汶川8.0级地震及余震破裂的地质构造特征   总被引：5，自引：0，他引：5  

田勤俭  刁桂苓  郝平  冯向东  孙晴 《地震》2009,29(1)

汶川8.0级地震是发生在龙门山断裂带上的大地震,文中应用地震地表破裂调查资料、余震分布和震源机制资料,论述了该次地震的主破裂、次级破裂、触发破裂等方面的地质特征.认为该次地震的主破裂长约200 km,分为南、北两段.南段以逆冲破裂为主,由两条破裂带构成,并引起上盘多条近平行的次级断裂带的破裂;北段以右旋逆冲破裂为主,由单条破裂带构成;在主破裂的东北方向,触发了长约100 km的余震活动.汶川8.0级地震的破裂特征,对研究龙门山断裂带其他段落的强震危险性具有重要意义.  相似文献   

The characteristics of magma reservoir failure beneath a volcanic edifice     

Debra M. Hurwitz  Sylvan M. Long  Eric B. Grosfils 《Journal of Volcanology and Geothermal Research》2009

Eruptions fed from subsurface reservoirs commonly construct volcanic edifices at the surface, and the growth of an edifice will in turn modify the subsurface stress state that dictates the conditions under which subsequent rupture of the inflating reservoir can occur. We re-examine this problem using axisymmetric finite element models of ellipsoidal reservoirs beneath conical edifices, explicitly incorporating factors (e.g., full gravitational loading conditions, an elastic edifice instead of a surface load, reservoir pressures sufficient to induce tensile rupture) that compromise previous solutions to illustrate why variations in rupture behavior can occur. Relative to half-space model results, the presence of an edifice generally rotates rupture toward the crest of a spherical reservoir, with increasing flank slope (for an edifice of constant volume) and larger edifices (or greater reservoir scaled depths) normally serving to enhance this trend. When non-spherical reservoirs are considered, the presence of an edifice amplifies previously identified half-space failure characteristics, shifting rupture to the crest more rapidly for prolate reservoirs while forcing rupture closer to the midpoint of oblate reservoirs. Rupture is always observed to occur in the σ_t orientation, and depending on where initial failure occurs rupture favors the initial emplacement of either lateral sills, circumferential intrusions or vertically ascending dikes. Ultimately, integration of our numerical model results with other information, for instance the sequence of intrusion/eruption events observed at a given volcano, can provide useful new insight into how a volcano's subsurface magma plumbing system evolved. We demonstrate this process through application of our model to Summer Coon, a well-studied stratocone on Earth, and Ilithyia Mons, a large conical shield volcano on Venus.  相似文献   

汶川8.0级地震北川县城震害原因分析   总被引：3，自引：1，他引：2  

姜纪沂  迟宝明  谷洪彪  宋洋 《地震研究》2009,32(4)

汶川MS8.0地震中,处于映秀—北川断裂带上的北川县城区地震烈度达Ⅺ度。地震断层活动在地表形成了3条破裂带,城区地表破裂带占总面积的比例超过6.5%,使建筑物遭受严重破坏,并引发了滑坡与崩塌灾害,加剧了震害损失。各种成灾机制之间存在相互耦合现象,不良地质现象发育是导致北川县城区震害程度极为严重的主要原因。  相似文献   

Fault zone structures of northern and southern portions of the main central fault generated by the 2008 Wenchuan earthquake using fault zone trapped waves   总被引：1，自引：0，他引：1  

Songlin Li  Xiaoling Lai Zhixiang Yao  Qing Yang Geophysical Prospecting Center  China Earthquake Administration  Zhengzhou  China Institute of Geophysics  Beijing  China 《地震学报(英文版)》2009,(4):417-424

The rupture process of the May 12,2008 MS8.0 Wenchuan earthquake was very complex. To study the rupture zones generated by this earthquake,four dense temporary seismic arrays across the two surface breaking traces of the main-shock were deployed in July and recorded a great amount of aftershocks. This paper focuses on the data interpretation of two arrays across the central main fault,the northern array line 1 and southern array line 3. The fault zone trapped waves recorded by the two arrays were used to st...  相似文献   

汶川M_S 8.0地震地表破裂带北端位置的修订   总被引：6，自引：1，他引：5       下载免费PDF全文

李传友  魏占玉 《地震地质》2009,31(1):1-8

对汶川MS8.0地震地表破裂石坎乡以北段的野外地质调查显示,这一段地表破裂仍然十分明显。地表破裂并未沿地质填图所标定的位置发育,而是在走向上稍有变化,但清楚的地貌显示它在此段并不是一条新生断裂。与前期工作相比,可观察到的地表破裂又往NE方向延长了约12km。该段破裂位于平武县石坎乡至青川县马公乡窝前村之间,走向为15°～45°,运动学性质主要为右旋走滑逆冲。地震地表破裂显示的同震垂直位移与石坎乡一带相近,为1～2m左右;右旋水平位移略有增加,为2.0～3.0m之间。地表调查的情况显示,地表破裂在北端可能消失在红光乡东河口一带。  相似文献   

甘肃高台合黎山南缘发现地震地表破裂带   总被引：8，自引：6，他引：2       下载免费PDF全文

郑文俊  张培震  袁道阳  葛伟鹏  刘建辉 《地震地质》2009,31(2):247-255

据最新野外考察发现,位于河西走廊中段北部的合黎山南缘断裂东段有2条较新的地震地表破裂带遗迹,破裂带长度分别为7km和10km,保存较为完整,认为其为较近的一次地震活动所致。根据该地区历史地震资料和目前该地区的研究程度,该地震地表破裂带可能与2次历史地震(公元180年表氏8级地震、公元756年张掖-酒泉7级地震)中的其中之一或与一次漏记的历史强地震有关  相似文献   

Near-source ground motion attenuation relationship for PGA and PSA of the vertical and horizontal components     

H. Aghabarati  M. Tehranizadeh 《Bulletin of Earthquake Engineering》2009,7(3):609-635

In this paper, empirical ground-motion models for the vertical and average horizontal components of peak ground-motion and acceleration response spectra from shallow crustal earthquakes are derived using near-source database. These attenuation relationships were derived using a worldwide dataset consisted of corrected and processed accelerograms of 678 strong-motion records recorded with 60 km of the rupture plane of earthquakes between M_w 5.2 and 7.9. Ground motion models are functions of earthquake mechanism, distance from source to site, local average shear wave velocity, nonlinear soil response, sediment depth, depth-to-top of the rupture, hanging wall effects and faulting mechanism.  相似文献   

Attenuation of peak ground accelerations from the great Wenchuan earthquake   总被引：3，自引：1，他引：2  

Dong Wang  Lili Xie 《地震工程与工程振动(英文版)》2009,8(2):179-188

Over 800 accelerograms recorded by 272 ground-level stations during the Wenchuan earthquake are used to analyze the influence of rupture distance, local site conditions and azimuth on peak ground accelerations (PGAs). To achieve a better understanding of the characteristics of ground motions, the spatial distributions of the EW, NS and UD components of PGAs arc obtained. Comparisons between the EW and NS components, the fault-normal and fault-parallel components,and the vertical and horizontal components of PGAs are performed, and the regression formula of the vertical-to-horizontal ratio of PGAs is developed. The attenuation relationship of peak horizontal accelerations (PHAs) is compared with several contemporary attenuation relationships. In addition, an analysis of residuals is conducted to identify the potential effects of rupture distance, azimuth and site conditions on the observed values of PHAs. The analysis focuses on medium-hard soil site conditions, as they provided most of the data used in this study.  相似文献   

汶川M_S8.0地震绵竹县汉旺镇周边地表破裂带展布方式及其震害意义   总被引：2，自引：0，他引：2       下载免费PDF全文

孙昌斌  谢新生  江娃利 《地震地质》2010,32(2):200

2008年5月12日汶川MS8.0地震的震中烈度为Ⅺ度,但位于地震烈度为Ⅹ度区边缘的绵竹县汉旺镇,无论是房屋毁坏情况还是遇难和失踪人员的数目,均高出周边地震烈度Ⅰ度,接近极震区的破坏程度。文中从汉旺镇周边地表地震破裂带展布方式的角度讨论了这种震害加重现象的原因,介绍了位于汉旺镇北面和南面出现的2条相距1.5km呈左阶斜列展布的地表破裂带。其中,位于汉旺镇北侧的地表破裂带,垂直位移1.4m,水平右旋位移0.44m;位于汉旺镇南侧的地表破裂带,垂直位移量由西向东递减,为3.0～0.2m。尽管这2条地表破裂带没有从汉旺镇中心通过,但汉旺镇正位于这2条地表破裂带夹持的左阶阶区,致使阶区内建筑物除遭受来自震源的振动外,又受到阶区内的挤压,由此加重了汉旺镇建筑物的破坏,也显示出地表破裂带对建筑物破坏形式的多样性。汉旺镇汶川MS8.0地震震害实例表明,地表破裂带的阶区,也是遭受地震时破坏加重的特殊构造部位  相似文献   

2010年2月27日智利地震破裂过程快速反演   总被引：2，自引：0，他引：2       下载免费PDF全文

张勇  许力生  陈运泰 《地震学报》2010,32(2):242-244

运用地震破裂过程快速反演方法,在2010年2月27日智利地震发生后,采用全球地震台网(GSN)的宽频带地震资料,反演了这次地震的破裂过程,在震后约3.5小时得到了这次地震破裂过程的反演结果.结果表明,这次智利地震的破裂过程具有如下基本特征:①矩震级为MW8.6;②地震破裂持续时间约为150s;③包括4个滑动量集中分布区域,最大滑动量约为8m,最大滑动速率约为0.8m/s;④这次地震总体上是一次不对称的双侧破裂事件,破裂从破裂起始点(震源)开始,同时向南北两个方向扩展,但以向北扩展的破裂为主.  相似文献