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1.
《地震研究进展（英文）》2021,1(2):100027
A remarkable earthquake struck Yutian, China on June 26th, 2020. Here, we use Sentinel-1 images to investigate the deformation induced by this event. We invert the InSAR observations using a two-step approach: a nonlinear inversion to constrain fault geometries with uniform slip based on the rectangular plane dislocation in an elastic half-space, followed by a linear inversion to retrieve the slip distribution on the fault plane. The results show that the maximum LOS displacement is 22.6 cm, and the fault accessed to the ruptured characteristics of normal faults with the minor left-lateral strike-slip component. The fault model indicates a 210° strike. The main rupture zone concentrates in the depth of 5–15 km, and the fault slip peaks at 0.89 m at the depth of 9 km. Then, we calculate the variation of the static Coulomb stress based on the optimal fault model, the results suggest that the Coulomb stress of the Altyn Tagh fault and other neighboring faults has increased and more attention should be paid to possible seismic risks. 相似文献
2.
The characteristics of tectonic stress field about strike slip earthquake－generating structure in the Chinese mainland 总被引：1，自引：0，他引：1
（环文林，汪素云，宋昭仪）Ｔｈｅｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｔｅｃｔｏｎｉｃｓｔｒｅｓｓｆｉｅｌｄａｂｏｕｔｓｔｒｉｋｅｓｌｉｐｅａｒｔｈｑｕａｋｅ－ｇｅｎｅｒａｔｉｎｇｓｔｒｕｃｔｕｒｅｉｎｔｈｅＣｈｉｎｅｓｅｍａｉｎｌａｎｄ￥Ｗｅｎ－Ｌｉｎ... 相似文献
3.
汶川MS8.0级地震的发震构造为龙门山断裂带,地震地表破裂主要分布在其中的北川－映秀断裂和江油－灌县断裂上,尤其是沿前者发育了长达240 km左右的地表破裂带.通过对龙门山断裂带震后断层擦痕的测量,得到311条断层擦痕数据,利用由断层滑动资料反演构造应力张量的计算方法,得到研究区8个测点的构造应力张量数据,并获得了研究区构造应力场特征：区域现代构造应力场以近水平挤压为主,最大主应力方向（σ1）为76°～121°,平均倾角9°,应力结构以逆断型为主.受构造应力场及断层几何特征的影响,地表破裂呈现出分段性：映秀—北川段主要以NW盘逆冲为主,垂直位移明显;北川以北段为逆冲兼走滑,水平位移量与垂直位移量基本相当,或水平位移略大. 相似文献
4.
根据塞积群理论导出了走滑断层两端点固定时位移场随位置的不均匀分布解析表示关系,分析和讨论了断层上不同位置的位移场分布特征, 采用新导出的断层滑动不均匀分布公式对地面的水平位移场和垂直位移场进行了数值模拟计算,并与传统的Okada 位错模型在理论和计算结果上进行了对比分析.理论和计算结果分析表明：断层滑动不均匀分布公式是Okada位错模型在一定条件下理论上的扩展,而Okada位错模型是走滑不均匀公式的零阶近似;断层滑动不均匀分布公式与Okada 位错模型计算的地面位移场在走滑方向、垂直于断层走向和垂直于地面方向的近场变形差异最大在50%至65%之间,而最小差异在1%以内. 相似文献
5.
Shunji Ouchi 《地球表面变化过程与地形》2004,29(2):161-173
Flume experiments, in which the middle section of an erosion channel is displaced horizontally, have been conducted to assess the response of streams to horizontal displacement by a strike‐slip fault. The experimental erosion channel was developed in a mixture of sand and clay, which provided relatively stable banks with its cohesiveness. Horizontal displacement of a strike‐slip fault perpendicular to the channel is expected to add a ?at section to its longitudinal pro?le along the fault line. The experimental stream eliminated this ?at section with downstream degradation, upstream aggradation, and lateral channel shift. As a result, a roughly continuous longitudinal pro?le was maintained. This maintenance of a continuous longitudinal pro?le along channel is considered to be the principle of stream response to horizontal displacement by a strike‐slip fault. Downstream degradation was the dominant process of this stream response in the overall tendency of erosion without sand supply. When the rate of fault displacement was low (long recurrence interval), the experimental stream eroded the fault surface, jutting laterally into the channel like a scarp, and de?ected the channel within the recurrence interval. This lateral channel shift gave some gradient to the reach created by fault displacement (offset reach), and the downstream degradation occurred as much as completing the remaining longitudinal pro?le adjustment. When the rate of fault displacement was high (short recurrence interval), the lateral erosion on the ?rst fault surface was interrupted by the next fault displacement. The displacement was then added incrementally to the existing channel offset making channel shift by lateral erosion increasingly dif?cult. The channel offset with sharp bends persisted without much modi?cation, and downstream degradation and upstream aggradation became evident with the effect of the offset channel course, which worked like a dam. In this case, a slight local convexity, which was incidentally formed by downstream degradation and upstream aggradation, tended to remain in the roughly continuous longitudinal pro?le, as long as the horizontal channel offset persisted. In either case, once the experimental stream obtained a roughly continuous gradient, further channel adjustment seemed to halt. Horizontal channel offset remained to a greater or lesser extent at the end of each run long after the last fault displacement. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
6.
《地震研究进展（英文）》2021,1(4):100032
Slip rate along the major active fault is an important parameter in the quantitative study of active tectonics. It is the average rate of fault slip during a certain period of time, reflecting the rate of strain energy accumulation on the fault zone. It cannot only be directly applied to evaluate the activity of the fault, the probabilistic seismic hazard analysis, but also important basic data for the study of geodynamics. However, due to the nonstandardized process of obtaining fault slip rates for a given strike-slip fault, the results could be diverse based on various methods by different researchers. In this review, we analyzed the main advances in the approaches to obtain fault slip rate. We found that there are four main sources affecting the final results of slip rate: the displacement along the fault, the dating of the corresponding displacement, the fitting of the displacement and corresponding dating results, and paleoslip analysis. The main advances in obtaining fault slip rates are based on improving the reliability of the above four main factors. To obtain a more reasonable and reliable slip rate for a given fault, it is necessary to select a suitable method according to the specific situation. 相似文献
7.
2017年8月8日我国四川九寨沟发生里氏7.0级地震.本研究利用基线校正方法获得距震中100km范围内9个强震台站同震位移,基于Sentinel-1卫星干涉SAR影像对获取了InSAR同震形变场.结合GPS形变数据,本研究进行了震源滑动模型联合反演,结果显示此次地震整体以走滑运动为主,释放地震矩约为7.60×1018 N·m(～MW6.52).通过对比模拟形变场和观测值显示,联合反演结果优于单独基于InSAR形变场的反演结果.静态应力变化计算结果显示断层平均静态应力降为1.07MPa.反演滑动模型沿走向和倾角方向拐角波数值分别为0.99×10-4和1.10×10-4.同震静态库仑应力变化计算结果显示共有83.6%的余震位于库仑应力增加的区域,被主震所触发的余震占总数的77.9%,主震对后续余震具有显著触发作用.强地面运动模拟结果显示模拟结果在烈度分布范围和等级方面与调查烈度符合度很高,模拟结果能够很好地反映断层破裂的方向性效应等特征.本研究计算结果显示九寨沟地震无论是平均静态应力降还是拐角波数均低于同类型地震的平均水平,这可能是造成本次地震强地震动水平相对不高的原因. 相似文献
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2008年5月12日发生在四川汶川的大地震造成映秀—北川断裂和灌县—江油断裂同时破裂,分别形成了240多公里和70多公里的地表破裂带.本文以GPS观测获得的同震位移场为约束,反演地震破裂的空间分布.反演结果显示映秀—北川主破裂带倾向北西,沿破裂带的走向从南到北倾角逐渐变大,破裂断层的平均宽度在10~18 km左右.破裂断层的错动在南段以逆冲为主,在北段走滑分量逐步加大,右旋走滑成为断层破裂的主要特征.断层破裂最大段落错动量分别达到了7.8 m和7.4 m,恰好对应这次地震中地表破坏最为严重的映秀和北川地区.本次地震释放地震矩6.70×1020N·m,相应矩震级Mw=7.9. 相似文献
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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
10.
The Chaman left‐lateral strike‐slip fault bounds the rigid Indian plate boundary at the western end of the Himalayan‐Tibetan orogen and is marked by contrasting topographic relief. Deformed landforms along the fault provide an excellent record for understanding this actively evolving intra‐continental strike‐slip fault. The geomorphic response of an active transpessional stretch of the Chaman fault was studied using digital elevation model (DEM) data integrated with Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Visible and Near Infrared/Short Wave Infrared (VNIR/SWIR) and images from GeoEye‐1. Geologic and geomorphic mapping helped in reconstructing the Late Quaternary landscape history of this transpessional strand of the Chaman strike‐slip fault and the associated Spinatizha thrust fault in western Pakistan. Topographic analysis of a part of the transpression (the thrust bounded Roghani ridge) revealed northward growth of the Spinatizha fault with the presence of three water gaps and two corresponding wind gaps. Geomorphic indices including stream length‐gradient index, mountain front sinuosity, valley floor width to valley height ratios, and entrenchment of recent alluvial fan deposits were used to define the lateral growth and direction of propagation of the Spinatizha fault. Left‐lateral displacement along Chaman fault and uplift along the Spinatizha fault was defined using topographic analysis of the Roghani ridge and geomorphic mapping of an impressive alluvial fan, the Bostankaul fan. The landforms and structures record slip partitioning along the Indian plate boundary, and account for the convergence resulting from the difference in the Chaman fault azimuth and orientation of the velocity vector of the Indian plate. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
11.
利用断层滑动资料反演构造应力张量从而确定出海原、六盘山断裂带至银川断陷的第四纪两期构造应力场 :早更新世末期以前 ,为北东—南西挤压型构造应力场 ,由此造成该地区断裂活动主要以逆断为主 ;早更新世末期至中更新世以后 ,构造应力场发生了调整 ,主压应力方向由早期的北东—南西改变为北东东—南西西 ,应力结构由挤压型转变为走滑型 ,并导致断裂活动由早期的逆断为主变为走滑为主 ,这种应力场格局一直持续至今。研究区现代构造应力场可划分为 :海原断裂带走滑应力区、六盘山逆断 -走滑混合应力区和银川断陷拉张应力区 相似文献
12.
利用川滇地区1991-1999年的高精度GPS观测处理结果,采用稳健 - 贝叶斯最小二乘算法与多断裂位错模型,分析研究了川滇菱形块体主要边界运动的定量模型.反演分析表明:川西鲜水河断裂带和安宁河断裂带的左旋走滑运动速率约30mm/a,倾滑运动(逆断层)速率分别约9-11mm/a;滇西红河断裂带、程海断裂带、鹤庆 - 洱源断裂带的走滑运动(分别为右旋、左旋、左旋)速率分别约、11、13mm/a,倾滑运动(正断层)速率分别约16、24、16mm/a;如将其视为弹性应力应变积累,则各断层每年有相当于6级左右的地震能量积累.依据上述反演结果,模拟了区域主要断层运动引起的水平位移、应变速率场图像,显示了边界断裂及其之间的相互作用. 相似文献
13.
为深入理解汶川地震破裂的构造运动机制,本文选取典型的观测点,利用多种地质地貌标志测绘分析得到了汶川MS8.0地震发震断裂的近地表三维同震滑移矢量.结果显示,北川—映秀断裂上的白水河—高川破裂段北西盘沿88°方位角水平滑移2.58 m、垂直滑移3.70 m;安县—灌县断裂上的白鹿—汉旺破裂北西盘沿134°方位角水平滑移1.63 m,垂直滑移2.00 m;小鱼洞破裂带南西盘沿76°~79°方位角水平滑移2.15~2.71 m,垂直滑移1.36~1.51 m.平行的白水河—高川破裂段和白鹿—汉旺破裂段合计形成1.72 m右旋走滑和3.49 m垂直断裂带的NW向水平缩短,总滑移方向（106°）与断裂带整体走向（42°）呈64°夹角,整个龙门山推覆构造带处于斜向挤压的构造环境.结合震源过程反演成果的分析显示,斜滑的白水河—高川破裂段和逆冲型白鹿—汉旺破裂段可能是在汶川地震中最大的一次子事件过程以滑移分解的形式而同时破裂形成的,滑移分解作用使两条断裂以斜滑与逆冲组合的力学性质产生破裂而非相同性质的斜滑破裂.小鱼洞破裂以低角度斜滑为主,可能是安县—灌县断裂与北川—映秀断裂以滑移分解形式同时破裂的纽带.小鱼洞断裂是龙门山断裂带长期处于斜向挤压的构造环境的产物,不只是逆冲断裂系中的捩断层. 相似文献
14.
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15.
With the more complete acoustic emission (AE) catalog improved by the multi-channel AE matched-filter technique (MFT), we study the spatiotemporal evolution of the AE activities after laboratory stick-slip events incorporate with the slip data recorded by displacement transducers on an ~1.5 m granite fault. The results show that the number of the AE events identified by MFT is about 9 times larger than that of the traditional method. A logarithmic expansion of early AE events along the fault strike is observed as a function of time, whereas the fault does not slip in the same manner. Thus, we related the expansion of the early AE events along the fault to the stress transfer caused by the adjacent AE events. Moreover, there is a good correlation between the cumulative number of the later AE events and the amount of fault slip. It suggests that the stress change caused by the continuous slip of the simulated fault after the stick-slip events response for the later AE events near or on the simulated fault. 相似文献
16.
本文研究了有限长度含有单一粗糙面的垂直走滑断层的滑动弱化不稳定性.我们假定断层强度在其深度方向是均匀的,而在走滑方向是不均匀的,即存在一个高强度段.并假定断层上的粗糙段及断层上的其它部分具有相同类型的本构律,只是峰值应力不同.断层周围的地壳材料用上、下表面应力自由的弹性平板来模拟.我们用有限元方法研究了理论位移场、应力场和应变场随远场位移的演变情况.此时,断层位移和摩擦应力并不是预先给定的,而是在求解过程中同时确定的.根据计算结果,我们比较了理论位移场及断层上摩擦应力分布在稳定和不稳定滑动情况时的差别.并与内部含有低强度段的走滑断层的场合做了比较. 相似文献
17.
Development of faults as zones of deformation bands and as slip surfaces in sandstone 总被引：10，自引：0，他引：10
Three forms of fault are recognized in Entrada and Navajo Sandstones in the San Rafael Desert, southeastern Utah; deformation bands, zones of deformation bands, and slip surfaces. Small faults occur asdeformation bands, about one millimeter thick, in which pores collapse and sand grains fracture, and along which there are shear displacements on the order of a few millimeters or centimeters. Two or more deformation bands adjacent to each other, which share the same average strike and dip, form azone of deformation bands. A zone becomes thicker by addition of new bands, side by side. Displacement across a zone is the sum of displacements on each individual band. The thickest zones are about 0.5 m and total displacement across a thick zone rarely exceeds 30 cm. Finally,slip surfaces, which are through-going surfaces of discontinuity in displacement, form at either edge of zones of highly concentrated deformation bands. In contrast with individual deformation bands and zones of deformation bands, slip surfaces accommodate large displacements, on the order of several meters in the San Rafael Desert.The sequence of development is from individual deformation bands, to zones, to slip surfaces, and each type of faulting apparently is controlled by somewhat different processes. The formation of zones apparently involves strain hardening, whereas the formation of slip surfaces probably involves strain softening of crushed sandstone. 相似文献
18.
19.
本文利用有限差分法对垂直走滑断层和垂直倾滑断层两种剪切破裂源在不同埋深和不同破裂尺度(指垂直于地面方向上断层尺度)情况下的近场理论地震图进行了讨论,并得到了地表不同震中距处的加速度付氏谱。通过对上述两种源所产生的近场效应的对比分析,本文得到了以下初步结果: (1) 在埋深相同,断层面宽度相同的情况下,垂直走滑断层源对近场地表的影响比垂直倾滑断层源大。(2) 在垂直倾滑断层源的埋深、破裂尺度相同的情况下,在地表同一震中距处产生的水平位移要比垂直位移大。(3) 两种破裂源在地表同一震中距处产生的位移的最大振幅随破裂尺度的增大而增大,且近似为线性关系;在极震区内不同震中距处产生的位移的最大振幅随震中距的增大而减小,且随震中距的变化率在减小;在地表不同震中距处产生的加速度的付氏谱的主峰周期随震中距的增大而变长,随破裂的增大,付氏谱中主峰周期也加长,且长周期成份愈多;随着破裂源埋深的增加,地表不同震中距处产生的位移的最大振幅变小,即等震线变疏。(4) 走滑断层源产生的加速度付氏谱的主峰周期比倾滑断层源长。 相似文献
20.
Fault slip rate is one of the most important subjects in active tectonics research, which reveals the activity and seismic potential of a fault. Due to the improvement of dating precision with the development of dating methods, Holocene geological markers, even the young markers of thousands or hundreds of years old, are widely used in fault slip rate calculation. Usually, uncertainties from a single event and erosion of the accumulated offsets are involved in fault slip rate determination. Two types of uncertainties are related to a single event; the first is the time elapsed since the latest (the most recent) event; the second is the period since the formation of the geological marker to the occurrence of the first event. High‐slip‐rate faults are more sensitive to these uncertainties than low‐slip‐rate faults. In this study, we studied quantitatively the effects of a single event on fault slip rate following the three classic earthquake models: the characteristic earthquake, uniform slip and variable slip models. We suggest that the erosion of the accumulated offset–lateral erosion on a strike‐slip fault, should also be considered in fault slip estimation. Therefore, we propose a differential method to obtain a reliable fault slip rate. In the differential method, the slip rate is the ratio of offset differentials and corresponding age differentials between the older and younger terraces along strike‐slip faults. This kind of differential method could avoid the uncertainties from the first and latest events, as well as that from the lateral erosion. By applying the differential method, we got the revised slip rates of ∼5–10 mm/year on the Altyn Tagh and Kunlun faults. These low slip rates could fit previous geodetic and geological fault slip rates and shortening rates as well as the millennial recurrence intervals of strong earthquakes along the major segments of these faults. 相似文献