共查询到18条相似文献，搜索用时 140 毫秒
1.
采用动力学震源模型，运用谱元法模拟走滑断层单、双侧破裂模式的地面运动，分析模拟2种模式下地震动的方向性效应和脉冲效应，并对比分析2种模式下断层破裂速度、滑移量与滑移速率的异同。研究结果表明：单、双侧破裂模式下的FN分量PGV均表现出明显的方向性效应，而FP分量的PGV方向性效应不明显，且单侧破裂较双侧破裂的地震动方向性效应强；单侧破裂较双侧破裂更易产生脉冲效应，脉冲效应随断层距的增加而减小，表现为脉冲峰值Vp与脉冲周期Tp的减小；脉冲效应与方向性效应的出现使地震动的低频含量提高，且这种效应也将随断层距的增加而减小；单、双侧破裂模式断层的破裂速度与滑移量无明显差异，而最大滑移速率表现出方向性效应，且单侧破裂较双侧破裂明显。 相似文献
2.
选择台湾集集地震和美国北岭地震的近断层地震动记录作为输入,考察了近断层地震动破裂向前方向性与滑冲效应引起的两种不同速度脉冲运动对单自由度体系和长周期橡胶支座隔震建筑结构抗震性能的影响.反应谱分析表明,破裂向前方向性与滑冲效应对工程结构地震响应的影响是随结构周期变化的.在中短周期段,含破裂向前方向性效应地震动的谱加速度值大于含滑冲效应地震动的谱加速度值;而在长周期段,含滑冲效应地震动的谱加速度大于含破裂向前方向性效应的谱加速度值.并且,与无脉冲地震动作用相比,含破裂向前方向性与滑冲效应脉冲的近断层地震动作用下隔震建筑的地震响应显著增大.滑冲效应引起的速度脉冲使隔震建筑底部的层间变形和楼层剪力明显增大,这意味着滑冲效应脉冲比向前方向性效应脉冲对长周期建筑结构的破坏更具危害性. 相似文献
3.
初步分析了近断层速度脉冲的成因和特点,主要包括方向性效应、滑冲效应和上盘效应,并通过集集地震中27个近断层强震台的脉冲记录分析了断层破裂方向和滑移大小对地面运动峰值速度的影响。采用最小二乘法对速度脉冲的分布范围进行了回归分析,大于50 cm/s的速度脉冲主要聚集在断层距为10 km的近断层区域。对不同区域的三分量平均速度反应谱进行统计分析,表明近断层脉冲型地震动具有较大的特征周期和谱值,其中在垂直于断层走向的水平分量上尤为显著,这与断层剪切位错辐射效应的特征基本相符。针对脉冲型地震造成近断层地质灾害频发的现象,由共振效应分析了速度脉冲对边坡岩体的影响。近断层速度脉冲的研究可能对防震减灾、地震预警、震害评估有一定的参考意义。 相似文献
4.
选取断层距小于200 km的64组强震记录数据,基于小波方法分析汶川地震近断层速度脉冲的地震动特性,并将此次地震中获取到的速度脉冲周期和幅值参数与Chi-Chi 地震和Northridge地震进行了比较,统计分析地震震级、距离对速度脉冲的周期和幅值参数的影响.研究表明:(1)汶川地震近断层速度脉冲具有周期长、幅值小的特点.速度脉冲周期主要分布在6~14 s之间,其中51MZQ台沿平行断层的分量脉冲周期最大为14.2 s,速度脉冲幅值与Chi-Chi 地震和Northridge地震相比明显偏小.(2) 速度脉冲记录出现在沿着地震断层破裂传播的方向上,且与地表断裂的距离都在30 km以内,这些长周期速度脉冲的形成可能主要由破裂传播的向前方向性效应引起.(3)速度脉冲的周期随矩震级呈对数线性增大,且随断层距增大有减小趋势.在矩震级小于Mw7.5时,观测到的地震动脉冲幅值为50~150 cm/s之间,与100 cm/s的典型断层滑动速率非常接近;而震级大于Mw7.5时,断层距10km范围内脉冲的幅值已经超过100 cm/s,个别记录的脉冲幅值甚至达到200 cm/s,远超过前人给出的饱和值,这可能与大的永久形变或该处土层介质条件有关. 相似文献
5.
如何实现速度脉冲参数化并对其参数进行特性分析是一个值得深究的问题。从NGA-West2强震动数据库选取126组近断层脉冲型地震动记录,采用速度脉冲模型,基于最小二乘法拟合得到水平分量的速度脉冲模型特征参数,研究震级、断层距、场地类别对脉冲参数的影响,并对比垂直和平行断层分量脉冲参数的特性差异。结果表明:垂直断层分量的脉冲峰值随震级和断层距的变化速率均快于平行断层分量的相应值,场地条件对脉冲峰值随震级和断层距的变化规律具有较大影响;半脉冲周期与主脉冲周期存在强线性相关性,两者随震级的变化规律存在差异;当震级相同时,基岩场地上的脉冲峰值时刻小于土层场地;对于集集地震来说,较小的形状参数主要分布于靠近破裂断层处,随着断层距的增大,不同分量之间的脉冲形状参数的差异也随之变大。 相似文献
6.
基于2021年云南漾濞MS6.4地震序列的强震动记录,建立了地震动参数预测方程,采用破裂方向性效应拟合方法估计了强震动记录丰富且空间分布均匀的九次地震的震源破裂方向性特征.结果表明:其中的四次地震(1号、4号、8号、9号)表现出破裂方向性效应,且均为不均匀双侧破裂,但优势破裂方向不同(4号和8号为东南向,1号西北向,9号西南向),说明2021年漾濞地震序列的地震破裂较为复杂;由于主震(4号地震)的破裂速度较慢(约为2.2 km/s),其破裂方向性效应较弱且主要对峰值速度有影响,其它三次地震破裂方向性效应十分显著,破裂速度大于主震;此外,四次地震的破裂方向性效应还存在一定的周期相关性. 相似文献
7.
利用中国台湾省内222个强震动台站以及Palert地震预警系统520个台站所观测的三分量加速度记录,研究此次花莲M_W6.4地震近场强地震动空间分布和衰减特征,将观测结果与美国NGA-West2地震动经验预测模型进行对比,揭示此次台湾花莲地震近场地震动的长周期特点,基于回归残差分析研究地震动峰值加速度(PGA)、峰值速度(PGV)和不同周期地震动的空间分布差异,定量考察近场地震动的方向性效应.研究结果表明:(1)整体上此次地震的近场PGV观测值和周期1.0s以上的长周期加速度谱值与美国NGA-West2地震动预测模型结果接近,PGA观测值和周期小于1.0s的加速度反应谱略低于预测模型结果.从空间分布来看,周期1.0s以上的长周期地震动在断层的不同方位有系统性差异,在破裂传播前方(震中西南方位),周期大于1.0s时的反应谱明显高于美国NGA-West2地震动经验预测模型,在破裂传播后方(震中东北方位),周期大于1.0s时的反应谱低于经验预测模型,表明此次地震近场地震动具有显著的方向性效应.(2)破裂传播的方向性效应主要影响周期超过1.0s的长周期,而对PGA以及周期小于1.0s的短周期地震动影响较弱.在破裂传播前方,周期1.0～10.0s的加速度反应谱值被增强到整体观测平均水平的1.16～1.52倍;在破裂传播后方,周期1.0～10.0s的加速度反应谱值被减弱到整体观测平均水平的0.36～0.70倍.(3)此次地震破裂方向性效应的影响表现出明显的窄带效应,破裂方向性的影响(包括破裂传播前方的增强作用和破裂传播后方的减弱作用)在周期T=3.0s时达到最大,在该周期破裂传播前方的增强系数为1.52,破裂传播后方的减弱系数为0.36.从周期T=3.0s到10.0s,破裂方向性效应的影响随周期增大总体上呈减弱趋势,这与2016年日本熊本M_W7.0地震破裂方向性效应的影响特点显著不同. 相似文献
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9.
采用小波方法筛选出了180条断层距在20 km之内且PGV大于10 cm/s的具有速度脉冲特征的近断层地震波,分别对基岩和土层场地、走滑(SS)和非走滑(NSS)断层、不同脉冲峰值标准情形下近断层脉冲周期和矩震级的关系进行了统计,得到了不同情形下脉冲周期-震级经验公式回归系数,以供近场地震动速度脉冲的相关研究参考使用。结果表明:走滑断层产生的脉冲周期比非走滑断层的大,但随震级的增大情况发生变化;无论走滑断层还是非走滑断层,当震级较小时,土层场地的脉冲周期比基岩场地的大,随着震级的增加,基岩场地的脉冲周期将比土层场地的大;根据不同标准的速度脉冲峰值PGV记录,得到的周期-震级关系曲线有很大区别。 相似文献
10.
近断层地震动的向前方向性效应和永久地面位移效应导致其速度时程表现为长周期、大峰值的速度脉冲，其位移时程表现为阶跃型脉冲. 针对这些特点，同时考虑向前方向性效应和永久地面位移效应，提出了一种简单的、连续函数形式表达的等效速度脉冲模型. 在该模型中，包含描述速度脉冲周期、峰值和形状的5个待定参数，方便了实际脉冲型地震记录的拟合及模拟. 等效速度脉冲模型只包含单一的频率成分，不能反映脉冲型地震记录的高频成分. 根据对11次地震28条地震记录的分析， 速度脉冲的频率一般小于1Hz. 因此， 在模拟脉冲型地震记录的方法中，分别模拟低频脉冲成分和高频成分，并将两者叠加生成近断层脉冲型地震动的模拟时程. 相似文献
11.
Effect of source parameters on forward-directivity velocity pulse for vertical strike slip fault in half space 总被引：1，自引：0，他引：1
It has been found that the large velocity pulse is one of the most important characteristics of near-fault strong ground motions. Some statistical relationships between pulse period and the moment magnitude for near-fault strong ground motions have been established by Somerville （1998）; Alavi and Krawinkler （2000）; and Mavroeidis and Papageorgiou （2003）, where no variety of rupture velocity, fault depth, and fault distance, etc. were considered. Since near-fault ground motions are significantly influenced by the rupture process and source parameters, the effects of some source parameters on the amplitude and the period ofa forward-directivity velocity pulse in a half space are analyzed by the finite difference method combined with the kinematic source model in this paper. The study shows that the rupture velocity, fault depth, position of the initial rupture point and distribution of asperities are the most important parameters to the velocity pulse. Generally, the pulse period decreases and the pulse amplitude increases as the rupture velocity increases for shallow crustal earthquakes. In a definite region besides the fault trace, the pulse period increases as the fault depth increases. For a uniform strike slip fault, rupture initiating from one end of a fault and propagating to the other always generates a higher pulse amplitude and longer pulse period than in other cases. 相似文献
12.
基于显式有限元方法和运动学震源模型并利用昆明盆地三维地下构造模型,本文研究了震源参数对断层附近长周期地震动的影响.结果表明,断层的破裂方式、埋藏深度、破裂速度以及断层面上位错的不均匀分布对断层附近长周期地震动有重要影响.不同破裂方式下,破裂的方向性强的区域分布不同,由于破裂的方向性效应和复杂场地条件的共同作用,导致不同破裂方式的断层附近地震动分布差别很大.随着破裂速度的增加,方向性效应更加明显,断层附近的长周期地震动也随之增大;对于浅源地震,随着断层埋深的增加,地震动明显下降.对于埋藏深度很浅的断层,当Asperity靠近断层上沿时,会显著增大其在地表投影附近的长周期地震动.能否合理地估计这些基本震源参数,是预测未来发震断层周围地震动场的关键. 相似文献
13.
近断层速度脉冲与震源机制的关系浅析 总被引：1，自引：1，他引：0
本文初步分析了近断层速度脉冲的成因和特点，主要包括方向性效应与滑冲效应，并通过中国台湾集集地震的脉冲记录，分析了断层破裂方向和位移大小等震源参数对脉冲强度的影响。此外，基于有限移动源理论，说明了断层辐射与速度脉冲分布的关系，并探讨了利用运动学震源模型研究近断层地震动对速度脉冲影响的技术路线；评述了7种典型的等效速度脉冲模型，建议进一步研究等效速度脉冲函数与震源机制之间的关系。最后，简述了不同类型的断层引起速度脉冲的差异，并推测了产生脉冲型地震动的下限条件，同时展望该研究在地震预警方面的可能性。 相似文献
14.
地震时若断层发生超剪切破裂,地震灾害会显著加剧.因此研究超剪切破裂的形成机理有着非常重要的科学意义.本文利用动力有限单元方法,模拟断层破裂从初始断层跳跃传播到另一条平行的次级断层(断层阶区)时破裂速度的变化情况,并分析断层阶区几何特征等物理参数对产生超剪切地震破裂的促进作用.计算结果表明,断层阶区的诸多物理因素(如:重叠长度、相隔距离以及摩擦系数等)都会对破裂的传播速度产生影响.在一定条件下,破裂传播速度会由在初始断层上的亚剪切波速度,转换为在次级断层上的超剪切波速度.在破裂速度转换过程中,断层间隔起着重要作用,当断层阶区中两断层垂直间隔距离小到一定程度时,破裂跳跃阶区后,破裂速度不会发生变化.所以对于分段断层(可视为一种特殊的断层阶区),由于其断层垂直间隔为0,也就不会出现破裂速度变化的现象,模拟结果对此也进行了证实.然而,若断层间隔太大,当其距离超过一定的限度后,破裂通常无法跨越断层阶区继续传播,而是终止在初始断层上.模拟结果还表明,初始断层与次级断层之间的重叠距离也十分重要,只有当断层阶区中两平行断层之间的重叠部分达到一定长度后,断层的破裂速度才有可能发生转换.此外,计算结果显示,破裂过程中断层面上的应力变化可能是破裂传播速度发生转换的直接原因.最后,模拟还发现,当破裂跨越断层阶区发生速度转换时,破裂需要停顿一定的时间,以便积聚足够的能量来实现破裂速度的增快. 相似文献
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Comparison of source parameters estimated in the frequency and time domains for seismic events at the Rudna copper mine,Poland 总被引：3，自引：0，他引：3
Source parameters estimated in the frequency domain for 100 selected seismic events from the Rudna copper mine, with moment
magnitude ranging from 1.4 to 3.6, were collected to study their scaling relations and to compare them with the parameters
estimated in the time domain. The apparent stress and static stress drop, corrected for the limited bandwidth recording, increase
slightly in a similar manner with increasing seismic moment. The ratio of apparent stress to static stress drop, a measure
of radiation efficiency, is practically constant and its mean value is close to 0.1.
For 37 seismic events, with moment magnitude between 1.9 and 3.4, source parameters were estimated in the time domain from
relative source time functions, that displayed unilateral rupture propagation, and their rupture velocity could be estimated.
It ranges from 0.23 to 0.80 of shear wave velocity and is almost independent of seismic moment. The fault length, estimated
from the average source pulse width and rupture velocity, is clearly dependent on seismic moment and is smaller than the source
radius estimated from the corner frequency on the average by about 25 percent. There is no correlation between the values
of static stress drop estimated in the frequency and time domains, but the time domain stress drop is in general similar to
that estimated in the frequency domain. The apparent stress increases with increasing rupture velocity, and the ratio of apparent
stress to static stress drop seems also to depend on rupture velocity. 相似文献
16.
Pulse-like ground motion observed during the 6 February 2023 MW7.8 Pazarcık Earthquake (Kahramanmaraş, SE Türkiye) 
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下载免费PDF全文 Fan Wu Junju Xie Zhao An Chenghao Lyu Tuncay Taymaz Tahir Serkan Irmak Xiaojun Li Zengping Wen Baofeng Zhou 《地震科学（英文版）》2023,36(4):328-339
In this study, we analyzed 100 three-component strong ground motion records observed within 200 km of the causative fault of the 6 February 2023 MW7.8 Pazarcık (Kahramanmaraş) Earthquake in SE Türkiye. The wavelet method was utilized to identify and analyze the characteristics of pulse-like ground motions in the near-fault region, while considering the uncertainty of the pulse orientation during the analysis. Our investigation focused on the effects of the focal mechanism and rupture process on the spatial distribution, pulse orientation, and maximum pulse direction of the observed pulse-like ground motion. We also analyzed the amplitude and period of the observed ground pulses and the effect of long-period amplification on the ground motion response spectra. Our results indicated the following: (1) A total of 21 typical ground velocity pulses were observed during this earthquake, exhibiting complex characteristics due to the influence of the strike-slip mechanism and rupture directivity. Most ground pulses (17 out of 21) were recorded within 20 km of the fault, in a wide range of orientations, including normal and parallel to the fault direction. The waveforms exhibited unidirectional features, indicating the effects of left-lateral fault slip. Distinct pulses observed more than 20 km from the fault were mainly oriented normal to the fault. The waveforms were bidirectional with double- or multi-round trips as a result of rupture directivity. (2) The amplitudes of the observed pulses ranged from 30.5 to 220.0 cm/s, with the largest peak velocity of 220.0 cm/s observed at Station 3138. The pulse periods ranged from 2.3 to 14.5 s, with the longest pulse period of 14.5 s observed at Station 3116. The amplitude and period of the pulses observed during this earthquake were comparable to those of similar-magnitude global earthquakes. The amplitude of the pulses decreased significantly with increasing fault distance, whereas the pulse period was not significantly affected by the fault distance. (3) Compared with non-pulse records, the velocity pulse records had a pronounced amplification effect on the acceleration response spectra near the pulse period, with factors ranging from 2.1 to 5.8. The larger velocity pulses also significantly amplified the velocity response spectra, particularly over the long periods. This significant amplification effect of the pulses on the response spectra leads to empirical models underestimating the long-period earthquake ground motion. 相似文献
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18.
Preliminary analysis of the hanging wall effect and velocity pulse of the 5.12 Wenchuan earthquake 总被引：3，自引：2，他引：1
A preliminary study of the PGA attenuation, hanging wall effect and velocity pulse characteristics from the 2008 Wenchuan earthquake of Ms =8.0 is described in this paper. The study was carried out through analyses in the time and frequency domains of main earthquake records. In the PGA attenuation study, records from 316 stations less than 1000 km from the surface rupture of the fault were used as a database and attenuation relationships were developed and compared with some existing relationships that are widely used in mainland China, Chinese Taiwan and the US. At the same time, records from 28 stations less than 100 km from the fault were used to study the hanging wall effect and velocity pulse characteristics of this earthquake based on the distribution of PGA, PGV, spectral acceleration, and the velocity pulse peak, and the results are compared with the 1999 Chi-Chi earthquake. In addition, the large PGAs of the UD components observed in this event are also discussed in this paper. From the results of the preliminary study, some conclusions are developed and suggestions for further research are proposed. 相似文献