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2013年4月20日的芦山7.0级地震是继2008年5月12日汶川8.0级特大地震之后,发生在龙门山断裂带上的又一次大震级逆冲型地震.与汶川地震相比,芦山地震的发震断层没有地表出露,断层的滑动角更大,其逆冲性质更强烈.本文挑选了芦山地震中断层距小于200km的45条强震动记录,基于地震动衰减关系进行统计分析,对比了上盘和下盘台站地震动参数相对于衰减关系的对数残差.结果表明：芦山地震的上下盘效应明显,近断层上盘地震动的高频成分要高于同断层距的下盘;上盘地震动衰减要明显快于下盘.地震动衰减关系用简单的一个距离参数很难描述近场断层尺寸效应的影响,也很难模拟地震动上下盘效应.因此,在近场强地面运动模拟中,应多考虑有限断层模型,以模拟断层的尺寸效应. 相似文献
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选取分布在北川-映秀中央断裂两侧断层距120 km以内的40个强震动台站的记录,对汶川地震近断层地震动竖向和水平向加速度峰值、速度峰值、竖向和水平向加速度反应谱及谱比值进行了统计分析.研究表明:(1)地震动加速度峰值有显著的上盘效应,经验衰减模型的结果表明,在距地表破裂3~60 km的范围内,龙门山发震断层上盘一侧竖向与水平向的加速度峰值要比衰减模型得到的平均值大30%~40%.上盘的加速度峰值残差大部分是正值,而断层下盘残差大部分为负;水平地震动的东西分量幅值总体要大于南北分量,东西分量衰减相对较慢.(2)地震动长周期成分较弱,加速度反应谱值随周期增大而迅速减小,在周期1.0 s 时,即使在靠近中央断裂的最大加速度反应谱值也只有0.5 g;地震动加速度反应谱谱比值(竖向/水平向)沿龙门山断层周围的分布,在较长周期(T=0.2 s, 0.5 s, 1.0 s)与短周期(T=0.05 s, 0.1 s)有明显的不同.(3)近断层竖向地震动显著,地震动加速度峰值比在(竖向/水平向)可达1.4.在龙门山发震断层的上盘,地震动加速度峰值比整体上比下盘要大,竖向地震动尤为剧烈.部分近断层记录的地震动谱比值(竖向/水平向)在短周期(< 0.1 s)甚至超过1.5,统计分析还表明谱比值在短周期段(< 0.1 s)随断层距的增大而减小. 相似文献
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1999年9月21日（当地时间）台湾集集7.6级地震是一个逆断层型地震．用回归分析法对台湾集集地震的加速度峰值数据进行分析，得出了这次地震的水平与垂直向的加速度峰值衰减关系．从残差分布上看，位于断层上盘和下盘上的加速度峰值与从衰减关系所得到的结果相比存在不同的系统偏差，断层上盘地表的加速度峰值较高，而下盘地表的加速度峰值较低．从这次地震的加速度峰值分布等值线图上也可以看出，加速度峰值的分布相对于断层呈现明显的不对称性，上盘衰减较慢而下盘衰减较快．在近断层强地面运动研究、地震危险性分析、设定地震研究与震害预测等工作中，应考虑可能地震的震源机制特点，以便使所用的衰减模型更能反映不同地震环境地区的地震动分布特征． 相似文献
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为深入理解汶川地震破裂的构造运动机制,本文选取典型的观测点,利用多种地质地貌标志测绘分析得到了汶川MS8.0地震发震断裂的近地表三维同震滑移矢量.结果显示,北川—映秀断裂上的白水河—高川破裂段北西盘沿88°方位角水平滑移2.58 m、垂直滑移3.70 m;安县—灌县断裂上的白鹿—汉旺破裂北西盘沿134°方位角水平滑移1.63 m,垂直滑移2.00 m;小鱼洞破裂带南西盘沿76°~79°方位角水平滑移2.15~2.71 m,垂直滑移1.36~1.51 m.平行的白水河—高川破裂段和白鹿—汉旺破裂段合计形成1.72 m右旋走滑和3.49 m垂直断裂带的NW向水平缩短,总滑移方向（106°）与断裂带整体走向（42°）呈64°夹角,整个龙门山推覆构造带处于斜向挤压的构造环境.结合震源过程反演成果的分析显示,斜滑的白水河—高川破裂段和逆冲型白鹿—汉旺破裂段可能是在汶川地震中最大的一次子事件过程以滑移分解的形式而同时破裂形成的,滑移分解作用使两条断裂以斜滑与逆冲组合的力学性质产生破裂而非相同性质的斜滑破裂.小鱼洞破裂以低角度斜滑为主,可能是安县—灌县断裂与北川—映秀断裂以滑移分解形式同时破裂的纽带.小鱼洞断裂是龙门山断裂带长期处于斜向挤压的构造环境的产物,不只是逆冲断裂系中的捩断层. 相似文献
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Characteristics of amplitude and duration for near fault strong ground motion from the 1999 Chi-Chi, Taiwan Earthquake 总被引：2，自引：0，他引：2
A great number of free-field ground motion records are obtained during the 1999 Chi-Chi, Taiwan, earthquake. Records from 130 near fault free-field stations within 55 km to the causative fault surface are used as database, and characteristics of earthquake peak ground acceleration, velocity, displacement and duration are analyzed. According to this study, near fault ground motions are strongly affected by distance to fault, fault rupture directivity, site condition, as well as thrust of hanging wall. Compared with empirical strong ground motion attenuation relations used in China, US and Japan, the PGAs and PGVs recorded in this earthquake are not as large as what we have expected for a large earthquake as magnitude 7.6. However, the largest PGV and PGD worldwide were recorded in this event, which are 292 cm/s and 867 cm, respectively. Caused by nonlinear site effects of soil, peaks and corresponding ratios on E-class site were markedly different from those on other sites. Just as observed in historic earthquakes, fault rupture directivity effects caused significant differences between peaks of ground motion of two horizontal components, but took very slight effects on the duration of ground motion. The significant velocity pulses associated with large PGVs and PGDs, as well as large permanent displacements, which may result from the large thrust of the hanging wall, became the outstanding character of this event. Based on this study, we point out that 3D waveform modeling is needed to understand and predict near fault ground motion of large earthquakes. 相似文献
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According to the epicenter distance and the site classification, the 404 groups of earthquake recordings of the main shock of the Chi-Chi, Taiwan China earthquake in 1999 are catalogued. Based on these data, we analyze the statistical features of duration, PGA, envelopes and the response spectra ratio of the horizontal and vertical components of the acceleration recordings. The results of these analyses show that the effect of site classification on the acceleration of various components is obvious; furthermore, fault direction also has certain effects on the characteristics of the horizontal components of ground motion. The detailed research results are as follows： （ 1 ） the duration of the horizontal components of acceleration records increases with the softening of the site; （2） the direction of fault slip has some effects on PGA＇s attenuation features; （3） the average envelopes of acceleration records at different distances and site dames are basically single peak functions of time and the envelopes of horizontal and vertical components of ground motion are obviously different; （4） with the same epicenter distance, EW/NS response spectrum ratios tend to approximate 1.0 as the site becomes softer and the period shorter. V/H response spectrum ratios in short periods （〈 0. 1s） increase with the softening of site, however, V/H ratios within the long-period range （ 〉 characteristic period） decrease with the softening of the site, and the decrease of V/EW ratio speeds up relatively. 相似文献
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利用自动经验基线校正方法,分析2013年4月20日芦山MS7.0级地震13个近场强震动台的观测资料,以估算同震位移场分布,并据此反演了震源滑动模型.经与GPS结果比较,两种不同方法给出的芦山7级地震的水平近场同震位移场幅度都不超过cm级,均显示为典型的逆冲型地震（兼有少量左旋走滑错动）.强震最大水平和垂直永久位移分别为4.9 cm和4.4 cm,分别出现在51YAM台和51QLY 台.两种资料反演的震源滑动模型虽显示多事件特征,但主要滑动均集中在第一次事件,即初始滑动点两侧的走向长约30 km、倾向长约25 km的相对集中的较小范围内,强震和GPS模型的最大滑动量分别为1.14 m和1.09 m,较为一致.其余子事件滑动量小且分布零散,不能排除其数值效应的因素.反演矩震级均在Mw6.7左右,地表破裂应该不明显.文章还讨论了目前在我国利用近场强震动记录估计Mw6~7级地震同震位移场存在的困难和问题,为今后类似工作提供参考. 相似文献
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The 2008 Wenchuan earthquake with Mw7.9 occurred at Yingxiu County in Longmenshan thrust fault belt, southwest China, having triggered a huge amount of slope failures. This paper applied a detailed inventory with more than 190,000 slope failures and strong ground motion records of 187 seismic stations to analyze the qualitative and quantitative relations between slope failure distribution and seismic parameters. The results revealed that slope failure distribution was exponentially decreased with the increment of epicentral distance and distance from surface fault rupture; peak ground acceleration (PGA) on the hanging wall side was apparently larger than that on footwall side. Linear correlation between concentration of slope failures (LNC) and the percentage of the area affected by slope failure (LAP) and PGA was demonstrated by statistical analysis, which revealed that 0.18~0.21 g horizontal PGA was the threshold value of the occurrence of slope failure. Furthermore, this paper presented an empirical model for the attenuation relation of slope failure distribution. 相似文献
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利用高分辨光学影像获取的同震水平位移场资料联合远场波形数据反演获得了2013年巴基斯坦俾路支MW7.7地震的震源过程模型.结果显示这是发生在具有弧形铲状几何形态的Hoshab断层上的一次左旋走滑为主要运动特征的强烈地震事件.推断这种具有罕见运动模式的强烈地震是斜向应力场与特殊的断层几何形态共同作用的结果.研究工作中采用大数据量均匀分布的同震位移资料参与反演计算,结果表明这种以完整图像的形式使用位移场资料的方式可以克服资料可能存在的系统误差获得可信的结果. 相似文献
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利用强震数据获取汶川地震近断层地面永久位移 总被引：2，自引：2，他引：0
利用汶川地震中得到的靠近映秀—北川主断裂的64个强震台站的三分量记录数据, 对加速度记录进行基线校正的基础上获取近断层地面运动的永久形变位移, 并将由强震记录获取到的地面位移结果与GPS观测到的同震位移进行对比分析, 研究汶川MS8.0地震的近断层地面运动的位移特征. 结果表明: ① 在靠近映秀—北川主断层的上盘和下盘, 东西相向的地面运动非常剧烈. 下盘的51SFB, 51MZQ和51JYH台东西向位移均为负(即地面运动向西), 其中51SFB台位移量最大, 达到1.49 m; 上盘的51WCW台位移向东, 位移量为1.26 m. ② 地面运动的位移分布主要表现为以龙门山断裂带的映秀—北川断裂为核心的相向运动, 东西方向上的永久位移要大于南北方向. 从断层机制上来讲, 断层的错动以逆冲运动为主(即逆冲位移要大于走滑分量的位移), 这与震源机制反演及地质考察的结果一致. ③ 大的地面永久位移集中分布在以龙门山断裂带为中心的狭长范围内, 离开发震断裂地面位移的衰减很快. 相比而言, 在发震断层的下盘一侧(即四川盆地)的地面位移的衰减比上盘一侧明显要快. 相似文献
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根据三分量强震动传感器水平摆和竖向摆对倾斜的动力响应差异,利用谱比法计算出汶川MS8.0地震中近断层强震动的断层法线方向和平行方向的同震地面倾斜. 结果表明, 本次地震中强震动观测台处地面倾斜一般小于1deg;,影响频段主要在0.1 Hz以下,发生较大倾斜的台站主要在距地表破裂迹线30 km以内,在100 km之外或水平向加速度幅值均方根在200 cm/s2以下时很少发生0.01deg;以上的同震地面倾斜．总体上看,上盘区域的倾斜值普遍小于下盘区域,法线方向倾斜值一般大于平行线方向倾斜值．位于前山断裂与中央断裂之间区域的绵竹清平台谱比较低但平缓且频带较宽,可能反应了该区域的运动特殊性,而汶川卧龙台则显示了上盘边缘区域地面倾斜较大．逆冲段与走滑段台站倾斜对比显示,地面倾斜可能受局部场地条件影响较大． 相似文献
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2008年5月12日MS8.0 汶川大地震的主要发震断层是龙门山断裂带的映秀—北川断裂.本研究通过地震后的实地调查和地震前后高空间分辨率航空与卫星影像的解译,对映秀—北川断裂带北川段（擂鼓镇—曲山镇）同震地表破裂带的几何学与运动学特征及相关地震地质灾害进行了详细分析.研究结果表明5·12汶川大地震沿映秀—北川断裂带产生的地表破裂带正穿过北川县城—曲山镇中心,并在曲山镇周围诱发了一系列大型滑坡和岩崩等地质灾害,致使北川县城遭到毁灭性破坏.野外考察表明北川段最大逆冲量和右旋走滑量都达8~10 m,这也是映秀—北川地表地震破裂带中位移量最大的地段.同时,值得注意的是曲山镇一带正是地震断层几何学和运动学特征改变的转换地带：曲山镇及其南西部断层倾向北西,呈现以逆冲为主兼右旋走滑的特征;在曲山镇北东断层倾向南东,表现为右旋走滑分量与垂直分量相当,走滑活动特征更明显.研究结果还表明,逆冲-走滑型（或斜向逆冲型）同震地表破裂带的几何学和运动学特征直接影响地震地质灾害及其破坏程度,地震地质灾害的分布表现出明显的不对称性：断层NW盘（上盘）远远强于SE盘（下盘）.地震断层的几何学特征与断层运动的应力及坡向的自由面之间相互作用,加强了滑坡、岩崩等地质灾害的破坏力.因此,汶川大地震为我们研究逆冲-走滑型同震地表破裂的几何学、运动学特征及其地震地质灾害效应提供了契机. 相似文献
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GPS data from Crustal Movement Observation Network of China (CMONOC) are used to derive far-field co-seismic displacements induced by the Mw 9.0 Tohoku Earthquake. Significant horizontal displacements about 30 mm, 10 mm, and 20 mm were caused by this large event in northeast China, north China, and on the Korean peninsula respectively. Vectors of relatively large horizontal displacements with dominant east components pointed to the epicenter of this earthquake. The east components show an exponential decay with the longitude, which is characteristic of the decay of the co-seismic horizontal displacements associated with earthquakes of thrust rupture. The exponential fit of the east components shows that the influence of the co-seismic displacements can be detected by GPS at a distance of about 3200 km from the epicenter of the earthquake. By considering the capability of the far field displacements for constraining the inversion of the fault slip model of the earthquake, we use spherically stratified Earth models to simulate the co-seismic displacements induced by this event. Using computations and comparisons, we discuss the effects of parameters of layered Earth models on the results of dislocation modeling. Comparisons of the modeled and observed displacements show that far field GPS observations are effective for constraining the fault slip model. The far field horizontal displacements observed by GPS are used to modify the slips and seismic moments of fault slip models. The result of this work is applicable as a reference for other researchers to study seismic source rupture and crustal deformation. 相似文献
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Rupture model of the 2013 M_W 6.6 Lushan (China) earthquake constrained by a new GPS data set and its effects on potential seismic hazard 
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下载免费PDF全文 Vertical records are critically important when determining the rupture model of an earthquake, especially a thrust earthquake. Due to the relatively low fitness level of near-field vertical displacements, the precision of previous rupture models is relatively low, and the seismic hazard evaluated thereafter should be further updated. In this study, we applied three-component displacement records from GPS stations in and around the source region of the 2013 MW6.6 Lushan earthquake to re-investigate the rupture model.To improve the resolution of the rupture model, records from both continuous and campaign GPS stations were gathered, and secular deformations of the GPS movements were removed from the records of the campaign stations to ensure their reliability. The rupture model was derived by the steepest descent method(SDM), which is based on a layered velocity structure. The peak slip value was about 0.75 m, with a seismic moment release of 9.89 × 10~(18) N·m, which was equivalent to an M_W6.6 event. The inferred fault geometry coincided well with the aftershock distribution of the Lushan earthquake. Unlike previous rupture models, a secondary slip asperity existed at a shallow depth and even touched the ground surface. Based on the distribution of the co-seismic ruptures of the Lushan and Wenchuan earthquakes, post-seismic relaxation of the Wenchuan earthquake, and tectonic loading process, we proposed that the seismic hazard is quite high and still needs special attention in the seismic gap between the two earthquakes. 相似文献
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Effects of the hanging wall and footwall on peak acceleration during the Jiji (Chi-Chi), Taiwan Province, earthquake 总被引：2，自引：0，他引：2
Introduction In the study of ground motion attenuation model the considered parameters are generally sim-plified as ground motion parameters (acceleration, velocity, displacement, response spectrum, dura-tion, etc), earthquake magnitude, distance and site condition. As the accumulation of ground motion records, it was found that the characteristic of ground motion attenuation in tectonicly compressional region was different from that in tectonicly tensional region and the peak ground accelerat… 相似文献
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基于数值格林函数法的近场强地震动数值模拟方法,以1994年Northridge地震断层面上位错量的不均匀分布模式和该地区的地层剪切波速度结构为震源模型和计算模型,做了两个方面的模拟研究:(1)直立走滑断层(断层倾角为90°)情况下,模拟分析了有限断层单侧破裂模式和双侧破裂模式对强地震动特征——破裂方向性和上盘效应的影响;(2)对于倾斜断层(倾角为45°),模拟分析了正断层、逆断层和走滑断层情况下,单侧破裂模式对其强地震动主要特征——破裂方向性效应和上盘效应的影响.结果表明:断层的破裂方式直接影响着地表地震动峰值和矢量分布;在近场区无论直立断层还是倾斜断层,其地表地震动峰值分布所表达的破裂方向性效应显著,位于破裂传播前方的地震动强度大,反映了波前被压缩的趋势,破裂后方地震强度明显变小;倾斜断层引起的上盘效应明显,NS向分量和竖向分量的地表地震动峰值的最大值出现在上盘靠近断层迹线处,EW向分量的峰值在断层迹线两侧呈不对称分布,且逆断层引起的地震动峰值最大,走滑断层的次之,正断层的最小. 相似文献
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利用基于升、降轨InSAR形变场及余震精定位结果反演得到的同震滑动模型,通过PSGRN/PSCMP程序获得同震水平形变场及应力场分布特征,结合玛多MS7.4地震周边形变同震阶变台站分布特征,探讨同震应力场变化与同震阶变台站分布间的关系。模拟得到的水平形变场结果显示,此次玛多地震为左旋走滑运动特征,水平形变量主要集中在巴颜喀拉块体内,其次是北部的柴达木块体;羌塘块体以及祁连块体同震水平位移量较小;昆仑山口-江错断裂作为一条NE倾向的走滑型断裂,断层上盘区域滑动量明显大于下盘,模拟得到的最大水平形变量达1380mm;形变同震阶变的台站主要集中分布在祁连山断裂带中东段以及西秦岭等地区,祁连山断裂带中东段位于此次玛多地震同震正应力变化正值区域,而西秦岭等地区则处于玛多地震同震剪切应力变化的正值区域,即出现同震阶变的台站与同震应力场变化的正值区域具有较好的一致性。 相似文献
20.
Focal mechanism and dynamic rupture process of the Wenchaun M
s8.0 earthquake in Sichuan province on 12 May 2008 were obtained by inverting long period seismic data from the Global Seismic
Network (GSN), and characteristics of the co-seismic displacement field near the fault were quantitatively analyzed based
on the inverted results to investigate the mechanism causing disaster. A finite fault model with given focal mechanism and
vertical components of the long period P-waves from 21 stations with evenly azimuthal coverage were adopted in the inversion.
From the inverted results as well as aftershock distribution, the causative fault of the great Wenchuan earthquake was confirmed
to be a fault of strike 225°/dip 39°/rake 120°, indicating that the earthquake was mainly a thrust event with right-lateral
strike-slip component. The released scalar seismic moment was estimated to be about 9.4×1020-2.0×1021 Nm, yielding moment magnitude of M
w7.9–8.1. The great Wenchuan earthquake occurred on a fault more than 300 km long, and had a complicated rupture process of
about 90 s duration time. The slip distribution was highly inhomogeneous with the average slip of about 2.4 m. Four slip-patches
broke the ground surface. Two of them were underneath the regions of Wenchuan-Yingxiu and Beichuan, respectively, with the
first being around the hypocenter (rupture initiation point), where the largest slip was about 7.3 m, and the second being
underneath Beichuan and extending to Pingwu, where the largest slip was about 5.6 m. The other two slip-patches had smaller
sizes, one having the maximum slip of 1.8 m and lying underneath the north of Kangding, and the other having the maximum slip
of 0.7 m and lying underneath the northeast of Qingchuan. Average and maximum stress drops over the whole fault plane were
estimated to be 18 MPa and 53 MPa, respectively. In addition, the co-seismic displacement field near the fault was analyzed.
The results indicate that the features of the co-seismic displacement field were coincident with those of the intensity distribution
in the meizoseismal area, implying that the large-scale, large-amplitude and surface-broken thrust dislocation should be responsible
for the serious disaster in the near fault area.
Supported by the National Basic Research Program of China (Grant No. 2004CB418404-4) and the National Natural Science Foundation
of China (Grant Nos. 40574025 and 40874026) 相似文献