确定了发震断层的痕迹。他们还利用 Okada 程序模拟计算了此次地震的位移场,模拟计算的结果与 D-InSAR 测量的位移场比较符合。Okada 程序从断层的位错为出发点进行计算,从运动学角度对此次地震变形场和应力场进行研究;本文从动力学的角度出发,研究远场区域边界的应力状态以及断层的物性参数的变化对巴姆地震形变场的影响,将各种计算结果进行对比的同时也和前人的结果相比较。本文计算中采用了凌勇等人的断层参数,即 Arg-e-Bam 隐伏断层为近南北走向,向东倾斜,近直立的倾角,右旋走滑,其(Strike,dip,slip)为(175°,80°,173°)。断层未延伸到地表,自地面以下1km 处往下延伸16km 的宽度,断层长度为20km。对断层的杨氏模量、泊松比、断层附近区域的边界受力大小、两个主应力的比例以及主应力的方向的改变对计算结果的影响做了讨论。最后通过上述几组计算结果建立了一个与前人结果较为符合的巴姆地震参数模型。通过计算,一方面揭示了应力状态和物性参数的影响,另一方面也说明 Arg-e-Bam 隐伏断层是此次地震的发震断层这一结论是可信的。  相似文献