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运用反演理论探讨了由“零频”资料反演大地震震源模式的基本原理和方法,并用大地测量资料反演了1976年唐山7.8级地震的位错模式。得到的结果表明唐山地震的发震构造是一个总体走向为北东49°的右旋-正断层,断层面倾向南东,倾角76°。这个地震的断层长84公里,宽34公里,走向滑动错距459厘米,倾向滑动错距50厘米,地震矩4.3×1027达因-厘米,应力降29巴,应变降4.3×10-5,释放的能量3.7×1023尔格。由形变资料反演的平均错距和地震矩远大于由地震波资料定出的平均错距（270厘米）和地震矩(1.8×1027达因-厘米),它表明在地震区的地壳内震前可能已经发生了无震滑动--断层蠕动。无震滑动的规模比主震还要大一些,它的矩估计约为2.5×1027达因-厘米。唐山地震前虽然没有前震,但是却有规模这么大的“震前蠕动”,这可能是唐山地震与其他许多有前震的地震（如海城地震）的根本区别,它的许多与别的地震不同的前兆可能与此有关。 相似文献
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由地震纵波初动符号的资料,求得了海城地震系列中Ms≥4.0的24个地震的断层面解。主震发生于1975年2月4日,它的一个节面走向N70°W,倾向NE,倾角81°;另一个节面走向N23°E,倾向SE,倾角75°。根据余震的空间分布以及地面形变资料选取N70°W的节面为断层面,主震是发生在这个近乎直立的断层面上的左旋走向滑动,略具正的倾向滑动分量。前震及大多数余震的震源机制和主震的相似,有四个Ms≥4.0的余震的震源机制和主震的迥然不同,表现出滑动向量和主震的滑动向量相反的断层错动方式。这种情况的一种可能的解释是主震时在断层的一些地段发生错动过头。 由野外资料及余震的空间分布资料计算了主震的震源参数。主震断层长70公里,宽20公里,平均错距45厘米,地震矩2.1×1026达因·厘米,应力降4.8巴,应变降7.3×10-6。它是发生在不能积累起较高应力的薄弱地带的一次低应力降的地震。 由地震纵波初动的半周期和振幅的资料计算了81个前震和余震的震源尺度、地震矩、应力降和平均错距。结果表明前震和余震的应力降都比较低,一般在0.1-1巴之间。余震区中有两个应力降相对说来比较高（高于0.8巴）的地区,它们恰好对应于主破裂错动过头的部位。这些结果意味着震前高应力、错动过头、相对高应力降和震源机制反向四者之间 相似文献
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由 P 波初动符号资料在 DJS-6机上计算了主震及17个较大余震的断层面解,并按照有限移动源模式测定了主震及三个最大余震的震源参数.主震是发生在一个近似直立的右旋走滑断层上,走向 N30°E,破裂方式为不对称的双侧破裂,以2.7公里/秒的平均速度向北东传播70公里,向南西传播45公里.测定的主震震源参数例如平均位错136厘米,地震矩1.24×1027达因·厘米,应力降12巴等.大多数ML>5.0的余震是发生在主破裂面附近及主破裂面两端的扩展分支上,该扩展分支位于膨胀符号区并与主破裂偏离80°左右.较大余震的多数亦集中在这两个扩展分支上.本文试图从理论上分析这种断裂扩展的力学特征.对于脆性材料的复合变形情形,破裂不再沿原来平面扩展,而是与原来平面偏离一个角度的另一面内扩展.并提出一个力学模型,计算了断层扩展角,计算结果与观测事实比较吻合.根据以上结果,本文讨论了唐山地震特点及发生的力学条件,认为唐山地震不同于发生在大断层上能用粘滑机制解释的那类地震,它和海城地震类似的是,除水平应力场作用外,还可能有地下物质的变迁,由于这种变迁使局部地壳受到垂直力.它和海城地震不同的是,它发生在一个比较均匀的脆性介质内,因而能够积累能量发生大震而没有前震. 相似文献
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1976年6月9日云南省龙陵地区发生了一次6.2级余震。本文对这次地震的强震记录进行了数值模拟,并通过合成地震图与观测资料的对比,研究了这次地震的断层长度、破裂方式以及位错分布的特点。分析结果得到这次地震是由北向南的右旋走滑型破裂,断层长度约为20km,破裂速度接近0.9倍剪切波速,断层上的平均错距为60cm,平均应力降约为23bar。近场记录中的丰富高频成分表明断层上的位错分布和上升时间分布是极不均匀的,相应的局部错距和局部应力降分别为189cm和200-300bar,远高于其平均值。通过模拟过程可以看出近场记录对于震源断层的长度和破裂方式等都有较强的约束作用,因此分析强震记录是研究震源过程的一种有效手段。 相似文献
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本文根据地震和地震构造等资料，研究华北地区公元1300年以来MS≥6.5级地震的发震断裂的基本参数.利用1966年以来隆尧、海城、渤海和唐山等有仪器记录的地震的相关参数进行回归分析得出了地震烈度Ⅷ度区长轴长度与余震区长轴长度的回归关系式及震级与震源体破裂长度的回归关系式.用余震区长轴长度代替震源体的破裂长度，从而给出各次地震的震源断层破裂长度.利用地震测深的地壳结构构造剖面、地震序列的震源分布、壳内低速层和地壳上部的构造、盆地构造与居里面分布和已知地震震源分布等资料推断了震源破裂的上下界.基于一定的合理假定推导出了断层滑动角的估计方法，并应用于本研究区，得出了各次事件的断层滑动角. 相似文献
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利用远震资料、近场强震资料和合成孔径雷达干涉同震形变资料确定了2017年8月9日精河MS6.6地震的断层面参数及震源破裂细节。为得到可靠的断层几何参数,发展了一套基于InSAR数据滑动分布反演的三维格点搜索流程,对本次地震断层面的走向、倾角和震源深度进行了格点搜索。结果显示,地震断层面走向为95°,倾角为47°,震源深度为14 km。基于搜索得到的断层模型进行破裂过程联合反演的结果显示:精河MS6.6地震为一次单侧破裂事件,最大滑动量约为0.8 m,滑动区域集中在断层面上震源以西5—15 km,沿倾向15—25 km,破裂主要发生在10 km深度以下区域。断层面上的平均滑动角为106°。整个破裂过程释放的标量地震矩为3.6×1018 N·m,对应矩震级为MW6.3。破裂过程持续约9 s,期间的破裂速度约为2.1—2.6 km/s。由于地震破裂主要集中在10 km以下,未来可能需要关注该区域0—10 km发生潜在地震的可能性。 相似文献
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本文给出了邢台、海城、唐山三大地震的震源机制研究结果,并结合其它大震资料,对浅源走滑大震震源过程的特征作了初步探讨.这类地震的P波波形一般都较复杂,可用单断层多重破裂或复断层多重破裂作解释.地震震级愈大,其第一子震的震源持续时间和破裂长度都愈长.发生在活动频繁、贯穿性好的深大断层上的地震与发生在无明显大断层地区的地震相比较,前者的应力降和位错上升速度都比后者的偏低,而且这种差别在第一子震上表现尤其明显. 相似文献
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利用IRIS全球地震台网30°—90°的长周期P波记录, 反演了2008年3月21日新疆于田MS7.3地震的破裂过程, 得到了此次地震的破裂时空图像, 并初步分析了余震分布与主震断层滑动量分布的关系. 结果表明, 此次地震是一个破裂尺度长100 km、 宽20 km的破裂过程; 破裂持续时间约为40 s, 在第13 s时地震矩释放速率达到峰值, 断层面上一次大的破裂行为几乎构成了整个地震的破裂过程. 地震所释放的标量地震矩为4.23×1019 N·m, 其矩震级为MW7.02. 由主震断层静态滑动量分布图可以看出, 整个破裂区以正断左旋走滑为主, 显示出双侧破裂特征, 最大滑动量为151 cm, 位于初始破裂点沿断层出露地表处. 精定位后的余震在断层面上的投影结果显示, 80%以上ML4.0—4.9余震和全部ML≥5.0余震均发生在初始破裂点附近区域及其南西方向, 位于主震破裂滑动位移量迅速减小的区域, 反映了震源区介质强度的不均匀性. 相似文献
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Introduction An earthquake of MS=7.8 occurred near the Gujarat of India on January 26, 2001, which was one of the most deadly earthquakes since there was the record in the Indian history (Bendick, et al, 2001; Gupta, et al, 2001). The USGS of USA determined the origin time of the earthquake to be 3h16min41s (UTC), and the epicenter location to be 70.32篍, 23.40篘. Shortly after the earthquake, the moment tensor solutions or focal mechanisms and other related parameters were offered by s… 相似文献
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The source parameters, such as moment tensor, focal mechanism, source time function (STF) and temporal-spatial rupture process,
were obtained for the January 26, 2001, India, M
S=7.8 earthquake by inverting waveform data of 27 GDSN stations with epicentral distances less than 90°. Firstly, combining
the moment tensor inversion, the spatial distribution of intensity, disaster and aftershocks and the orientation of the fault
where the earthquake lies, the strike, dip and rake of the seismogenic fault were determined to be 92°, 58° and 62°, respectively.
That is, this earthquake was a mainly thrust faulting with the strike of near west-east and the dipping direction to south.
The seismic moment released was 3.5×1020 Nm, accordingly, the moment magnitude M
W was calculated to be 7.6. And then, 27 P-STFs, 22 S-STFs and the averaged STFs of them were determined respectively using
the technique of spectra division in frequency domain and the synthetic seismogram as Green’s functions. The analysis of the
STFs suggested that the earthquake was a continuous event with the duration time of 19 s, starting rapidly and ending slowly.
Finally, the temporal-spatial distribution of the slip on the fault plane was imaged from the obtained P-STFs and S-STFs using
an time domain inversion technique. The maximum slip amplitude on the fault plane was about 7 m. The maximum stress drop was
30 MPa, and the average one over the whole rupture area was 7 MPa. The rupture area was about 85 km long in the strike direction
and about 60 km wide in the down-dip direction, which, equally, was 51 km deep in the depth direction. The rupture propagated
50 km eastwards and 35 km westwards. The main portion of the rupture area, which has the slip amplitude greater than 0.5 m,
was of the shape of an ellipse, its major axis oriented in the slip direction of the fault, which indicated that the rupture
propagation direction was in accordance with the fault slip direction. This phenomenon is popular for strike-slip faulting,
but rather rare for thrust faulting. The eastern portion of the rupture area above the initiation point was larger than the
western portion below the initiation point, which was indicative of the asymmetrical rupture. In other words, the rupturing
was kind of unilateral from west to east and from down to up. From the snapshots of the slip-rate variation with time and
space, the slip rate reached the largest at the 4th second, that was 0.2 m/s, and the rupture in this period occurred only
around the initiation point. At the 6th second, the rupture around the initiation point nearly stopped, and started moving
outwards. The velocity of the westward rupture was smaller than that of the eastward rupture. Such rupture behavior like a
circle mostly stopped near the 15th second. After the 16th second, only some patches of rupture distributed in the outer region.
From the snapshots of the slip variation with time and space, the rupture started at the initiation point and propagated outwards.
The main rupture on the area with the slip amplitude greater than 5 m extended unilaterally from west to east and from down
to up between the 6th and the 10th seconds, and the western segment extended a bit westwards and downwards between the 11th
and the 13th seconds. The whole process lasted about 19 s. The rupture velocity over the whole rupture process was estimated
to be 3.3 km/s.
Foundation item: 973 Project (G1998040705) from Ministry of Science and Technology, P. R. China, and the National Science Foundation of China
under grant No.49904004.
Contribution No. 02FE2026, Institute of Geophysics, China Seismological Bureau. 相似文献
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Coseismic deformation of the 2021 MW7.4 Maduo earthquake from joint inversion of InSAR,GPS, and teleseismic data 
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下载免费PDF全文 Chaoya Liu Ling Bai Shunying Hong Yanfang Dong Yong Jiang Hongru Li Huili Zhan Zhiwen Chen 《地震科学（英文版）》2021,34(5):436-446
The MW7.4 Maduo earthquake occurred on 22 May 2021 at 02:04 CST with a large-expansion surface rupture. This earthquake was located in the Bayan Har block at the eastern Tibetan Plateau, where eight earthquakes of MS >7.0 have occurred in the past 25 years. Here, we combined interferometric synthetic aperture radar, GPS, and teleseismic data to study the coseismic slip distribution, fault geometry, and dynamic source rupture process of the Maduo earthquake. We found that the overall coseismic deformation field of the Maduo earthquake is distributed in the NWW-SEE direction along 285°. There was slight bending at the western end and two branches at the eastern end. The maximum slip is located near the eastern bending area on the northern branch of the fault system. The rupture nucleated on the Jiangcuo fault and propagated approximately 160 km along-strike in both the NWW and SEE directions. The characteristic source rupture process of the Maduo earthquake is similar to that of the 2010 MW6.8 Yushu earthquake, indicating that similar earthquakes with large-expansion surface ruptures and small shallow slip deficits can occur on both the internal fault and boundary fault of the Bayan Har block. 相似文献
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1999年山西大同Ms 5.6地震的震源断层 总被引：9，自引：0，他引：9
大同震区先后在 1989、1991和 1999年发生MS >5地震 ,利用大同遥测地震台网的记录资料进行比较精确的地震序列震源定位 ,结合宏观烈度分布和震源机制解资料 ,详细地分析对比了 3次子序列的异同。结果显示 ,1999年MS5 .6地震的震源断层是走向NWW、长 16km、宽12km、埋深 5km以下、倾角近直立的左旋走滑断层。而前 2个子序列是NNE为主的右旋走滑断层活动所致 ,表明地震破裂方向发生了变化。这种 2个以上方向先后出现、并且强弱有别的地震破裂是普遍存在的 ,表明震源环境的复杂程度与地震序列的类型有关。虽然震区存在NE向的大王村断裂和NW向的团堡断裂 ,但目前没有证据说明震源断层和 2条构造断层连通。 3次子序列的震源断层都是走滑断层 ,也和 2条构造正断层有别。 1999年的子序列可能属于新破裂。 相似文献
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Rupture process of the 2011 Tohoku earthquake from the joint inversion of teleseismic and GPS data 下载免费PDF全文
下载免费PDF全文 Teleseismic and GPS data were jointly inverted for the rupture process of the 2011 Tohoku earthquake. The inversion results show that it is a bilateral rupture event with an average rupture velocity less than 2.0 km/s along the fault strike direction. The source rupture process consists of three sub-events, the first occurred near the hypocenter and the rest two ruptured along the up-dip direction and broke the sea bed, causing a maximum slip of about 30 m. The large-scale sea bed breakage may account for the tremendous tsunami disaster which resulted in most of the death and missing in this mega earthquake. 相似文献
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Temporal and spatial rupture process of the great Kunlun Mountain Pass earthquake of November 14, 2001 from the GDSN long period waveform data 总被引：7，自引：0，他引：7
XU Lisheng & CHEN Yuntai Institute of Geophysics China Seismological Bureau Beijing China 《中国科学D辑(英文版)》2005,48(1):112-122
The temporal and spatial rupture process of the 14 November 2001 Kunlun Mountain Pass earthquake (KMPE) is obtained by inverting the high signal-to-noise-ratio P-waveform data of vertical components of 20 stations with epicentral distances less than 90°, which are of Global Digital Seismogragh Network (GDSN). The inverted results indicate that the KMPE consists of 3 sub-events. The rupture of the first sub-event initiated at the instrumental epicenter (35.97°N, 90.59°E) and then propagated both westwards and eastwards, extending 140 km westwards at the speed of 4.0 km/s and 80 km eastwards at the speed of 2.2 km/s, which appeared to be an asymmetrical bilateral rupture dominantly from east to west. This sub-event formed a 220-km-long fault. Fifty-two seconds after initiation of the first sub-event, at which time the first sub-event was not over but in its healing phase, the rupture of the second sub-event initiated 220 km west of the epicenter and propagated both westwards and eastwards, extending 50 相似文献
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基于有限断层模型反演方法,我们利用区域宽频带数据反演得到了2014年8月3日鲁甸MS6.5级地震的震源破裂过程.反演结果显示：此次地震的发震断层走向为北北西向,破裂主要以左旋走滑为主,位移主要发生在震源左上方,最大滑动量为0.7 m,模型显示断层破裂可能接近地表,破裂长度约10 km.此次地震释放的标量地震矩为1.97×1018 N·m,相当于矩震级为Mw 6.1,地震能量主要在前15 s释放.鲁甸地震有四个显著的特点：（1）位移主要集中在浅部,从11 km起破点开始迅速向上传播,大部分位于10 km以上且最大位移位于深度3 km处,从模型来看,破裂可能接近地表,因此地表震动较为强烈;（2）应力降比较大,计算显示释放的同震静态应力降约为2.8 MPa;（3）破裂速度较快,在地表附近超过了2.5 km·s-1;（4）主震可能发生在一个共轭断层系上.这四个特点可能是导致此次地震造成如此重大人员伤亡和财产损失的最重要的原因. 相似文献