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1.
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
2.
逆冲型断裂同震地表变形定量分析的几个问题——以汶川M_S8.0地震为例 总被引：18，自引：4，他引：14
2008年5月12日四川汶川发生MS8.0地震,发震断裂在地表形成以逆断为主的破裂变形带。同震地表变形带的定量分析对理解地震的构造行为具有重要意义。文中以汶川地震典型调查点为例探讨了逆断型同震地表破裂变形带测量分析中值得重视并容易误解的几个问题,分析了地貌面标志和线性标志等测量数据与构造变形参数的几何关系,给出了变形参数的求解方法和相互关系。同时,就多观测点的定量数据在区域断裂几何结构变化和运动学分析中的运用进行了讨论 相似文献
3.
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
4.
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 相似文献
5.
LU Ren-qi XU Xi-wei CHEN Li-chun CHEN Gui-hua YAO Qi SUN Jian-bao REN Jun-jie REN Zhi-kun XU Chong WEI Zhan-yu TAN Xi-bin DONG Shao-peng SHI Feng WU Xi-yan 《地震地质》2018,40(1):1-11
On 8 August 8 2017, an MS7.0 earthquake occurred in Jiuzhaigou County, Sichuan Province. Field geological investigations did not find any co-seismic surface rupture in the epicenter area, implying that the seismogenic structure is likely a hidden active fault. Based on the results of the relocated aftershocks, the seismogenic fault was simulated and characterized using the SKUA-GOCAD software. The three-dimensional model of the seismogenic fault was preliminarily constructed, which shows that the main shock of the Jiuzhaigou MS7.0 earthquake occurred at the sharp bending area of the fault surface, similar to the geometry of the active fault that generated several major earthquakes in the Songpan area during 1973-1976. Our study suggests that high seismicity of this area may be closely related to the inhomogeneous geometry of the fault surface. In this work, we collected the historical earthquakes of M ≥ 6.5, and analyzed the geometric and kinematic features of the active faults in the study area. A three-dimensional fault model for the 10 main active faults was constructed, and its limitation in fault modeling was discussed. It could provide evidence for analyzing the seismotectonics of historical earthquakes, exploring the relationships between earthquakes and active faults, and predicting major earthquakes in the future. 相似文献
6.
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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8.
Andrea Bistacchi W. Ashley Griffith Steven A. F. Smith Giulio Di Toro Richard Jones Stefan Nielsen 《Pure and Applied Geophysics》2011,168(12):2345-2363
Fault surface roughness is a principal factor influencing earthquake mechanics, and particularly rupture initiation, propagation, and arrest. However, little data currently exist on fault surfaces at seismogenic depths. Here, we investigate the roughness of slip surfaces from the seismogenic strike-slip Gole Larghe Fault Zone, exhumed from ca. 10 km depth. The fault zone exploited pre-existing joints and is hosted in granitoid rocks of the Adamello batholith (Italian Alps). Individual seismogenic slip surfaces generally show a first phase of cataclasite production, and a second phase with beautifully preserved pseudotachylytes of variable thickness. We determined the geometry of fault traces over almost five orders of magnitude using terrestrial laser-scanning (LIDAR, ca. 500 to <1 m scale), and 3D mosaics of high-resolution rectified digital photographs (10 m to ca. 1 mm scale). LIDAR scans and photomosaics were georeferenced in 3D using a Differential Global Positioning System, allowing detailed multiscale reconstruction of fault traces in Gocad®. The combination of LIDAR and high-resolution photos has the advantage, compared with classical LIDAR-only surveys, that the spatial resolution of rectified photographs can be very high (up to 0.2 mm/pixel in this study), allowing for detailed outcrop characterization. Fourier power spectrum analysis of the fault traces revealed a self-affine behaviour over 3–5 orders of magnitude, with Hurst exponents ranging between 0.6 and 0.8. Parameters from Fourier analysis have been used to reconstruct synthetic 3D fault surfaces with an equivalent roughness by means of 2D Fourier synthesis. Roughness of pre-existing joints is in a typical range for this kind of structure. Roughness of faults at small scale (1 m to 1 mm) shows a clear genetic relationship with the roughness of precursor joints, and some anisotropy in the self-affine Hurst exponent. Roughness of faults at scales larger than net slip (>1–10 m) is not anisotropic and less evolved than at smaller scales. These observations are consistent with an evolution of roughness, due to fault surface processes, that takes place only at scales smaller or comparable to the observed net slip. Differences in roughness evolution between shallow and deeper faults, the latter showing evidences of seismic activity, are interpreted as the result of different weakening versus induration processes, which also result in localization versus delocalization of deformation in the fault zone. From a methodological point of view, the technique used here is advantageous over direct measurements of exposed fault surfaces in that it preserves, in cross-section, all of the structures which contribute to fault roughness, and removes any subjectivity introduced by the need to distinguish roughness of original slip surfaces from roughness induced by secondary weathering processes. Moreover, offsets can be measured by means of suitable markers and fault rocks are preserved, hence their thickness, composition and structural features can be characterised, providing an integrated dataset which sheds new light on mechanisms of roughness evolution with slip and concomitant fault rock production. 相似文献
9.
5.12汶川地震同震地表破裂带在虹口八角-深溪沟一带主要出露于三叠系须家河组的炭质泥岩中,同震断层泥在颜色、结构上与老断层泥和围岩类似。通过开挖探槽,系统采样,采用粉晶X射线衍射定量分析方法,研究了同震地表破裂带的围岩、断层角砾岩、老断层泥和新断层泥的矿物成分特征。同震断层泥的主要成分为石英和黏土矿物,含微量长石和白云石;断层泥的显著特征为高黏土矿物含量,从同震断层泥、老断层泥、角砾岩到围岩黏土矿物含量依次降低,黏土矿物以伊利石和伊蒙混层为主,含微量绿泥石和高岭石,矿物组成明显比地表破裂带北段同震断层泥简单。不同颜色的同震断层泥成分略有不同,黑色断层泥中伊利石含量明显高于白色断层泥;老断层泥中含有方解石和白云石,而同震断层泥不含方解石,只含微量白云石。同震断层泥中伊蒙混层高含量表明,在本次地震错动中有富含K的流体参与。 相似文献
10.
针对汶川地震PALSAR观测的方位向形变场存在严重电离层影响,导致准确提取断层地表破裂线困难的问题,本文使用一种基于频率域的电离层影响校正方法,从方位向形变场频域数据中提取电离层信号对应的频域信息,通过建模获得空间域电离层信号,并与原始形变场进行差分运算完成电离层影响的校正,还原了汶川地震断层近场沿SAR方位向的真实地表形变场.以校正后的方位向形变场作为数据源,采用非极大值抑制二维梯度算法,准确提取汶川地震北川—映秀断层和灌县—江油断层的地表破裂线.为验证提取结果的可靠性,引入野外地质调查数据进行对比分析,定量计算两条破裂线间的距离差异,结果表明基于SAR形变场自动提取的断层破裂线与野外地质调查数据具有较高的一致性,利用SAR观测形变场可作为调查地震断层地表破裂的重要补充手段. 相似文献
11.
由于对第四纪地层的严重依赖,传统古地震探槽研究方法在基岩区难以发挥作用,导致无法获取基岩区断层的强震活动历史。本研究以山西地堑系的交城断裂为目标断裂,以断裂北段2处基岩断层面为研究对象,通过三维激光扫描技术获取基岩断层面高精度形貌,基于变差函数法结合滑动窗口操作量化断层表面形貌特征,开展在基岩区提取断裂古地震信息的实例研究。结果显示,2处基岩断层面的形貌在高度上具有明显的分段特征,指示了断层面在地震事件作用下的分段出露过程。这种断层面形貌分段特征可以用来识别古地震事件和同震位移量。在思西村基岩断层面上,识别出由老到新的3次古地震事件,同震倾滑位移量依次为2.0 m、1.9 m和2.3 m,在上兰镇基岩断层面上,识别出由老到新的3次古地震事件,同震倾滑位移量依次为1.4 m、2.5 m和2.0 m,指示了交城断裂北、中段具有产生同震位移量大于2 m、震级大于7.5级的破裂型地震的能力。上述研究成果表明,基于三维激光扫描和形貌量化分析方法开展基岩断层面古地震研究,可以准确而高效地识别古地震事件次数和同震位移量,扩展古地震的研究对象,拓宽古地震的研究空间。在未来的研究中,可以适时地开展宇宙成因核素测年以测定断层面的暴露年龄,获得发震年代,给予地震序列年龄框架。 相似文献
12.
Jie Gan Jun Hu Zhiwei Li Changjiang Yang Jihong Liu Qian Sun Wanji Zheng 《中国科学:地球科学(英文版)》2018,61(10):1451-1466
Three-dimensional (3D) co-seismic surface deformations are of great importance to interpret the characteristics of coseismic deformations and to understand the geometries and dynamics of seismogenic faults. In this paper, we propose a method for mapping 3D co-seismic deformations based on InSAR observations and crustal strain characteristics. In addition, the search strategy of correlation points is optimized by adaptive correlation distance, which greatly improves the applicability of the proposed method in restoring deformations in decorrelation areas. Results of the simulation experiment reveal that the proposed method is superior to conventional methods in both the accuracy and completeness. The proposed method is then applied to map the 3D co-seismic surface deformations associated with the 2015 MW7.2 Murghab earthquake using ascending and descending ALOS-2 PALSAR-2 images. The results show that the seismogenic fault is the Sarez-Karakul fault (SKF), which is dominated by NE-SW strike slips with an almost vertical dip angle. The north section and the south segment near the epicentre have obvious subsidence along with a southwestward motion in the northwest wall, and the southeast wall has northeast movement and surface uplift trend along the fault zone. The strain field of the earthquake is also obtained by the proposed method. It is found that the crustal block of the seismic area is obviously affected by dilatation and shear forces, which is in good agreement with the movement character of the sinistral slip. 相似文献
13.
PRIMARILY STUDY ON FEATURES OF SURFACE RUPTURES INDUCED BY THE 2016 MW7.8 KARKOURA EARTHQUAKE,NEW ZEALAND 下载免费PDF全文
下载免费PDF全文 HAN Zhu-jun Nicola Litchfield RAN Hong-liu YUAN Ren-mao GUO Peng Robert M Langridge Russ J Van Dissen 《地震地质》2017,39(4):675-688
The surface ruptures produced by the 2016 MW7.8 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 MW7.8 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. 相似文献
14.
针对2010年4月14日玉树发生MS7.1地震,本文利用InSAR数据给出同震视线向位移确定出的发震断层空间展布,并以该同震位移为约束反演得到主震和最大余震的同震位错分布.结果表明,主震同震位错发生在东玉树断裂,最大余震同震位错发生在西玉树断裂东端;基于位错分布计算了同震库仑应力变化与西部余震集中区地震活动之间的关系,结果反映玉树主震后最为活跃的余震活动可能受控于近东西向的次级断层(走向约为85°),而非玉树主干断裂;玉树断裂带整体呈现为左旋走滑运动,但其具体断层运动形式表现出主干断裂典型走滑运动、走滑断裂间的拉张和逆冲性质的次级运动、次级断裂与主干断裂相互作用下更为复杂的多方向次级断层活动等等不同变形特征,而主震同震破裂与余震空间分布均与这些不同断层变形方式有着密切关系. 相似文献
15.
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
16.
Similarities between strike-slip faults at different scales and a simple age determining method for active faults 总被引：1，自引：0，他引：1
Abstract Several differently scaled strike‐slip faults were examined. The faults shared many geometric features, such as secondary fractures and linkage structures (damage zones). Differences in fault style were not related to specific scale ranges. However, it was recognized that differences in style may occur in different tectonic settings (e.g. dilational/contractional relays or wall/linkage/tip zones), different locations along the master fault or different fault evolution stages. Fractal dimensions were compared for two faults (Gozo and San Andreas), which supports the idea of self‐similarity. Fractal dimensions for traces of faults and fractures of damage zones were higher (D ～1.35) than for the main fault traces (D ～1.005) because of increased complexity due to secondary faults and fractures. Based on the statistical analysis of another fault evolution study, single event movements in earthquake faults typically have a maximum earthquake slip : rupture length ratio of approximately 10?4, although this has only been established for large earthquake faults because of limited data. Most geological faults have a much higher maximum cumulative displacement : fault length ratio; that is, approximately 10?2 to 10?1 (e.g. Gozo, ～10?2; San Andreas, ～10?1). The final cumulative displacement on a fault is produced by accumulation of slip along ruptures. Hence, using the available information from earthquake faults, such as earthquake slip, recurrence interval, maximum cumulative displacement and fault length, the approximate age of active faults can be estimated. The lower limit of estimated active fault age is expressed with maximum cumulative displacement, earthquake slip and recurrence interval as T ? (dmax /u) · I(M). 相似文献
17.
综合利用区域台站和流动台站(近台)的记录,基于初至P震相重新测定了2017年九寨沟序列M_S7.0主震和M_L≥3.0余震的震源位置,并利用较高精度的定位结果分析余震分布与地震构造的关系,解释发震断裂带的结构.获得的新认识有:(1)九寨沟主震震源深度为16km,位于余震带中段的南缘;余震主要分布深度为4～17km.(2)沿余震带的走向,余震分布与主震同震位错大小的分布明显相关.余震带中段8～16km深度存在的余震稀疏区与同震位错的高值区相吻合,应是发震断裂带主凹凸体的部位,也是主震时应变释放较充分的部位;余震带南东段10～18km深度的余震密集区对应了同震位错的亏损区之一,三次M_L≥5.0余震都发生于此;余震带西北段在5～10km之下既缺少余震,又属同震位错的亏损区,可能与那里多条断裂的交汇或合并造成的构造复杂性有关;余震带中-北西段3～5km深度的也缺少余震,也对应了浅部的同震位错亏损区.(3)证实了九寨沟地震的发震构造为虎牙断裂带北段,同时新揭示出发震断裂带表现为由主断裂和分支断裂构成的、向上分叉的花状结构,尺度约为4.5km宽(最大)、35km长,主断裂朝SW陡倾.这些反映主震破裂可能不只受控于单一的断裂,而有可能是沿主断裂发生主破裂,而沿分支断裂发生次要破裂.另外,本文对发震断裂带结构的分段解释,是遵循构造地质学原理去综合震源排列、震源机制解、地表断层已知位置、相邻剖面断层解释结果等信息的分析结果,而不仅仅依据余震的密集分布进行推断. 相似文献
18.
由五条左旋走滑的主要分支断层组成的鲜水河全新世断裂带,以惠远寺拉分区为界,可分为结构特征不同的两段:北西段结构较为简单;南东段则表现了由若干分支断层组成的复杂结构.这种断裂结构的分段性,造成了历史强震活动性的分段差异,同时也可能是断层近代滑动速率空间变化的主要原因. 该断裂带主要的几何特征之一是具有多重羽列性质.本文按阶区尺度的相对大小,作了羽列级别划分.其中,A级羽列不连续区伴有明显的地貌效应,是该断裂带分段的界限,其对历史上7级左右地震的破裂具有较明显的终止作用;B,C两级羽列不连续区也有一定程度的地貌显示,但对历史上大地震的破裂不具有明显的终止作用;更低级别的羽列几何则是在第四纪盖层中发育的地震地裂缝的主要组合型式. 另一种重要的几何特征是断层弯曲.无论沿整个断裂带还是在一些断层段上,均存在着不同程度的走向弯曲.局部弯曲的结果,可能是造成一些大地震时不对称破裂扩展和烈度衰减的重要几何影响因素,同时也可能是大地震或强震原地重复的构造条件之一.文中最后分析和讨论了两次历史大地震发震断层的立体模型. 相似文献
19.
Aiming Lin 《Journal of Seismology》2017,21(5):1079-1100
Field investigations and analyses of satellite images and aerial photographs reveal that the 2016 M w 7.1 (Mj 7.3) Kumamoto earthquake produced a ～40-km surface rupture zone striking NE-SW on central Kyushu Island, Japan. Coseismic surface ruptures were characterized by shear faults, extensional cracks, and mole tracks, which mostly occurred along the pre-existing NE-SW-striking Hinagu–Futagawa fault zone in the southwest and central segments, and newly identified faults in the northeast segment. This study shows that (i) the Hinagu–Futagawa fault zone triggered the 2016 Kumamoto earthquake and controlled the spatial distribution of coseismic surface ruptures; (ii) the southwest and central segments were dominated by right-lateral strike-slip movement with a maximum in-site measured displacement of up to 2.5 m, accompanied by a minor vertical component. In contrast, the northeast segment was dominated by normal faulting with a maximum vertical offset of up to 1.75 m with a minor horizontal component that formed graben structures inside Aso caldera; (iii) coseismic rupturing initiated at the jog area between the Hinagu and Futagawa faults, then propagated northeastward into Aso caldera, where it terminated. The 2016 M w 7.1 Kumamoto earthquake therefore offers a rare opportunity to study the relationships between coseismic rupture processes and pre-existing active faults, as well as the seismotectonics of Aso volcano. 相似文献
20.
根据管道性能设计的理念,现行管道抗震设计规范规定现行输油气管道重要区段和一般区段的设防断层位移分别为预测的最大位移值和平均位移值,目前的断层位移估计方法一般给出的只是断层未来一百年的最大位移值,而不能给出平均位移值。针对此问题,本文综合国内外发震断层在地表的同震位错分布调查结果,总结分析了断层同震位错沿断层地表破裂走向的分布形态特点,并通过对实际震例中不同计算方法得到的平均位移进行对比分析,得到了断层的平均同震位错量与断层最大同震位错量的比值关系。基于国内外地震断层位移的大量数据,考虑一定的安全系数,本文建议采用预测断层最大位移值的2/3作为一般区段输油气管道的设防断层位移。 相似文献