共查询到19条相似文献，搜索用时 187 毫秒
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野外调查表明,青海玉树MS7.1地震发生在青藏高原中部甘孜-玉树断裂的玉树段上,在玉树县结古镇至隆宝镇之间产生了一系列包括剪切破裂、张剪切破裂、压剪切破裂、张性破裂及其不连续岩桥区出现的鼓包或陷落坑(拉分盆地)、高寒地区特有的冰裂缝等地表破裂单元,它们斜列组合成整体走向约300°、长约65 km、最大同震左旋位移2.4 m的地表破裂带,具有变形局部化的基本特征.玉树地震地表破裂带整体上可划分为长约15 km的结隆次级地表破裂带和长约31 km的结古次级地表破裂带,两者呈左阶羽列,其间无地表破裂段长约17 km,对应于MW6.4和MW6.9两个次级地震事件.地表破裂类型、基本组合特征等显示出甘孜-玉树断裂两盘块体的运动方式以纯剪切的左旋走滑为主,从一个方面反映了青藏高原物质存在着向东的逃逸和挤出现象. 相似文献
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地震地表破裂带是地震破裂在地表的直接表现,其宽度是活断层“避让带”和工程抗震设防重要的指示参数.无人机等测量手段的发展为获取地表破裂带的高分辨率影像数据、精细测量破裂带宽度、分析破裂带宽度空间分布特征以及限定合理的活断层“避让带”提供了有利条件.2022年门源MS6.9地震在青藏高原东北缘冷龙岭与托莱山断裂阶区部位产生了显著的左旋走滑型地表破裂带.基于震后获取的高精度无人机正射影像和数字高程模型,文中在门源地震地表破裂带全段精细解译的基础上,沿走向间隔100 m测量了251个宽度数据,R1破裂带最大宽度为209.78±14 m,平均宽度为42 m, R2破裂带最大宽度为115.31±15.72 m,平均宽度为26.14 m.宽度沿走向具有差异性,这主要受控于同震变形强度、破裂带几何结构以及地表第四系松散层发育状况;具体表现为同震位移量大、阶区等复杂几何结构以及穿过第四系松散层区段的破裂带比同震位移量小、平直段以及基岩区段的破裂带要宽.通过对去除离散值后的破裂带宽度数据统计分析,计算出95.4%和68.2%置信区间的有效宽度分别是70或50 m.在工程抗震设防中,若... 相似文献
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从两个地表破裂点的几何学与运动学特征分析汶川地震的破裂方式 总被引：7，自引：0，他引：7
汶川MS8.0地震的地表破裂出现在中央和前山2条断裂上,分别形成了235km和72km长的地震地表破裂带,而且地表破裂表现出复杂的几何学和运动学特征。文中选取了中央断裂上虹口乡桐麻坎和擂鼓镇石岩村2个地表破裂点,通过几何学与运动学特征分析其地表破裂方式。桐麻坎的白沙河河床上4条右阶斜列的主破裂西南侧发育了一条反冲断层坎,精细地形测量反映出了破裂带内的断块特征与破裂过程中的地表掀斜;擂鼓镇石岩村逆冲破裂前缘的2条次级断层形成叠瓦式结构,地貌上表现为挠曲和其上部的地震鼓包。该两点地表破裂的几何学、运动学特征分析表明,本次地震在龙门山中央断裂上的破裂方式以逆冲为主,兼有右旋走滑。这一结果与美国地质调查局、哈佛大学和中国地震台网中心提供的震源机制解基本一致。此外,桐麻坎和石岩村横切破裂带的地形剖面显示出不同的地表掀斜方向,这种不一致主要由于前者位于断裂挠曲后缘,后者位于断裂挠曲前缘 相似文献
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论述了断层地表永久位移概率地震危险性分析方法的发展过程和应用现状，指出了断层地表破裂预测模型研究的意义。根据我国最近的活动断层地表破裂震后调查结果，基于走滑型断层地表破裂数据，拟合了地表破裂预测模型。采用地震活动性模型和地表破裂预测模型，计算了则木河断裂地表迹线上的永久位移危险性曲线，对预测模型在工程场地地震危险性分析中的应用，提出了建议。 相似文献
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同震地表破裂带的空间展布及形变特征是地球深部断层活动在地表的直观地貌表现,不但记录着地震破裂和断层运动的信息,还反映了区域应力和地壳运动状况.因此,开展震后地震地表破裂带调查对于了解发震断层的构造活动尤为重要.高精度地形观测技术可以获取前所未有的高时空分辨率的地球表面特征,为辨别历史地震地表破裂遗迹、提取地表同震位移、活动构造地质填图等提供高质量数据.文中选取富蕴1931年地震地表破裂带作为研究区,利用SfM(Structural from Motion)摄影测量技术生成分辨率为1 m的数字高程模型(DEM),详细识别地表破裂并测量冲沟的右旋位移.基于地表破裂的几何及构造地貌特征,将富蕴地震地表破裂带由北向南分为S1、S2、S3、S44段,其间以挤压隆起或拉分盆地相连接.沿破裂带共获得194组最新冲沟的右旋水平位移,得到1931年同震位移的平均值为(5.06±0.13)m.同震位移局部缺失或突变的区域与几何阶区的位置也有良好的对应关系.以上结果填补了对富蕴地震地表破裂精细形态研究的空白,也进一步展示高分辨率的地形数据在活动构造研究中良好的应用价值. 相似文献
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大比例尺地震地表破裂带精细填图是研究强震破裂特征及机理的关键数据,为理解破裂动态过程提供重要的观测约束.青藏高原中西部的强震地表破裂研究因发震地点偏远不易到达而成为薄弱环节.文章利用无人机航拍新技术,详细解译获得了2014年于田Ms7.3地震地表破裂展布图.此次地震在阿尔金断裂西段南硝尔库勒断裂(南段S1)、硝尔库勒断裂(中段S2)以及阿什库勒断裂(北段S3)上分别产生了16、6.9和14.2km的地表破裂.南段平均左旋位错为(52±25)cm,最大为~90cm;北段平均左旋位错为(36±21)cm,最大为~84cm.共统计了5308处裂缝宽度,南段平均宽度为(85±71)cm,最宽可达~700cm;中段平均宽度为(39±21)cm,最宽可达243cm;北段平均宽度为(61±44)cm,最宽可达~340cm.另外,南段平均拉张量为(3.4±2.9)m,最大可达~17m;中段平均拉张量为(4.3±3.6)m,最大为~13m;北段平均拉张量为(1.7±1.6)m,最大为~6m.平均裂缝宽度和拉张量在弯曲和阶区部位均显示衰减的趋势.于田地震和其他全球走滑型地震的地表破裂在弯曲、阶区、断裂分叉等断裂几何复杂部位的宽度大于平直段,表明断裂几何结构对破裂宽度具有明显的控制作用.硝尔库勒与南硝尔库勒断裂锐角相交区域发育的大量裂缝可能指示构造拉张部位对近断裂分布式变形的控制,为地震动态破裂的数值模拟提供了观测约束.于田地震还造成罕见的大量伴生地震震动地表破坏,在地震震动的影响下含水盐层可能触发了缓坡度洪积扇的失稳,形成了密集的滑坡和地堑系.这些分布式变形以及浅表伴生变形是地震破裂扩展过程与断裂几何结构耦合关系的直接响应,并暗示破裂在穿过阶区后可能在阿什库勒断裂上双向扩展. 相似文献
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2010年玉树MW6.9地震发生后,已有学者利用DInSAR技术得到了该次地震的同震形变场,并在此基础上反演了其震源破裂滑动分布。本文以提高玉树地震同震形变场准确度作为出发点,设计了一种新的解缠方式获取相应的同震形变场:首先沿地表同震破裂迹线将InSAR干涉图像分割成上下两部分,然后利用网络流解缠算法对其分别进行相位解缠,最后通过统计重叠部分的相位一致性信息将两部分结果进行拼接。利用震中区GPS同震位移数据对分区解缠结果进行验证。结果表明:相对于整体解缠结果,分区解缠方式得到的最大视线向沉降值由42.6cm增加到48.1cm,所得结果与GPS观测结果更加接近,采用分区解缠方式提高了断层附近形变场的准确性。 相似文献
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对历史记载的公元1738年玉树西北地震的震级及其发震构造目前仍存有争议。卫星影像解译和野外调查发现沿甘孜-玉树断裂当江段分布一条长约75km的左旋走滑地震地表破裂带,其最大同震水平位移约2.1m。综合分析该地表破裂带特征、探槽揭露信息、测年结果以及历史文献记载等资料,认为当江段应为1738年玉树西北地震的发震断层,基于震例类比和经验公式估算该次地震的震级为71/2级。沿甘孜-玉树断裂的历史地震破裂分布显示,玉树段在隆宝镇以西存在近50km长的破裂空段;当江段距1738年地震的离逝时间也可能已经接近其地震复发周期,上述两个段落未来均存在大震危险。 相似文献
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地震地表破裂端部的几何结构与运动学特征研究有助于科学认识断裂的破裂传播与终止过程。夏垫断裂是华北平原区最为重要的隐伏强震构造之一,于1679年发生了三河—平谷M8历史大地震,但其同震地表破裂长度及端部变形特征仍存争议。基于前人研究结果,在野外地质调查的基础上,跨1679年三河—平谷8级地震地表破裂端部布设了2条浅层地震勘探剖面,研究断裂端部的新活动特征。结果显示,断裂端部的最新活动时代为全新世,运动方式以走滑为主兼正断,且呈现出明显的滑动亏损特征。结合同震垂直位移分布等数据,分析认为该次地震的地表破裂仅长10余公里,与8级地震不匹配,其发震构造和机制仍需深入研究。 相似文献
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WANG Ming-ming HE Yu-lin LIU Shao WANG Shi-yuan MA Chao ZHANG Wei JIA Zhao-liang 《地震地质》2018,40(4):738-752
The Ganzi-Yushu Fault, the boundary of Bayan Har active tectonic block, Qiantang active tectonic block and Sichuan-Yunan active tectonic block, is a sinistral strike-slip fault zone with intensive Holocene activity. Thus, the study of activity characteristics and rupture behavior of paleoearthquakes in the late Quaternary on the Ganzi-Yushu Fault is of fundamental importance for understanding the future seismic risk of this fault. The southeast section of Ganzi-Yushu Fault is made up of three segments of Ganzi, Manigange and Dengke, where a MS7.3 earthquake in 1866, a MS7.7 earthquake in 1854 and a MS7.3 in 1896 occurred, respectively. There is still lack of in-depth study on the active features and the cascading rupture possibility of these segments, which hindered the evaluation of seismic risk for the southeast section of Ganzi-Yushu Fault. By the means of field geological survey and micro topography measurement, this paper studied the geological and geomorphological features of the southeast section of the Ganzi-Yushu Fault. The results show that the Ganzi and Dengke segments show obvious extension movement, in addition to the left-lateral movement. For Manigange segment, the characteristics of the movement are mainly left-lateral strike-slip and thrusting, and the maximum vertical displacement of the Holocene strata is greater than 2m. In part areas, the movement is normal faulting, which perhaps relates to the left stepping zone in the local stress environment. Therefore, combining the research results such as the fracture distribution in different motion characteristics, rupture behavior of paleoearthquakes, and the distribution of historical earthquake surface ruptures, we divide the southeast section of Ganzi Yushu Fault into Ganzi, Manigange and Dengke segment, and consider the Yakou and the Dengke Basin as the stepovers and the segments' boundaries. As the small scale of impermanent barriers including Dengke Basin and the ridge near Yakou, of which the width is about 1~2km, they may be broken through in great earthquake rupture in future. A trench was excavated in Zhuqing township to investigate the paleoearthquakes on the Manigange segment, radiocarbon dating was employed and 3 paleoseismic events were revealed in the Zhuqing trench, which are the seismic events occurring respectively at 3875~3455BC, after 775BC, and the latest one that ruptured the surface. Compared with the previous results of paleoseismology in the southeast section of Ganzi-Yushu Fault, it is found that the paleoseismic events in the Manigange segment are obviously different with that in Ganzi segment and Dengke segment. Due to the lack of sufficient data on the southeast section of the Ganzi-Yushu Fault, it still needs further discussion whether the cascade-rupturing between these segments exists. 相似文献
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汶川8.0级地震发震断层的累积地震位错研究 总被引：1，自引：0，他引：1
2008年5月12日,四川省汶川县内发生MS8.0地震。此次地震沿龙门山中央断裂产生1条长达200km的同震地表破裂带。文中选择位于地震地表破裂带北段的南坝镇、凤凰村以及南段的映秀镇这3个地点,以被断层错断的河流阶地为研究对象,对多级阶地面上的地震地表破裂及断层陡坎地貌进行了野外实测工作。经过测量数据的计算和分析,得到了各级阶地上断层陡坎的高度,该值即为该阶地记录的地震断层的累积垂直位错量。若以本次地震的垂直位错量作为古地震位错量的均值,则可计算得到每级阶地累积的地震次数。研究结果表明,各点T1阶地形成以来仅经历过1次事件,即本次地震事件;T2阶地形成以来约经历了5次事件;T3阶地形成以来约经历了9～11次事件;T4阶地形成以来约经历了20次事件。在本文研究的基础上,结合前人的阶地测年数据,则可获得古地震复发间隔的可靠数据 相似文献
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本文首先介绍了无人机摄影测量技术获取数字高程模型（digital elevation model,缩写为DEM）和地貌数据（正射影像）的作业流程,对比分析了三种不同质量密集点云生成的DEM在水平位置和高程上的差异;然后以1709年中卫南M7?大地震的主体地表破裂带为例,提取其上地震断层的垂直位错量和水平位移量。研究结果显示:高质量密集点云生成的DEM分辨率可达厘米级,且处理时间不需太长,其水平位置和高程与另外两种质量密集点云生成的DEM差异均小于0.100 m;基于高质量密集点云可生成6.33 cm/pix分辨率的DEM,提取1709年中卫南地震地表破裂带上地震断层的垂直位错量为（0.704±0.293） m,水平位移量为5.1 m,与前人的研究结果相吻合,因此可以代表该地震的同震位移,这表明无人机摄影测量技术能够获取地震地表破裂带典型场点的高分辨率地形地貌数据,并基于生成的DEM可进一步提取地震断层的定量参数。 相似文献
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2008年汶川M_S8.0地震地表破裂变形定量分析——北川-映秀断裂地表破裂带 总被引：35，自引：14，他引：21
2008年汶川MS8.0地震在北川-映秀断裂产生了长达240km的同震地表破裂。通过详细的测量、基于测量标志与断裂变形的几何关系对数据的分析,给出了观测点的断裂同震地表变形的垂直位移、倾向水平缩短、走向滑动、断层上盘水平运动方向等参数。结果显示,断裂同震变形分布的空间变化很大,目前获得的最大水平位移位于虹口乡深溪沟,为4.98m,同时也是最大右旋走滑位移点,走滑量4.5m,而目前获得的最大垂直位移在其东北的支沟,为5.7~6.7m。NE向断裂水平位移多为1~2m,垂直位移多为3m左右,而小鱼洞-草坝分支断裂水平位移和垂直位移都更小,只有0.5~1.5m。擂鼓镇附近的数据则反映与断裂相关的巨型滑坡可能将重力变形叠加到构造变形中。由断层水平缩短和垂直位移计算的断层倾角表明,北川-映秀断裂是浅部陡倾的具有走滑分量的逆断层 相似文献
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青海玉树M_S7.1级地震地表破裂带的遥感影像解译 总被引：1，自引：1，他引：0
2010年4月14日青海省玉树发生MS7.1级地震,造成严重的人员伤亡和重大的经济损失。除组织现场快速震害评估和地表破裂带调查外,利用高分辨率卫星影像解译是迅速给出初步震害评估和同震地表破裂的位置和展布的最佳途径。本文通过对震前、震后高分辨率SPOT卫星影像的对比,解译出了12km长的同震地表破裂带,其在影像上主要表现为线性阴影和色彩变化。地表破裂带位置和先存的断层、老破裂带位置一致,说明青海玉树地震属于原地复发型地震。同时,解译结果也得到了来自野外实地调查结果的验证,证明了遥感解译的可信性和及时性。但解译破裂长度远小于实际破裂长度,也说明了基于2.5m分辨率的SPOT卫星影像的遥感解译存在较大的局限性。 相似文献
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THE CORRELATION BETWEEN GEOMETRIC FEATURE OF CO-SEISMIC RUPTURE AND CO-SEISMIC DISPLACEMENT 
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下载免费PDF全文 The existence of asperity has been confirmed by heterogeneously distributed seismic activities along the slipping surface associated with recent huge earthquakes, such as the M8.0 2008 Wenchuan earthquake and M9.0 2011 Tohoku-Oki earthquake. The location of asperity embedded in the seismogenic depth always corresponds to the area of high value of the co-seismic displacement and stress drop where the elastic energy is accumulated during the inter-seismic periods. Fault segmentation is an essential step for seismic hazard assessment. So far, the fault trace is dominantly segmented by considering its geometric features, such as bends and steps. But the connection between the asperity and geometric feature of the slipping surface is under dispute. Research on correlation between geometric feature of surface rupture and co-seismic displacement is of great significance to understand the relationship of seismicity distribution to geometric morphology of sliding surface. To scrutinize the correlation between the geometric feature and co-seismic displacement, we compiled 28 earthquake cases among which there are 19 strike-slip events and 9 dip-slip events. These cases are mainly collected from the published investigation reports and research papers after the earthquake occurred. All the earthquakes' magnitude is between MW5.4~8.1 except for the MW5.4 Ernablla earthquake. The range of the rupture length lies between 4.5~426km. Each case contains surface rupture trace mapped in detail with corresponding distribution of co-seismic displacement, but the rupture maps vary in projected coordinate system. So, in order to obtain uniform vector graphics for the following data processing, firstly, vectorization of the surface rupture traces associated with each case should be conducted, and secondly, the vector graphics are transformed into identical geographic coordinate system, i.e. WGS1984-UTM projected coordinate system, and detrended to adjust its fitted trend line into horizontal orientation. The geometric features of surface rupture trace are characterized from three aspects, i.e. strike change, step and roughness. Previous studies about the rupture geometry always describe the characteristics from the whole trace length, consequently, the interior change of the geometric characteristics of the rupture is overlooked. In order to solve this problem, a technique of moving window with a specified window size and moving step is performed to quantify the change of feature values along the fault strike. The selected window size would directly affect the quantified result of the geometric feature. There are two contrary effects, large window size would neglect the detail characteristics of the trace, and small window size would split the continuity of the target object and increase the noise component. So we tested a set of sizes on the Gobi-Altay case to select a proper value and choose 1/25 of the whole rupture length as a proper scaling. Here, we utilize the included angle value of the fitted line in the adjoining windows, Coefficient of variation and the intercept value of the PSD(Power Spectra Density)for characterizing the change of strike, step size and roughness. The rupture trace is extracted within every moving window to calculate the aforementioned feature values. Then we can obtain three sets of data from every rupture trace. The co-seismic displacement is averaged in piecewise with uniform interval and moving step along the fault strike. Then, the correlations between three kinds of feature value and the co-seismic displacement are calculated respectively, as well as the P-value of correlation coefficient significant test.
We divided cases into two groups according to the slip mode, i.e. strike-slip group and dip-slip group, and contrast their results. In the correlation result list, there is an apparent discrepancy in correlation values between the two groups. The values of the strike-slip group mostly show negative, which indicates that geometric feature of the rupture trace is in inverse proportion to the displacement. In dip-slip group, the values distribute around zero, which suggests the geometric features is irrelevant to the displacement. Through the analysis of the correlation between the surface rupture and co-seismic displacement, the following conclusions can be reached:1)In comparison with the dip-slip earthquake type, the characteristics of surface rupture of strike-slip earthquakes have a higher-level of correlation with the distribution of the co-seismic displacement, which suggests that the geometric features of strike-slip active faults may have a higher reference value in the fault-segmentation research than the dip-slip type; 2)In most strike-slip events, there is a negative correlation between the geometric features and the co-seismic displacement, which implicates that the higher the feature values of the steps, strike change and roughness, the lower the corresponding co-seismic displacement is; 3)Among the three quantified features of the surface rupture trace, the ranking of relevancy between them and the co-seismic displacement is:step size > strike change > roughness. 相似文献
19.
The Hongyapu M7 1/4 earthquake in 1609 occurred on the Fodongmiao-Hongyazi fault, which is a Holocene active thrust in the middle segment of the northern Qilianshan overthrust fault zone, located in the north-eastern edge of the Tibet plateau. This earthquake caused death of more than 840 people, ruined the Hongyapu Village and had an affected area ca. 200km2. Previous work provided different opinions on the length of the earthquake surface rupture zone, such as 60km from the Bailanghe western riverbank to the Fenglehe eastern river bank, and only 11km from the Hongyazi village to eastern edge of the Hujiatai anticline. And the surface rupture zone appears in the western and middle segments of the Fodongmiao-Hongyazi fault zone.
Our detailed geomorphic analysis and topographic survey found that the surface rupture zone with a total length of ca 95km is present on the new geomorphic surfaces which are slightly higher than the modern allvial-dilvial fans and riverbeds, which begins from the Hongshuiba river, Jiuquan in the west extending to the Toudaodongwan, southern Gansu in the east along the Fodongmiao-Hongyazi Fault. The surface rupture zone occurred later than 0 A D, proved by the study of trenchs and chronology. Compared to the previous research on the epicenters of the historical major earthquakes in and around the study region, this surface rupture zone is considereded to be the surface rupture zone of the Hongyapu earthquake of 1609 in Gansu provice.
Average vertical co-seismic displacement of the 1609 Hongyapu earthquake is 1.1m with maximum 1.8m, dominated by thrusting. The NNW striking Xiaoqun segment shows thrust with a component of dextral strike slip and the NEE-trending East Hongshancun segment is also mainly thrust but with sinistral strike slipp. The lateral movement could be caused by the local change of the fault strike direction.
Based on the length of surface ruptures, the maximum coseismic displacement and fault dipping, this event is estimated to be of ca. MW7.0~MW7.4, close to the M7 1/4 suggested by previous studies. 相似文献