走滑活动断裂的障碍体与地震破裂的关系

系统收集了中国大陆走滑活动断裂带上障碍体（阶区）与地震破裂的资料,探讨了障碍体止裂尺度与地震破裂的关系及其分段意义。统计分析表明,走滑活动断裂带上地震的震级与障碍体的阶距、阶距与次级段长度具有较好的线性关系。障碍体的阶距可以作为判定地震破裂止裂尺度的极重要标志,是进行破裂分段的前提和基础。     

芦山M_S7.0地震箭杆林地表破裂带研究

中国地震局地球物理勘探中心芦山MS7.0地震现场工作队在地震应急考察期间发现了WNW向的箭杆林地表破裂带,并详细考察了该地表破裂带的产状、破裂面上的擦痕及断错特征,讨论了对该地表破裂带的不同认识以及对发震构造研究的意义.箭杆林地表破裂带位于雅安市上里镇箭杆林村二组西侧海拔1 529—1 578m、坡度30°—40°的山坡上.在长约80m的范围内,该地表破裂带分3段近直线展布,每段长6—10m,最宽约40cm.破裂带总体走向120°,破裂面平整,倾向SW,倾角62°—85°.破裂通过的岩性多为黏土,破裂面上有两组明显的新鲜擦痕,倾伏角较大的一组擦痕一般仅保留在距地面10—20cm以上的范围内,其下倾伏角较小的一组擦痕则覆盖倾伏角较大的一组擦痕.破裂经过处见一直径约4cm的树根被明显错断,上盘上升15cm,并向SE方向平移10cm;另见上盘地层发生翻转现象.经探槽揭示,破裂带上盘黑色腐植土层相对下盘上升约15cm.综合分析表明,箭杆林地表破裂带在芦山MS7.0地震期间经历了先逆冲、后左旋平移的运动过程.震源机制解表明,芦山MS7.0地震是错断面为NE走向的逆冲型地震.WNW向箭杆林地表破裂带可能是芦山地震产生的次级破裂带,是否存在NW--WNW向的发震构造值得研究.芦山MS7.0地震箭杆林地表破裂带的发现为发震构造和震害研究提供了重要的基础资料.     

阿尔金断裂中段南月牙山古地震地表破裂带及其构造意义

阿尔金断裂是青藏高原东北缘的一条重要的边界断裂,其几何结构和运动学性质对青藏高原的构造演化具有重要的指示意义。通过卫星影像解译和野外实地调查,在柴达木盆地西缘、索尔库里盆地南约10km的盐壳区发现一长约14km的古地震地表破裂带。该地震破裂带与阿尔金主走滑断裂近平行,根据几何形态大致可将其分为3段走向不同的次级段落,总体走向为N80°E,但局部段落的走向存在变化。该破裂带的构造样式以挤压隆起、次级断裂、裂槽、三角拉分盆地和断陷盆地为主要特征,多相间出现,是典型的走滑断层上的地震破裂带特征,文中利用野外活动断裂地质填图方法标绘了30余个挤压隆起体。另外,考察中还发现在多数挤压隆起上有多次地震重复活动的证据。根据附近盐壳钻孔年龄和地震裂缝中沉积物的年龄结果推测,最新一次地震事件发震时间的下限为全新世。该地震地表破裂带向E进入大通沟南山,其地貌特征表现为较连续的逆冲陡坎,而向W破裂带逐渐消失。通过地震反射剖面推测认为该破裂带向W与阿尔金断裂平顶山次级断裂相接。作为阿尔金断裂的1个构造节点,平顶山将部分应变传递到青藏高原内部的月牙山-大通沟断裂,其多次活动造成了月牙山东约14km长的地表破裂带...     

1303年山西洪洞8级地震地表破裂带di

综合20世纪90年代初在霍山山前断裂和近年在绵山西侧断裂和太谷断裂获取的最新调查资料，讨论了1303年山西洪洞8级地震地表破裂带的展布和位移特征. 如果太谷断裂、绵山西侧断裂与霍山山前断裂在1303年洪洞地震中同时活动，则该次地震的地表破裂带长163 km，分为3段，即霍山山前断裂段、绵山西侧断裂段和太谷断裂段. 各段长度分别为50，35和70 km，3段之间存在4和8 km的阶区. 该地震地表破裂带具右旋走滑特征，北段和中段右旋走滑位移量6～7 m，南段最大为10 m. 在山西断陷带盆地边界的单条断裂一般只对应7级地震，而该次8级特大地震则突破两个盆地之间的障碍体，显示了强震地表破裂尺度的可变特征.      

1850年西昌地震地表破裂带

着重从1850年西昌地震的地表破裂带调查入手,通过对地表破裂的分布特征、几何特征以及与各次级断层的关系的研究,对这次地震的震级、震中位置和震源深度进行讨论。     

昆仑山口西8.1级地震地表破裂带西段考察

20 0 1年 1 1月 1 4日 1 7时 2 6分 (北京时间 ) ,在我国昆仑山口西新疆维吾尔自治区与青海省交界处发生了 8.1级地震。震区为海拔 4 90 0 m以上的高原和山地。这是新世纪发生在中国境内的第一个 8级大地震。地震发生后 ,中国地震局组织了综合考察队对此次地震进行了全面考察。     

1850年西昌地震地表破裂带

着重从1850年西昌地震的地表破裂带调查入手,通过对地表破裂的分布特征、几何特征以及与各次级断层的关系的研究,对这次地震的震级、震中位置和震源深度进行讨论.     

玉树MS7.1地震地表破裂带及其同震位移分布

2010年4月14日青海省玉树县发生MS7.1地震,野外地质考察及室内遥感解译表明地震形成反L形地表破裂,长约50公里,宏观震中位于郭央烟宋多(33°3′N,96°51′E)。总体上可分为三段,北段与中段间有16km未发现明显地表破裂形迹,中段和南段呈左阶排列,阶区内发育有右阶羽列式破裂。玉树地震最大位移量不小于1.3m,以左行走滑活动为主,兼有挤压逆冲活动。玉树断裂是本次地震的发震断层,断裂南侧羌塘块体和北侧巴颜喀拉块体差异运动导致了玉树地震的发生。地震复发间隔108～185a。破裂南端与1896年强震破裂之间尚有20余公里未发现破裂,其地震危险性还有待进一步研究。     

1850年西昌地震地表破裂带

着重从 1850年西昌地震的地表破裂带调查入手 ,通过对地表破裂的分布特征、几何特征以及与各次级断层的关系的研究 ,对这次地震的震级、震中位置和震源深度进行讨论。     

汶川Ms 8.0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

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     

帕米尔高原1895年塔什库尔干地震地表多段同震破裂与发震构造

基于高分辨率卫星影像解译,通过野外地质地貌填图与差分GPS测量,初步获得了帕米尔高原1895年塔什库尔干地震地表破裂带的空间展布、破裂类型、位移及分布等基本参数,据此估算了可能的地震震级,讨论了其宏观震中及发震构造模型.塔什库尔干地震使得慕士塔格正断层南段的部分和整个塔合曼正断层发生破裂,形成了长约27km的地震地表破...     

活断层地震地表破裂“避让带”宽度确定的依据与方法

基于不同类型活断层产生的地震地表破裂带宽度和跨断层探槽地质剖面的地层强变形带宽度等观测事实 ,结合地面建筑设施毁坏带与活断层密切的空间位置关系 ,采用统计分析方法 ,确定了活断层“避让带”宽度为 30m。各活断层更为准确的避让带宽度可通过分析跨断层探槽地质剖面上地层的变形特征加以验证或修订 ;活断层斜列阶区、平行次级断层围限区、走向弯曲区等特殊地域的避让带宽度为这些地域宽度与两外侧各 15m之和。建议有关部门进行活断层“避让带”立法与执法管理 ,并加强活断层鉴定及其地表活动线几何结构形态的准确定位工作 ,积极而有效地减轻地震灾害     

汶川M_S8.0地震地表破裂带及其发震构造

震后应急野外考察表明,2008年5月12日汶川MS8.0地震在青藏高原东缘龙门山推覆构造带上同时使北川-映秀断裂和灌县-江油断裂两条倾向NW的叠瓦状逆断层发生地表破裂。其中,沿北川-映秀断裂展布的地表破裂带长约240km,以兼有右旋走滑分量的逆断层型破裂为主,最大垂直位移6.2m,最大右旋走滑位移4.9m;沿灌县-江油断裂连续展布的地表破裂带长约72km,最长可达90km,为典型的纯逆断层型地表破裂,最大垂直位移3.5m;另外,在上述两条地表破裂带西部还发育着1条NW向带有逆冲垂直分量、左旋走滑性质的小鱼洞地表破裂带,长约6km。这一地表破裂样式是近期发生的特大地震中结构最复杂的一次逆断层型地表破裂,地表破裂的长度也最长。利用已有的石油地震剖面,结合余震分布和地表破裂带特征等资料构建的三维发震构造模型表明,龙门山推覆构造带现今和第四纪时期以地壳缩短为主,斜滑逆冲型地震表明青藏高原中东部的水平运动在华南地块与巴颜喀拉地块之间的龙门山推覆构造带上转化为地壳的缩短和隆升     

MAP PREPARATION OF EARTHQUAKE SURFACE RUPTURES IN THE NATIONAL EXPERIMENTAL FIELD OF EARTHQUAKE MONITORING AND PREDICTION IN SICHUAN AND YUNNAN PROVINCE

To establish an experimental, practical and open scientific experimental platform for earthquake monitoring and prediction, with reference to that of the southern California earthquake center(SCEC), China Earthquake Administration initiated a project for an experimental field in Sichuan and Yunnan Province in 2014. The chosen area is a seismically active region in the southeastern margin of the Tibetan plateau. A series of work compiling basic maps have been launched to collect fundamental data of this area including geologic structure, earthquake geology, geophysics, geodesy, and geochemistry. The map of earthquake surface ruptures in this region is one of these basic maps. This paper presents the compilation of this map. It includes earthquake epicenters, earthquake surface ruptures, faults, strata, magmatic rocks, and geographical data. This work summarized 87 destructive earthquakes, and 22 earthquake surface rupture zones, and analyzed the distribution characterization of earthquake epicenters, strata and magmatic rocks. The content in the map is reliable and integrated. This work will provide reliable earthquake-geology data for establishing geodynamics models and other future research of the national experimental field of earthquake monitoring and prediction in Sichuan and Yunnan Province.     

汶川M_s 8.0地震中央断裂东北端地表破裂特征及其构造含义

汶川地震地表破裂在东北端从石坎子乡到窝前的运动性质存着从走滑分量略高于倾滑分量到完全为右旋走滑运动的变化过程,倾滑分量在石坎子—平溪段具有逆断性质,在矿坪子及其以北为正断性质,未见挤压变形,窝前完全为右旋走滑运动,地表变形带宽度集中在10m以内;在董家村,地震地表破裂带主要表现为张性裂缝及地堑式负地形,是地震破裂在尾端应力作用下,应变不均一性调节的产物,地表变形带宽度约10～12m;在东河口以北未见地表破裂的证据,推测汶川地震地表破裂带没有穿过流经青川县东河口、关庄、凉水井一带的清水河,东河口一带的构造地貌现象反映了垂直差异性运动,不存在右旋走滑运动的地质地貌证据。在中央断裂东北端断层一侧隆升和另一侧拉张的典型四象限格局成为汶川地震地表破裂的端部表现特征。中央断裂上的汶川地震地表破裂带总长度为240km左右。在汶川地震过程中,沿着中央断裂在地表产生的构造变形在中央断裂的范围内就已经得到了调整,并没有越过中央断裂的范围而传递到以外的地段。     

COSEISMIC SURFACE RUPTURES AND SEISMOGENIC MUJI FAULT OF THE 25 NOVEMBER 2016 ARKETAO MW6.6 EARTHQUAKE IN NORTHERN PAMIR

The M_W6.6 Arketao earthquake,which occurred at 14:24:30 UTC 25 November 2016 was the largest earthquake to strike the sparsely inhabited Muji Basin of the Kongur extension system in the eastern Pamir since the M 7 1895 Tashkurgan earthquake.The preliminary field work,sentinel-1A radar interferometry,and relocated hypocenters of earthquake sequences show that the earthquake consists of at least two sub-events and ruptured at least 77km long of the active Muji dextral-slip fault,and the rupture from this right-lateral earthquake propagated mostly unilaterally to the east and up-dip.Tectonic surface rupture with dextral slip of up to 20cm was observed on two tens-meter long segments near the CENC epicenter and 32.6km to the east along the Muji Fault,the later was along a previously existing strand of the Holocene Muji fault scarps.Focal mechanisms are consistent with right-lateral motion along a plane striking 107°,dipping 76° to the south,with a rake of 174°.This plane is compatible with the observed tectonic surface rupture.More than 388 aftershocks were detected and located using a double-difference technique.The mainshock is relocated at the Muji Fault with a depth of 9.3km.The relocated hypocenters of the 2016 Arketao earthquake sequence showed a more than 85km long,less than 8km wide,and 5~13km deep,NWW trending streak of seismicity to the south of the Muji Fault.The focal mechanism and mapping of the surface rupture helped to document the south-dipping fault plane of the mainshock.The listric Muji Fault is outlined by the well-resolved south-dipping streak of seismicity.The 2016 Arketao M_W6.6 and 2015 Murghob M_W7.2 earthquakes highlight the importance role of strike-slip faulting in accommodating both east-west extensional and north-south compressional forces in the Pamir interior,and demonstrate that the present-day stress and deformation patterns in the northern Pamir plateau are dominant by east-west extension in the shallow upper crust.     

PRIMARILY STUDY ON FEATURES OF SURFACE RUPTURES INDUCED BY THE 2016 MW7.8 KARKOURA EARTHQUAKE,NEW ZEALAND

The surface ruptures produced by the 2016 M_W7.8 Karkoura earthquake, New Zealand are distributed in a belt with~170km long and~35km wide, trending generally in the NE-SW direction. There are at least 12 faults on which meter-scale displacements are identified and they were formed across two distinct seismotectonic provinces with fundamental different characteristics(Hamling et al., 2017; Litchfield et al., 2017). Although the trending directions of the seismic surface ruptures vary greatly at different locations, the ruptured faults can be generally divided into two groups with the NE to NEE direction and the NNW to N direction, respectively. The faults in the NNW-near NS direction are nearly parallel with 40~50km apart and featured by reverse movement with the maximum displacement of 5~6m. The faults in the NE-NNE direction, with the maximum of 25~30km apart are not continuous and featured by the dextral strike slip with the largest displacement of 10~12m. Even if some faults along the NE-NEE direction are end to end connected, their strikes differ by about 30°. The combination styles of the strike-slip fault surface ruptures along the NE-NEE direction can be merged into 3 categories, including en-echelon, bifurcation and parallel patterns. The scales of the fault surface ruptures with the same structural style could be obviously different in different areas, which results in significant changes in the widths of deformation zone, from tens of meters to hundreds of meters. En-echelon distributed surface rupture(section)can appear as a combination belt of meter-scale to dozens of meter-scale shear fracture with bulge and compressional shear fractures, and also can be characterized by the combination of the left-step en-echelon tensile shear fractures with a length of more than one hundred meters. The step-overs between surface rupture sections are clearly different in sizes, which can be dozens of meters, hundreds of meters to several kilometers. The spacing between parallel surface ruptures can be several meters, dozens of meters to several kilometers. Besides, as one of the prominent characteristics, the seismic surface ruptures caused by the Karkoura earthquake broke through the known distribution pattern of active faults. The surface ruptures can occur either on the previously thought inactive or unmapped faults, or break through the distribution range of previously realized active faults in the striking or lateral direction. The basic features about the distribution and widths of the surface ruptures induced by the 2016 M_W7.8 Karkoura earthquake, New Zealand presented in this paper might be helpful for understanding some seismic problems such as complex corresponding relationship between the active faults and the deep seismogenic structure, and the necessary measurements for engineering crossing active faults.     

龙门山山前疑似汶川M_S 8.0地震地表破裂的浅层地震反射调查

2008年5月12日发生在龙门山构造带的汶川MS8.0大地震是映秀-北川断裂突发错动的结果。此次地震不但使NE向的映秀-北川断裂和灌县-江油断裂发生了地表破裂,而且,在成都平原区的什邡、绵竹等地也出现了不同程度的地表裂缝、公路拱曲以及带状的喷砂冒水现象。此项探测研究以出现在什邡市师古镇附近的疑似地震地表破裂带为切入点,通过采用可控震源以及高精度的浅层地震反射勘探方法,获得了深度15～800m范围内高分辨率的地下结构和构造图像。结果表明,在地表破裂之下存在向平原区逆冲的隐伏断层和反向的逆冲断层,地震过程中隐伏逆断层的活动可能是近地表地层出现褶皱变形和地表破裂的主要原因     

汶川8.0级地震地表破裂带宽度调查

根据汶川8.0级地震地表破裂带的实地调查,龙门山断裂带的中央断裂与前山断裂地表破裂带宽度自北向南一般<40m。在Ⅹ—Ⅺ度极震区,沿断裂延伸方向破裂带之上及其两侧,各类房屋建筑无论何种结构均绝大部分倒塌损毁。考虑到逆断层作用引起的"地壳缩短"以及各种不确定性,并结合以往历史强震地表破裂带的宽度统计,提出汶川8.0级地震灾后重建时,极震区地震断层两侧的"避让带"宽度为25m。在"避让带"之内,只能建造高于抗震设防标准的2层以下的建筑物,应明确禁止兴建学校、医院等公共建筑