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1.
Spontaneous Complex Earthquake Rupture Propagation 总被引：1，自引：0，他引：1
S. Das 《Pure and Applied Geophysics》2003,160(3-4):579-602
— The historical development of spontaneous rupture propagation, starting from the landmark paper of Griffith in 1920, through to the late 1980s is traced, with particular emphasis on the work carried out at MIT in the 1970s by K. Aki and his co-workers. Numerical applications of Kostrov's method for planar shear cracks were developed by Hamano, Das and Aki. Simultaneously at MIT, Madariaga considered the radiated field of a dynamic shear crack. The further development of these ideas, for example, three-dimensional spontaneous planar faulting models, continued through the 1980s. Major insight into the maximum possible rupture speeds for earthquakes developed, with the acceptance of the theoretical possibility of supersonic rupture speeds for faults with cohesion and friction, the theoretical developments spurring the search for such observations for earthquake ruptures. Possible mechanisms by which faults stop were elucidated. It was shown that a propagating rupture can jump over barriers for cracks with a cohesive zone at its tip. Complex faulting models, namely the barrier and asperity models, and their associated radiated field developed. In the late 1980s, it was shown that “dynamic” or transient asperities can develop during the complex rupturing process. Even seemingly relatively simple physical situations, can lead to such complex rupturing processes that the usual idea of “rupture velocity” needs to be abandoned in those cases. Some of the work initiated by Aki and his co-workers, such as the details of the transition from sub-Rayleigh to super-shear speeds in inplane shear mode, and the behavior of the cohesive zone size as the crack extends, still remains the subject of research today. 相似文献
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Zheng Wenjun Yuan Daoyang Zhang Dongli He Wengui Guo Hua Liu Baichi 《中国地震研究》2005,19(4):409-419
INTRODUCTIONThe1927GulangMS8.0earthquake is a severe earthquake followed the HaiyuanMS8.5earthquake of1920inthe Qilian Mt._Hexi Corridor earthquake zone.The most severely hit region wasaround Gulang and Liangzhou(the present Wuwei)of Gansu Province,with a… 相似文献
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Zheng Wenjun 《中国地震研究》2005,19(4):409-419
The 1927 Gulang M_S8.0 earthquake is a severe earthquake that followed the Haiyuan M_S8.5 earthquake of 1920 in the Qilian Mt._Hexi Corridor earthquake zone. There are divergences of opinion in the previous studies about the rupture properties of the earthquake. Based on trenching and field investigation, and analysis of historical data, we hold that the earthquake resulted from the joint process of the Tianqiaogou_Huangyangchuan fault, Dongqingding segment of the Huangcheng_Shuangta fault and the Wuwei_Tianzhu buried fault, which constitute the Gulang nappe. By finite_element numerical simulation on the deformation mechanism of Gulang nappe, it is found that the stress and strain mainly concentrate in the western segment of the Tianqiaogou_Huangyangchuan fault, the Dongqingding segment of the Huangcheng_Shuangta fault, and the Gulangxia segment of the Wuwei_Tianzhu buried fault and the Gulang_Shuangta fault. The stress concentration coincides with the distribution of the earthquake surface rupture. It also proves that the earthquake is an outcome of the Gulang nappe activity as a whole. 相似文献
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1927年古浪8级地震的破裂习性及破裂机制的数值模拟 总被引：3，自引：0，他引：3
1927年古浪8级地震是继1920年海原8．5级地震之后发生在海原一祁连山断裂带上的另一次特大地震。对这次地震的破裂习性，前人的研究结果存在较大分歧。本文在多探槽揭露和地面追踪调查基础上，结合相关的历史资料分析后，认为本次地震是由构成古浪推覆体的天桥沟一黄羊川断裂、皇城双塔断裂冬青顶断裂段以及武威一天祝隐伏断裂等共同作用的结果。对古浪推覆体平面和剖面变形机制的有限元数值模拟结果显示，其应力和应变的集中区主要分布在天桥沟一黄羊川断裂西段、皇城一双塔断裂冬青顶一带以及武威一天祝隐伏断裂和古浪一双塔断裂所在的古浪峡一带，这与地震地表破裂带的展布是一致的，同时也进一步说明了1927年古浪8级地震是该推覆体整体活动的结果。 相似文献
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目的：分析外伤性膈肌破裂的影像表现,为临床手术提供有效影像诊断依据。方法：回顾2011年1月～2013年1月两年中经手术救治的15例膈肌破裂的影像表现。结果：15例患者胸腹的平片检查和腹部螺旋CT检查,均能清楚显示膈肌破裂的位置,破裂口大小,膈疝形成及疝囊内容物等,其中CT能显示膈肌中断、膈肌挛缩等特征性征象。结论：膈肌破裂的螺旋CT表现具有特征性,结合平片,能为临床手术治疗提供有效的依据,有极高的诊断价值。 相似文献
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Tracy L. Johnson 《Pure and Applied Geophysics》1978,116(4-5):954-963
Summary Laboratory measurements of rupture and particle velocity are in surprisingly good agreement with seismic values, providing further evidence that stick-slip friction is a suitable mechanism for shallow earthquakes. A simple theory is developed to explain the linear relationship observed between average particle velocity and stress drop for stick-slip events. Both stick-slip ruptures and cracks in brittle material commonly propagate at velocities roughly comparable to theS wave velocity of the material. Rupture normally begins relatively slowly and accelerates to a steady velocity in a few centimeters. Observations suggest that stick-slip ruptures can propagate atS wave speeds or occasionally greater and that cracks in pre-stressed glass can also propagate faster than theS waves. Fracture and thus rupture velocity of intact rock specimens is greatly influenced by the inhomogeneous structure of rock. Fracture may be modeled by coalescence of many cracks rather than growth of a single crack.Lamont-Doherty Geological Observatory Contribution No. 2627. 相似文献
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目的：探讨动态增强CT对肝癌自发破裂伴腹腔内出血型(血腹)的诊断价值。材料与方祛：回顾性分析10例肝癌发生破裂平扫十增强CT表现；分析肝癌破裂的增强CT特征。结果：所有的破裂的肿瘤均位于肝脏的周边带，6例显示了突出于肝边界外的实质。中心坏死7例，肝表面不连续5例。3例‘未发现破裂’的肝癌在增强时发现造影剂外溢至肝边界之外。2例只显示为肿块中出血但手术中发现己发生了破裂。1例整个肝脏破裂，分离的碎块漂浮于大量的腹水中。增强扫描后5例显示了周边带状强化及不连续低密度病灶。结论：增强CT使病灶显示更为清楚，能提高肝癌自发破裂诊断精确度，对临床怀疑肝癌自发破裂造成血性腹水者，增强CT检查十分必要。 相似文献
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2008年汶川大地震造成北川断裂、彭灌断裂、小渔洞断裂等多条断裂的破裂,呈现出复杂的破裂过程. 对此,以往地震学的研究没有对于各个发震断层的破裂先后顺序给出充分论证. 本文计算由于断层破裂在其他断层段上造成库仑应力的变化,根据其相互触发关系确定断层可能的破裂顺序. 结果表明,各断裂带可能的发震顺序为:主震在北川断裂南端(小渔洞断裂以南的北川断裂虹口段)起始,造成北川断裂的后续段落龙门山镇-清平段和彭灌断裂同时破裂,进而触发小渔洞断裂发生破裂. 相似文献
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2014年5月24日在云南省盈江县发生Ms5.6级地震(主震A), 于5月30日在其附近再次发生Ms6.1级地震(主震B). 我们挑选云南省地震台网记录的数字波形资料, 借助于经验格林函数技术提取了这两次地震的震源时间函数,获得了其破裂历史. 为了利用经验格林函数技术提取震源时间函数,我们首先利用优选的速度模型,采用逆时成像技术重新确定了主震A和B以及挑选的6次较大余震的震源位置,并利用双差定位技术确定了主震与余震之间的相对位置;然后利用广义极性振幅技术反演了这些事件的震源机制;最后,根据主震和余震的相对位置以及震源机制特征挑选最优台站记录,提取了两个主震的震源时间函数. 结果表明,主震A持续时间约3.5 s, 分两个阶段,第一阶段0~1.3 s, 第二阶段1.3~3.5 s;主震B持续时间约5.0 s, 其过程比A复杂,至少可以分为五个阶段,第一阶段0~0.7 s, 第二阶段0.7~1.6 s, 第三阶段1.6~2.5 s,第四阶段2.5~3.8 s,第五阶段3.8~5.0 s. 相似文献
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震源动力学中破裂产生的地震动在层状介质中的传播模拟,是地震学以及地震工程学研究的前沿课题之一。本文通过建立精确的三维模型,选取具备灵活网格、高精度高效率计算性能的谱元法,利用有效抑制伪震荡的时间域离散方法——加权速度Newmark方法以及多次透射人工边界条件,进行了SCEC/USGS基准项目中TPV5模型的地震破裂过程模拟,得到基于层状介质模型和均匀介质模型（后者采用相同破裂模型）的埋深2km的震源参数结果。将二者进行对比,并具体分析破裂面位错、地震矩、破裂传播时间、上升时间和地表位移,发现层状介质对破裂过程的传播影响较为明显:① 层状介质的存在整体增加了破裂面上的位错,在层状介质模型下计算得到的地震矩约是均匀介质模型结果的1.3倍,因此认为层状介质增强了地震破裂过程中的能量释放;② 层状介质的存在使得破裂传播至地表的速度减慢,并缩短了地表各点的上升时间,增强了地表的地震动响应;③ 层状介质对于地表位移有着明显的增加作用,同时协同破裂面上的初始应力异常区域对位移峰值中心的改变有显著影响。④ 介质分异面附近地震动强烈。对结果进行整理后发现,在具有地下层状介质的地区要充分考虑层状介质产生的场地效应,否则可能会低估该地区的地震危险性。 相似文献
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Eric L. Geist 《Pure and Applied Geophysics》2013,170(9-10):1475-1491
The effect of distributed coseismic slip on progressive, near-field edge waves is examined for continental shelf tsunamis. Detailed observations of edge waves are difficult to separate from the other tsunami phases that are observed on tide gauge records. In this study, analytic methods are used to compute tsunami edge waves distributed over a finite number of modes and for uniformly sloping bathymetry. Coseismic displacements from static elastic theory are introduced as initial conditions in calculating the evolution of progressive edge-waves. Both simple crack representations (constant stress drop) and stochastic slip models (heterogeneous stress drop) are tested on a fault with geometry similar to that of the M w = 8.8 2010 Chile earthquake. Crack-like ruptures that are beneath or that span the shoreline result in similar longshore patterns of maximum edge-wave amplitude. Ruptures located farther offshore result in reduced edge-wave excitation, consistent with previous studies. Introduction of stress-drop heterogeneity by way of stochastic slip models results in significantly more variability in longshore edge-wave patterns compared to crack-like ruptures for the same offshore source position. In some cases, regions of high slip that are spatially distinct will yield sub-events, in terms of tsunami generation. Constructive interference of both non-trapped and trapped waves can yield significantly larger tsunamis than those that produced by simple earthquake characterizations. 相似文献
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-- Rupture in the heterogeneous crust appears to be a catastrophe transition. Catastrophic rupture sensitively depends on the details of heterogeneity and stress transfer on multiple scales. These are difficult to identify and deal with. As a result, the threshold of earthquake-like rupture presents uncertainty. This may be the root of the difficulty of earthquake prediction. Based on a coupled pattern mapping model, we represent critical sensitivity and trans-scale fluctuations associated with catastrophic rupture. Critical sensitivity means that a system may become significantly sensitive near catastrophe transition. Trans-scale fluctuations mean that the level of stress fluctuations increases strongly and the spatial scale of stress and damage fluctuations evolves from the mesoscopic heterogeneity scale to the macroscopic scale as the catastrophe regime is approached. The underlying mechanism behind critical sensitivity and trans-scale fluctuations is the coupling effect between heterogeneity and dynamical nonlinearity. Such features may provide clues for prediction of catastrophic rupture, like material failure and great earthquakes. Critical sensitivity may be the physical mechanism underlying a promising earthquake forecasting method, the load-unload response ratio (LURR). 相似文献
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1976年龙陵震群序列的破裂特征 总被引：2，自引：1，他引：2
龙陵地震是由８个６级以上地震组成的强震震群序列，采用地震活动图象和震源机制资料的构造分析方法，得到带有运动学和动力学特征的震源破裂组合在地面的投影图象，配合其它资料，提出龙陵地震序列强震的破裂特征是：由３条北东东向左旋走滑断层和２条北北西向右旋走滑断层组成的共轭破裂组合，进一步讨论了某些有关的地震地质问题。 相似文献
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—We analyze the initiation and enlargement of the rupture surface of translational landslides as a fracture phenomenon using a two-dimensional boundary-element method. Both processes are governed largely by the stress field and the pre-existing planes of weakness in a slope. Near the ground surface, the most compressive stress becomes either parallel or perpendicular to the slope, depending on the topography and regional stresses. The shear stress available to drive slope-parallel sliding in a uniform slope thus is small, and therefore pre-existing weaknesses are required in many cases for sliding. Stresses in a uniform slope favor the initiation of sliding near the slope base. Sliding can progress upslope from there in retrogressive fashion. Most slopes are not uniform and notches in a slope will concentrate stresses and generally promote sliding there. As the region of sliding at depth enlarges, the stress concentration near the edge of the area of slip will tend to rise. Stress concentrations can become sufficient to open fractures above and below a basal slide plane, in keeping with observations. If one tip of a slide plane intersects the ground surface, then stresses near the other tip can increase markedly, as can slip. Our analyses show that slope-parallel sliding along a plane at depth will cause downslope extension in the upslope half of a slide mass and shortening in the downslope half, consistent with observations. Displacement profiles that could be interpreted as rotational can result from sliding along such a plane, however careful analysis of surface deformation can be used to understand sliding at depth. 相似文献
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近断层地震动是造成近断层区工程结构破坏的重要因素,近断层地震动的特征受到诸多因素的影响,其中断层破裂传播的方向性是影响近断层地震动及其分布特征的关键因素之一。方向性效应的影响因素众多,比如断层破裂的速度、破裂的方向、断层的倾角、震源的深度、破裂的模式、破裂起始位置以及断层面上的局部震源参数等。但是这些参数是如何影响方向性效应的呢?特别是一般认为断层的破裂速度接近于剪切波传播速度时,会产生明显的方向性效应,但是当破裂速度超过剪切波传播速度时是否会产生方向性效应?如果存在,又会对近断层地震动的特征产生如何影响?为了回答这些问题,本研究首先分析了方向性效应的相关概念,接着采用数值方法模拟了各种震源相关参数的变化对方向性效应的影响,并且对模拟结果和实际近断层强地震动的方向性特征进行了分析,最后专门研究了地震破裂过程中的超剪切破裂现象及其对近断层地震动方向性效应的影响。研究时分别从地震动的加速度、速度和位移三方面,系统地分析了其三分量的峰值、频谱和持时特征,研究的主要内容和结论如下: 相似文献
18.
有关集结相的争论提醒我们需要重新全面理解nucleation的含义．Nucleation的本来含义就是突变过程的集结、成核、起始等,因而,需要研讨如何针对不同领域准确进行翻译．地震集结的基本含义,是指岩体内微破裂的集结导致局部弱化和岩体失稳．狭义集结理论对于解释断层摩擦行为有一定意义,但不应夸大其适用范围．从热力学的角度看,地震集结实际是岩体多种状态参量的变化过程,是跨多学科的研究课题．本文评述了损伤理论、断裂力学、地震破裂动力学和摩擦本构关系的研究,及其在地震集结问题中的应用．介绍了近期若干课题的进展,包括构造环境对地震集结过程影响的研究;利用波速各向异性,特别是剪切波分裂方法测量微破裂集结引起的介质各向异性研究,以及地震集结的辐射温度场的遥感接收的实验研究等．讨论了大地震集结的特征,以及上述研究在强地震前兆中的意义． 相似文献
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We analyze the structure of the Archaean Pretorius fault in TauTona mine, South Africa, as well as the rupture-zone that recently
reactivated it. The analysis is part of the Natural Earthquake Laboratory in South African Mines (NELSAM) project that utilizes
the access to 3.6 km depth provided by the mining operations. The Pretorius fault is a ~10 km long, oblique-strike-slip fault
with displacement of up to 200 m that crosscuts fine to very coarse grain quartzitic rocks in TauTona mine. We identify here
three structural zones within the fault-zone: (1) an outer damage zone, ~100 m wide, of brittle deformation manifested by
multiple, widely spaced fractures and faults with slip up to 3 m; (2) an inner damage zone, 25–30 m wide, with high density
of anastomosing conjugate sets of fault segments and fractures, many of which carry cataclasite zones; and (3) a dominant
segment, with a cataclasite zone up to 50 cm thick that accommodated most of the Archaean slip of the Pretorius fault, and
is regarded as the ‘principal slip zone’ (PSZ). This fault-zone structure indicates that during its Archaean activity, the
Pretorius fault entered the mature fault stage in which many slip events were localized along a single, PSZ. The mining operations
continuously induce earthquakes, including the 2004, M2.2 event that rejuvenated the Pretorius fault in the NELSAM project
area. Our analysis of the M2.2 rupture-zone shows that (1) slip occurred exclusively along four, pre-existing large, quasi-planer
segments of the ancient fault-zone; (2) the slipping segments contain brittle cataclasite zones up to 0.5 m thick; (3) these
segments are not parallel to each other; (4) gouge zones, 1-5 mm thick, composed of white ‘rock-flour’ formed almost exclusively
along the cataclasite-host rock contacts of the slipping segments; (5) locally, new, fresh fractures branched from the slipping
segments and propagated in mixed shear-tensile mode; (6) the maximum observed shear displacement is 25 mm in oblique-normal
slip. The mechanical analysis of this rupture-zone is presented in Part II (Heesakkers
et al., Earthquake Rupture at Focal Depth, Part II: Mechanics of the 2004 M2.2 Earthquake Along the Pretorius Fault, TauTona mine,
South Africa 2011, this volume). 相似文献
20.
云南中甸-大具断裂上新发现的地震地表破裂带 总被引：1，自引：0，他引：1
中甸-大具断裂是川滇菱形块体的西南边界,总体走向310°—320°。近年来我们对该断裂进行了1:50000条带状地质填图,发现了断裂活动的地质地貌证据。其中,在丽江大具盆地内（金沙江右岸）沿断裂新发现一处典型地震地表破裂带,长约600m,宽120m左右,主要表现为地表挤压鼓包、挤压垄脊、张裂缝、挤压阶区等,呈NW走向,与中甸-大具断裂走向基本一致。野外工作中,我们详细记录和测量了地表破裂的破裂样式、破裂规模和相关定量数据,利用旋翼无人机测绘了地表破裂带的形态和展布,获得了高精度DEM,分析了地表破裂表现出的运动性质。在已有资料的基础上讨论了地表破裂的形成时代、归属、震级大小,简要分析了其发震断层。新地震地表破裂带的发现为进一步研究中甸-大具断裂活动特征、古地震及地震危险性提供了基础资料。 相似文献