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建立了基于有限断层的芦山地震的混合震源模型,突出破裂面上滑动量分布中凹凸体的主导作用,同时借助k平方模型表达对震源复杂性认识尚不够深入所带来的随机性.混合震源模型中全局震源参数均值与局部震源参数均值的确定,主要依据统计的半经验标定公式,进一步借助截断正态分布将区域地震、地质构造、地震活动性提供的参数限值结合起来,生成最终的震源参数值.基于上述思路,本文共建立了30组芦山地震混合震源模型,进而以芦山地震8个近场观测台站为试算点,借助地震动反应谱残差评价的方法,从30组模型中选定了表达“平均”特征的混合震源模型. 相似文献
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三维破裂及其在地震和断层研究中的应用（综述） 总被引：5，自引：0，他引：5
文中提出若干断层破裂和震源过程的重要问题,包括断层分布的形态、震源多重事件的非共面性、震源迁移和动力来源等,这些问题用目前二维力学模型无法回答,只有用三维模型才有可能。综述了三维岩石断裂力学的实验和Ｇｒｉｆｉｔｈ－Ｉｒｗｉｎ理论研究的进展情况,指出三维破裂研究既包括三维裂纹的破裂,也包括无初始裂纹的Ｈｅｒｔｚ接触引起的破裂。总结了岩石三维破裂的特征,并简述了三维破裂在震源过程和断层形成问题研究中的一些证据和研究前景,认为一些地震前兆机理问题有可能在三维模型中得到解答。同时也讨论了三维震源与断层模型简化为常用的二维模型的条件。 相似文献
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本文在考虑环境刚度效应和非匀阻效应的情况下,采用椭圆形震源简化模型,研究了走滑断层的地震烈度几何要素与震源参数之间的关系,初步建立了估计断层有效发震段长度、错动角、应力降和错动距离等参数的等震线法,并结合唐山、通海、炉霍和永善等震例进行了试算 相似文献
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基于有限断层震源、且使用动力学拐角频率的地震动随机模拟方法预测玉树地震近断层的加速度场.首先,基于有限断层震源建模方法建立该次地震的震源模型;然后,基于上述地震动模拟方法预测玉树地震近断层191个节点的加速度时程.在此基础上,取每个结点的加速度峰值绘制该次地震的近断层加速度场.结果表明:(1)近断层加速度场主要受震源破裂过程和断层面上滑动分布的影响.断层面上凹凸体投影到地表的区域附近,加速度峰值最大,也是震害最严重的区域;(2)对于走滑地震,断层沿线附近的场地并非均会发生破裂方向性效应;发生破裂方向性效应的场地与凹凸体在断层面上的位置有关. 相似文献
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川滇地区是我国地震危险性较高的地区之一.本文基于对特大强震的风险性考虑,使用全球地震模型OpenQuake软件,建立了川滇地区地震危险性预测新模型.首先根据构造特征划分多个震源分区,并整理出这些震源分区内断层活动特征与滑动速率;基于震源分区和断层模型,使用GPS应变率转换成的锥形古登堡-里克特关系作为整个区域的地震积累率,并允许超过历史最大震级的特大地震的出现,结合活动断层滑动速率所积累的地震发生率,给出震源分区内断层地震源和背景地震源的地震发生率的比率分配关系;在活动断层分段上,保留了大型断裂或其主要部分,没有根据小的阶区来对断层进行详细分段,以便分配特大地震发生率;并使用地震率平滑方法分配背景地震发生率.最后在OpenQuake中加入地震动预测方程,计算出了川滇地区的PGA分布图,为区域地震危险性提供科学依据. 相似文献
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震后近断层震动图的快速产出对于政府相关部门快速确定地震影响区、评估震害及其导致的经济损失和人员伤亡、科学决策应急救援方案和措施以减轻人员伤亡和财产损失具有重要意义。以2022年门源地震为例,利用滑动分布、应力降均不同的两个震源模型（即,王卫民等反演的震源模型和本研究生成的随机滑动震源模型）以及相同的路径、场地模型和其它输入参数,使用动力学拐角频率的随机有限断层方法和本研究建立的峰值地面速度（PGV）、水平向最大谱烈度（SI）和中国仪器地震烈度（II）的经验模型研究了快速产出近断层震动图（包括峰值地面加速度图、PGV图、SI图、II图和中国地震烈度图）的实效性。结果表明:（1）上述方法和经验模型可用于震后震动图的快速产出,其实效性主要取决于震源、路径和场地模型的可靠性;（2）基于上述两种震源模型产出的地震烈度图与中国地震局发布的该次地震的烈度图在总体上具有高度一致性,均可用于确定地震影响区,但基于反演震源模型产出的地震烈度图可以给出极震区,而基于随机滑动震源模型产出的地震烈度图则需要根据其最大等震线和发震断层的位置大致估计极震区的位置。 相似文献
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基于震源机制解的断层三维动画自动生成系统以地震应急实际需求为导向,根据震源机制解提供的断层走向、倾角和滑动角,通过对断层模型进行三维建模,建立断层控制点的运动方程,利用动画自动生成技术,生成发震断层的三维演示动画。利用该系统制作了九寨沟7.0级、精河6.6级地震的三维运动动画。该系统自动产出的断层三维动画,可在地震应急期间为抗震救灾指挥部展示直观的断层运动过程,并且结合余震分布等信息可为震后趋势的判定提供科学依据,同时,可借助微博、微信等新媒体为社会公众提供更好的服务。 相似文献
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断层面上某一点的滑动时间函数需要用三个参数来表达:断层的平均位错量、上升时间和破裂传播的时间延迟。本文基于有限断层模型,根据断层面上每个子源的位错量时、空不均匀分布特征,采用Brune模型系统确定了相应滑动时间函数的三个参数,构建了位错量呈时、空不均匀分布的有限断层滑动模型。该方法可以表现破裂面上断层位错量在时间和空间上分布的不均匀特征,既能够表现震源的复杂性同时又能够简化震源模型的构建过程,为考虑断层附近的强地震动数值模拟计算提供了有效的途径。 相似文献
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In this paper, a global inversion method is developed for seismic moment tensor inversion by using the body wave forms. The
algorithm depends on neither the selection of starting model nor the forms of objective function and constraints. When the
error function, measure of the difference between the observed and synthetic waveforms, is chosen as the objective function,
the best fitting source model is found; when a certain combination in seismic moment tensor elements is selected as the objective
function and the values of error function are constrained in a suitable bound, the extreme source models can be produced by
minimizing or maximizing this combination. By changing the form of the combination of moment tensor elements, a variety of
different source characteristics can be considered. Therefore the extreme solution provides an estimation of the uncertainty
in the best fitting source model. The seismic waveform data was used to evaluate the effectiveness of this algorithm.
This research was supported by the National Natural Science Foundation of China. 相似文献
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Three-dimensional displacements and gravity changes were measured at 20 points between 2000 and 2002 at Merapi volcano, Java,
Indonesia. Former models focused on the modeling of a single magmatic source located in the summit region of the volcano.
Such models do not fit to our measurements between 2000 and 2002. A new hybrid model approach is developed consisting of an
elastic-gravitational source described by a mass and energy term as well as a combined dip-slip/strike-slip fault zone in
the summit region. Both nonlinear optimization problems, given by the common inversion of three-dimensional displacements
and gravity changes, are solved by applying a genetic algorithm. The hybrid model fits the measurements accurately, tested
by Fisher test statistics. Furthermore, our model for Merapi volcano confirms previous structural models for this region so
that the new model is statistically proven as well as physically reliable. 相似文献
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本文利用2015年尼泊尔MW7.9地震断层面滑动位移分布的运动学反演结果,通过傅里叶变换法得到了主断层面上的两分量应力状态,并研究了余震的空间分布和断层面上应力状态之间的关系.发现滑动位移分布与应力状态分布都相对较为集中,大约70%的余震分布在应力变化为正的区域,而其余发生在应力降区域的余震,又大多发生在应力变化梯度较大的地区.为了得到一个更符合实际的滑动模型来解释余震的触发机制,我们计算了波数域中滑动位移和应力状态的傅里叶谱,发现此次地震的滑动位移和应力状态近似满足k-3和k-2衰减.我们利用简化的圆盘模型说明了非均匀应力变化下的衰减过程,计算了圆盘模型的有效半径re约等于0.7倍的圆盘半径.这就说明圆盘模型中应力增加的部分应该占整个圆盘破裂面积的51%.在本次尼泊尔MW7.9地震实例中,断层面上应力状态为负的区域比滑动位移为正的区域有了明显地缩小.事实表明,余震可以发生在有滑动位移的区域,非均匀应力降模型比均匀应力降模型更加接近真实的震源破裂过程. 相似文献
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《国际泥沙研究》2019,34(6):577-590
Bayesian and discriminant function analysis (DFA) models have recently been used as tools to estimate sediment source contributions. Unlike existing multivariate mixing models, the accuracy of these two models remains unclear. In the current study, four well-distinguished source samples were used to create artificial mixtures to test the performance of Bayesian and DFA models. These models were tested against the Walling-Collins model, a credible model used in estimation of sediment source contributions estimation, as a reference. The artificial mixtures were divided into five groups, with each group consisting of five samples with known source percentages. The relative contributions of the sediment sources to the individual and grouped samples were calculated using each of the models. The mean absolute error (MAE) and standard error of (SE) MAE were used to test the accuracy of each model and the robustness of the optimized solutions. For the individual sediment samples, the calculated source contributions obtained with the Bayesian (MAE = 7.4%, SE = 0.6%) and Walling-Collins (MAE = 7.5%, SE = 0.7%) models produced results which were closest to the actual percentages of the source contributions to the sediment mixtures. The DFA model produced the worst estimates (MAE = 18.4%, SE = 1.4%). For the grouped sediment samples, the Walling-Collins model (MAE = 5.4%) was the best predictor, closely followed by the Bayesian model (MAE = 5.9%). The results obtained with the DFA model were similar to the values for the individual sediment samples, with the accuracy of the source contribution value being the poorest obtained with any of the models (MAE = 18.5%). An increase in sample size improved the accuracies of the Walling-Collins and Bayesian models, but the DFA model produced similarly inaccurate results for both the individual and grouped sediment samples. Generally, the accuracy of the Walling-Collins and Bayesian models was similar (p > 0.01), while there were significant differences (p < 0.01) between the DFA model and the other models. This study demonstrated that the Bayesian model could provide a credible estimation of sediment source contributions and has great practical potential, while the accuracy of the DFA model still requires considerable improvement. 相似文献
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Tauhidur Rahman 《地震科学（英文版）》2012,25(4):323-338
A point source seismological model is used in this study to model the available strong motion accelerograms recorded by 17 events and to calculate three seismological model parameters, the source, path, and quality factor. Due to the paucity of recorded events, this is the first time these model parameters have been obtained for the northeastern and its surrounding region of India. The quality factors of the horizontal and vertical components of recorded events with corresponding standard deviations are QH(f) = 188.55f0.94, σ1 value (25, 0.025) and QV(f) = 169.76f0.93, σ1 value (20, 0.03), respectively. The source parameter stress drop values (μσ) vary within 124–180 bars for the subduction region and 80–169 bars for the active region. The Kappa factors for the horizontal and vertical components of recorded events on the soft rock site are 0.06 and 0.05, respectively. These seismological model parameters obtained in this study will be useful for future work deriving a ground motion attenuation relation based on a spectral model. Finally, these results are useful for seismic hazard assessment of a region having sparsely recorded events. 相似文献
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An earthquake is regarded as a fracture from the viewpoint of continuum mechanics, in which stress and strain play key roles in understanding the nature of a seismic source. This review briefly outlines the mechanics of a seismic source in terms of the dislocation model and crack model. The introduction includes the Coulomb failure criterion, static stress drop, dynamic stress drop, the Griffith criterion, and the scaling of source parameters. The selection of topics in the introduction emphasizes the application of seismic data, i.e., in practice, the mechanical parameters introduced here are measurable in the interpretation and analysis of seismic waveform data. 相似文献
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基于“2015模型”和分区模型对比的方法，开展折合走时、典型地震、爆破和塌陷以及PTD震源深度测定4个方面的模型适用性检验。检验结果显示，采用分区模型时，随机抽取事件均位于折合走时理论线中间；典型事件、爆破和塌陷使用分区模型得到的定位残差较“2015模型”明显减小，且使用“3个区域与编目”获得的震中差较“2015—编目”有明显降低。使用分区模型进行PTD震源深度测定，更符合内蒙古分区地壳厚度分布特征。分区模型与全球地壳模型crust 1.0、crust 2.0和使用接收函数得到的Moho面厚度分布结果基本一致。综合认为，内蒙古西部、中部、东部一维地壳速度模型更符合内蒙古地区区域地质构造特征。 相似文献
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Tomoyuki Takahashi Takeyuki Takahashi Nobuo Shuto Fumihiko Imamura Modesto Ortiz 《Pure and Applied Geophysics》1995,144(3-4):747-767
A source model for the 1993 Hokkaido Nansei-Oki tsunami must satisfy certain conditions. Such conditions are presented in this paper, and two methods are used to determine the best source model for this event. A trial-and-error method selects DCRC-17a as the best among 24 different models. This model has three fault planes dipping westward. To reproduce well the tide gauge records at two locations, an inversion analysis is used to modify the dislocation of DCRC-17a. 相似文献
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磁场模式是表述空间磁场的一种有效工具,对于研究磁层大尺度电流系的发展变化和辐射带粒子具有重要意义.本文介绍了三种主要的磁层磁场模式,即经验模式、抛物面模式和事件导向模式,结合模式的原理和特点,对模式的改进情况和性能检验进行了详细论述,并对三种模式进行了对比分析.三种模式都能对暴时磁场进行动态模拟.最近的Tsyganenko模式考虑了太阳风的历史作用,每个磁场源都有自己的松弛时间尺度及驱动函数;抛物面模式A01中增加了场向电流及窄尾流效应;事件导向模式G03增加了非对称环电流和局地窄尾流片效应. 相似文献
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We propose a mathematical representation to qualitatively describe the spatio-temporal slip evolution during earthquake rupture
in an efficient and easy-to-use manner for numerical simulations of strong ground motion. It is based on three basis functions
and associated expansion coefficients. It is an extension of the approach of Ide and Takeo, (J Geophys Res, 102:27379–27391, 1997). We compare our approach and theirs using simple kinematic source models to illustrate differences
between the two approaches, and show that our approach more accurately represents the spatio-temporal slip evolution. We also
propose a technique based on our representation for extracting a spatio-temporal slip velocity function from a kinematic source
model obtained by the conventional source inversion. We then demonstrate the feasibility of our procedure with application
to an inverted source model of the 26 March 1997 Northwestern Kagoshima, Japan, earthquake (M
W6.1). In the simulations for actual earthquakes, source models obtained from kinematic source inversions are commonly employed.
Our scheme could be used as an interpolation method of slip time functions from relatively coarse finite-source models obtained
by conventional kinematic source inversions. 相似文献