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2017年四川九寨沟MS7.0地震是继2008年汶川MS8.0地震和2013年芦山MS7.0地震之后，青藏高原东缘在不到十年的时间内发生的第三个震级MS7.0以上的强震.这次地震发生在东昆仑断裂带东端，作为青藏高原东北缘的一条大型左旋走滑断裂带，东昆仑断裂带与东端其它构造之间的转换关系仍不清楚，因区内地质构造和地形复杂，东昆仑断裂带东端的主要构造仍缺少深入的研究.本文在总结区域地震构造活动特征、历史地震和现代地震基础上，通过东昆仑断裂带东端已有的和最近开展的活动构造定量研究结果，并结合现今GPS变形场资料和2017年九寨沟MS7.0地震灾害特征分析，发现东昆仑断裂带最东段塔藏断裂上的左旋走滑除了一小部分继续向东传播转移到文县断裂带上外，大部分转化为其南侧的龙日坝断裂带北段、岷江断裂和虎牙断裂上的近东西向地壳缩短，这可能是岷山隆起的构造机制，而2017年九寨沟MS7.0地震正是左旋走滑的东昆仑断裂带在东端继续向东扩展的结果. 相似文献
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东昆仑断裂带东段玛曲断裂古地震初步研究 总被引：10，自引：0，他引：10
东昆仑活动断裂是青藏高原东北部一条重要的NWW向边界断裂。玛曲断裂位于东昆仑断裂带的最东段。本文通过3个古地震剖面揭示出东昆仑断裂东段玛曲断裂全新世共有4次古地震事件。最新一次古地震事件为距今(1730±50)～(1802±52)a,第二次古地震的时间为距今(3736±57)～(4641±60)a;第三次为距今(8590±70)a;第四次为距今(12200±1700)a。其中第一次和第二次古地震事件的时间较为可靠,两次古地震事件之间的复发间隔为2400a左右,由此认为东昆仑断裂带东段的古震事件之间的复发间隔为2400a左右,古地震的离逝时间为距今(1730±50)～(1802±52)a。 相似文献
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2013年甘肃岷县漳县6.6级地震震害分布特征及发震构造分析 总被引：1，自引：0，他引：1
2013年7月22日,甘肃岷县漳县MS6.6地震发生在南北地震带的中北段,东昆仑断裂和西秦岭北缘断裂是该地区复杂多样的构造几何特征中2条主要的边界控制断裂.这次地震的震害分布与临潭-宕昌断裂的走向基本一致,为长轴走向NWW的椭圆,极震区内严重破坏范围也完全位于该断裂带内,这与临潭-宕昌断裂复杂的几何结构密切相关,也说明地震的发生是多条次级断裂共同作用的结果.综合分析认为,受西秦岭北缘断裂带向南侧的扩展和青藏高原向NE扩展过程中东昆仑断裂带的NE向挤压作用共同影响下的临潭-宕昌断裂是这次地震的发震构造. 相似文献
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东昆仑断裂带是青藏高原东北部一条重要的活动断裂, 构成了巴颜喀拉块体的北边界。 根据阿尼玛卿山两侧滑动速率和历史地震的差异, 将断裂带分为东西两个部分。 滑动速率由西向东递减, 近百年的历史地震产生的破裂基本覆盖了西部和东部的一部分。 随着巴颜喀拉块体周缘强震的持续发生, 作为块体北边界的东昆仑断裂带的地震空区及地震潜势研究变得更加重要。 近些年通过对东昆仑断裂带不同段的研究得到了较多的滑动速率和古地震序列数据, 为评价断裂带未来百年地震危险性提供了有利条件。 利用NB模型中的对数正态分布方法, 得到了东昆仑断裂带在未来100 a的发震概率, 研究表明, 东部(玛曲段)发震概率相对较高, 需要进一步关注。 相似文献
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为了解东昆仑断裂活动对2017年8月8日九寨沟MS7.0地震的影响，本文选取1999-2007年、2013-2017年GPS速度场作为约束，基于块体-位错模型反演计算东昆仑断裂两个时间段的块体运动速率、断裂滑动速率和滑动亏损率，并进一步研究青藏高原东缘最大剪应变率场和九寨沟震区的震间库仑应力累积速率.结果显示，东昆仑断裂中西段左旋走滑速率较高，东段走滑速率较低，自西向东逐步递减，存在明显的梯度.在两个时间段，阿坝块体刚性运动的方向顺时针偏转0.2°，运动速率由12.22 mm·a-1增大到15.96 mm·a-1；东昆仑断裂左旋走滑速率升高，其中西段较为明显（升高约1.2±0.3 mm·a-1）；东昆仑断裂东段闭锁深度和闭锁程度增加；2013-2017年，东昆仑断裂滑动引起的九寨沟震区库仑应力累积速率是1999-2007年的3倍，最大剪应变率也明显升高.因此本文认为：2008年汶川地震和2013年芦山地震后，龙门山断裂部分解锁，阿坝地块活动性增强，东昆仑断裂滑动速率增大，导致九寨沟震区库仑应力加载速率增加，加速了九寨沟地震的孕育过程. 相似文献
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《地震地质》2021,43(3)
青藏高原东北缘地区的构造变形以NE向挤压缩短、顺时针旋转和向E挤出为主要特征,在NE向挤压作用下形成了NNW向的右旋走滑断裂,进一步将东北缘地区分为多个次级块体。其中,鄂拉山断裂与东昆仑断裂围限形成的柴达木次级块体整体以向NW方向的旋转挤出为主要特征,但处于这2条边界断裂交会部位的柴达木盆地东缘都兰地区的构造变形方式却不清楚。近期在针对都兰地区的野外地质调查中,发现了一条NW走向、长60～70km的右旋走滑断裂带,即夏日哈断裂带。该断裂带位于鄂拉山断裂西侧,由2条近平行的断裂组成,分别为夏日哈断裂和英德尔康断裂。经遥感解译与野外地质调查发现,该断裂线性特征明显,断错了多期冲积扇、河流阶地等晚第四纪地质地貌体,发现了多个断错晚第四纪沉积物的剖面,显示该断裂带为晚更新世—全新世活动断裂。综合分析认为,该断裂与前期发现的近EW走向的热水-桃斯托河全新世左旋走滑断裂,分别在鄂拉山断裂和东昆仑断裂的影响下共同调节柴达木块体端部的挤出旋转变形。同时,该断裂为该区新发现的活动断裂,具有中强地震的潜在发震能力,这不仅对理解区域构造变形模式具有重要意义,也导致对该区域地震危险性的认识发生较大改变。因此,亟待在该区域开展更进一步研究工作,以增进对区域应变分配模式的理解,为区域地震安全问题提供参考。 相似文献
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位于南北地震带中北段的甘东南地区,其构造变形和构造活动特征与青藏高原向北东方向的扩展密切相关,该地区复杂的构造几何形态主要受控于东昆仑断裂和西秦岭北缘断裂,区域新构造运动主要动力来源于青藏高原向北东的扩展.近年来,甘东南地区中强地震频发,本文主要通过对该地区构造活动特征、历史地震等资料的综合分析讨论,结合地球物理、地震学和野外调查等资料,认为青藏高原东北部东昆仑断裂的向北挤压和向东的运动是该地区构造应力集中的主要原因,也是该地区中强地震的主要孕震环境和机制,而西秦岭北缘断裂的走滑及向南北两侧逆冲“花状构造”是临潭—宕昌断裂带上中强地震频繁发生的一个重要动力因素.2013年7月22日发生在甘肃岷县—漳县的MS6.6级地震正好位于临潭—宕昌断裂带中东段上,是该断裂分段不均匀活动的结果. 相似文献
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1937年托索湖7.5级地震发生在东昆仑活动断裂带的东段,前人曾对该地震组织过4次不同程度的考察,并得出了4种不同的结果。带着上述问题对该地震地表破裂带重新进行了实地考察、测量和综合研究,然后对该地震地表破裂带的西端点、最大左旋水平位移量、最大垂直位移量、宏观震中等问题进行了重新厘定,认为1937年托索湖7.5级地震地表破裂带西端点在阿拉克湖以西,长度至少为240km,最大左旋水平位移量为8m,垂直位移量为3.5m,宏观震中在三岔口一带 相似文献
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沿长约 4 2 6km的 2 0 0 1年昆仑山口西MS8 1地震地表破裂带共获得 2 91个点的地表同震水平左旋位移数据 ,并在其中 1 1 1个点获得了垂直位移数据。该地震总体以左旋水平位移为主 ,兼具一定的垂直位移。最大地表左旋水平位移值可达 6 4m ,平均水平位移约为 2 7m ,绝大多数测点的垂直位移均 <1m。地表水平位移沿主破裂带走向位移梯度变化于 1 0 - 1～ 1 0 - 4之间 ,这一起伏变化可能起因于野外测量误差、沿主破裂带岩性或松散沉积物厚度的变化、地表破裂带几何结构的不均匀性、地表破裂走向的变化、不同破裂段在昆仑山口西 8 1级地震之前的地震中滑动量的起伏变化 ,以及大量非脆性变形、次级破裂的存在等。水平位移沿主破裂带的长波长 (数十公里至数百公里 )起伏变化较有规律 ,在布喀达坂峰以东表现为分别以 5个水平位移峰值为中心而有规律地起伏变化。这5个位移峰值分别对应于不同的次级地震地表破裂段。各破裂段水平位移峰值均向阶区或拐点逐渐衰减 ,不同地表破裂段位移峰值向两侧衰减的速率是不同的 ,这种位移梯度的不对称分布可能指示了地震破裂的扩展方向。上述位移分布特征真实地反映了地表可见脆 相似文献
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The November 14, 2001 Ms8.1 Kunlun Mountains earthquake in northern Tibet is the largest earthquake occurring on the Chinese mainland since 1950. We apply a three-dimensional （3-D） finite element numerical procedure to model the coseismic displacement and stress fields of the earthquake based on field investigations. We then further investigate the stress interaction between the Ms8.1 earthquake and the intensive aftershocks. Our primary calculation shows that the coseismic displacement field is centralized around the east Kunlun fault zone. And the attenuation of coseismic displacements on the south side of Kunlun fault zone is larger than that on the north side. The calculated coseismic stress field also indicates that the calculated maximal shear stress field is centralized around the east Kunlun fault zone; the directions of the coseismic major principal stress are opposite to that of the background crustal stress field of the Qinghai-Xizang （Tibet） Plateau. It indicates that the earthquake relaxes the crustal stress state in the Qinghai-Xizang （Tibet） Plateau. Finally, we study the stress interaction between Ms8.1 earthquake and its intensive aftershocks. The calculated Coulomb stress changes of the Ms8.1 great earthquake are in favor of triggering 4 aftershocks. 相似文献
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ELECTRICAL STRUCTURE OF THE 2017 MS7.0 JIUZHAIGOU EARTHQUAKE REGION AND THE EASTERN TERMINUS OF THE EAST KUNLUN FAULT 
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下载免费PDF全文 SUN Xiang-yu ZHAN Yan ZHAO Ling-qiang CHEN Xiao-bin LI Chen-xia SUN Jian-bao HAN Jing CUI Teng-fa 《地震地质》1979,42(1):182-197
The East Kunlun Fault is a giant fault in northern Tibetan, extending eastward and a boundary between the Songpan-Ganzi block and the West Qinling orogenic zone. The East Kunlun Fault branches out into a horsetail structure which is formed by several branch faults. The 2017 Jiuzhaigou MS7.0 earthquake occurred in the horsetail structure of the East Kunlun Fault and caused huge casualties. As one of several major faults that regulate the expansion of the Tibetan plateau, the complexity of the deep extension geometry of the East Kunlun Fault has also attracted a large number of geophysical exploration studies in this area, but only a few are across the Jiuzhaigou earthquake region. Changes in pressure or slip caused by the fluid can cause changes in fault activity. The presence of fluid can cause the conductivity of the rock mass inside the fault zone to increase significantly. MT method is the most sensitive geophysical method to reflect the conductivity of the rock mass. Thus MT is often used to study the segmented structure of active fault zones. In recent years MT exploration has been carried out in several earthquake regions and the results suggest that the location of main shock and aftershocks are controlled by the resistivity structure. In order to study the deep extension characteristics of the East Kunlun Fault and the distribution of the medium properties within the fault zone, we carried out a MT exploration study across the Tazang section of the East Kunlun Fault in 2016. The profile in this study crosses the Jiuzhaigou earthquake region. Other two MT profiles that cross the Maqu section of East Kunlun Fault performed by previous researches are also collected. Phase tensor decomposition is used in this paper to analyze the dimensionality and the change in resistivity with depth. The structure of Songpan-Ganzi block is simple from deep to shallow. The structure of West Qinlin orogenic zone is complex in the east and simple in the west. The structure near the East Kunlun Fault is complex. We use 3D inversion to image the three MT profiles and obtained 3D electrical structure along three profiles. The root-mean-square misfit of inversions is 2.60 and 2.70. Our results reveal that in the tightened northwest part of the horsetail structure, the East Kunlun Fault, the Bailongjiang Fault, and the Guanggaishan-Dieshan Fault are electrical boundaries that dip to the southwest. The three faults combine in the mid-lower crust to form a "flower structure" that expands from south to north. In the southeastward spreading part of the horsetail structure, the north section of the Huya Fault is an electrical boundary that extends deep. The Tazang Fault has obvious smaller scale than the Huya Fault. The Minjiang Fault is an electrical boundary in the upper crust. The Huya Fault and the Tazang Fault form a one-side flower structure. The Bailongjiang and the Guanggaishan-Dieshan Fault form a "flower structure" that expands from south to north too. The two "flower structures" combine in the high conductivity layer of mid-lower crust. In Songpan-Ganzi block, there is a three-layer structure where the second layer is a high conductivity layer. In the West Qinling orogenic zone, there is a similar structure with the Songpan-Ganzi block, but the high conductivity layer in the West Qinling orogenic zone is shallower than the high conductivity layer in the Songpan-Ganzi block. The hypocenter of 2017 MS7.0 Jiuzhaigou earthquake is between the high and low resistivity bodies at the shallow northeastern boundary of the high conductivity layer. The low resistivity body is prone to move and deform. The high resistivity body blocked the movement of low resistivity body. Such a structure and the movement mode cause the uplift near the East Kunlun Fault. The electrical structure and rheological structure of Jiuzhaigou earthquake region suggest that the focal depth of the earthquake is less than 11km. The Huya Fault extends deeper than the Tazang Fault. The seismogenic fault of the 2017 Jiuzhaigou earthquake is the Huya Fault. The high conductivity layer is deep in the southwest and shallow in the northeast, which indicates that the northeast movement of Tibetan plateau is the cause of the 2017 Jiuzhaigou earthquake. 相似文献
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文中以东昆仑断裂带周围分布的27个GPS站点的地壳运动速率矢量为约束,利用半无限弹性空间三维断裂位错模型,反演了东昆仑断裂、柴达木盆地北缘断裂、玛尼-玉树断裂和玛尔盖茶卡断裂带在2001年昆仑山口西MS8.1地震之前的运动速率,并认为这些断裂带以反演出的运动速率错动所形成的形变场可以作为震前的背景地壳形变场。基于这一具有构造意义的背景速度场资料,计算了区域地壳应变率场和地震矩累积率场。结果表明,昆仑山口西地震前,东昆仑断裂的东西大滩段和玛尼-玉树断裂西段为该区域2个最显著的地震矩累积率高值区,其中东昆仑断裂的东西大滩段高值区为后来的昆仑山口西MS8.1地震的发震段 相似文献
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震后野外考察表明 ,2 0 0 1年 11月 14日昆仑山库赛湖地震 (MS8 1)发生在青藏高原北部东昆仑断裂带库赛湖段上 ,发震断层具有高速率左旋滑动的基本特征 ,晚更新世晚期以来的平均滑动速率达 (14 8± 2 4 )mm/a ;地震地表破裂带沿库赛湖段西起布喀达板峰东缘 (91°0 8′E) ,向东经库赛湖北缘、青藏公路 2 894里程碑、玉珠峰南麓 ,东止于青藏公路东 70km附近 (94°4 8′E) ,地震地表破裂带沿N70°～ 90°W走向线状展布 ,全长约 35 0km ,由一系列走向N4 5°～ 5 0°E拉开状张裂缝、走向N6 0°～ 75°E张剪切裂缝、走向N80°W剪切裂缝以及隆起鼓包或开裂陷坑等斜列状组合而成 ,显示出纯剪切走滑的破裂特征 ,最大左旋水平位移 6m ;宏观震中位于昆仑山口西 80～ 90km附近的库赛湖东北角山麓地带 ,地震地表破裂带宽度 30 0m ,在库赛湖北岸至山麓地带的地震地表破裂带和由地震动或重力效应引起的次生破裂带总宽度可达 2km。库赛湖地震地表破裂的左旋走滑特征表明 ,青藏高原物质确实存在着向东的滑移或流动 ,东昆仑断裂带东部与库赛湖段斜列的东大 相似文献
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On August 8, 2017, Beijing time, an earthquake of M7.0 occurred in Jiuzhaigou County, Aba Prefecture, Sichuan Province, with the epicenter located at 33.20°N 103.82°E. The earthquake caused 25 people dead, 525 people injured, 6 people missing and 170000 people affected. Many houses were damaged to various degrees. Up to October 15, 2017, a total of 7679 aftershocks were recorded, including 2099 earthquakes of M ≥ 1.0.
The M7.0 Jiuzhaigou earthquake occurred in the northeastern boundary belt of the Bayan Har block on the Qinghai-Tibet Plateau, where many active faults are developed, including the Tazhong Fault(the eastern segment of the East Kunlun Fault), the Minjiang fault zone, the Xueshan fault zone, the Huya fault zone, the Wenxian fault zone, the Guanggaishan-Daishan Fault, the Bailongjiang Fault, the Longriuba Fault and the Longmenshan Fault. As one of the important passages for the eastward extrusion movement of the Qinghai-Tibet Plateau(Tapponnier et al., 2001), the East Kunlun fault zone has a crucial influence on the tectonic activities of the northeastern boundary belt of Bayan Kala. Meanwhile, the Coulomb stress, fault strain and other research results show that the eastern boundary of the Bayan Har block still has a high risk of strong earthquakes in the future. So the study of the M7.0 Jiuzhaigou earthquake' seismogenic faults and stress fields is of great significance for scientific understanding of the seismogenic environment and geodynamics of the eastern boundary of Bayan Har block.
In this paper, the epicenter of the main shock and its aftershocks were relocated by the double-difference relocation method and the spatial distribution of the aftershock sequence was obtained. Then we determined the focal mechanism solutions of 24 aftershocks(M ≥ 3.0)by using the CAP algorithm with the waveform records of China Digital Seismic Network. After that, we applied the sliding fitting algorithm to invert the stress field of the earthquake area based on the previous results of the mechanism solutions. Combining with the previous research results of seismogeology in this area, we discussed the seismogenic fault structure and dynamic characteristics of the M7.0 Jiuzhaigou earthquake. Our research results indicated that:1)The epicenters of the M7.0 Jiuzhaigou earthquake sequence distribute along NW-SE in a stripe pattern with a long axis of about 35km and a short axis of about 8km, and with high inclination and dipping to the southwest, the focal depths are mainly concentrated in the range of 2~25km, gradually deepening from northwest to southeast along the fault, but the dip angle does not change remarkably on the whole fault. 2)The focal mechanism solution of the M7.0 Jiuzhaigou earthquake is:strike 151°, dip 69° and rake 12° for nodal plane Ⅰ, and 245°, 78° and -158° for nodal plane Ⅱ, the main shock type is pure strike-slip and the centroid depth of the earthquake is about 5km. Most of the focal mechanism of the aftershock sequence is strike-slip type, which is consistent with the main shock's focal mechanism solution; 3)In the earthquake source area, the principal compressive stress and the principal tensile stress are both near horizontal, and the principal compressive stress is near east-west direction, while the principal tensile stress is near north-south direction. The Jiuzhaigou earthquake is a strike-slip event that occurs under the horizontal compressive stress. 相似文献