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欧亚地震带现代构造应力场及其分区特征 总被引：1，自引：0，他引：1
利用美国哈佛大学矩心矩张量目录中的2818个地震的震源机制解资料,分析了欧亚地震带及其5个分区现代构造应力场的基本特征,给出了5个分区的震源机制主压应力方向分布图。结果表明:①欧亚地震带以逆断型和走滑型断层活动为主;②地中海地震区以走滑断层活动为主,主压应力方向为SSW向;③伊朗—阿富汗—巴基斯坦地震区以逆断型断层活动为主,主压应力优势方向为NNE—NS向;④喜马拉雅地震以逆断型为主,主压应力优势方向为NS和NE向;⑤川—滇—缅地震区以走滑断层活动为主,主应力场方向为NNE向;⑥印度尼西亚地震区以逆断型断层活动为主,主压应力优势方向为NE—SSW向。各分区的主压应力方向明显受其所在区域板块运动的影响,由此推测板块运动可能是产生欧亚地震带构造应力的主要力源。 相似文献
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利用1997-1998年伽师强震群中强地震震源机制系统聚类及震源区应力场反演,得到以下主要结果:(1)伽师强震群中强地震主要以走滑和正断层为主,伽师震源区主压应力方向为NNE或近NS向,与相邻的柯坪块体区域构造应力场方向不一致;伽师强震群的破裂面沿NEE方向,属左旋破裂;(2)4~5级中强地震应力场反演得到最大主压应力轴为NNE向,最小主压应力轴为NWW向,中等主应力轴倾角为65°,比较直立;(3)伽师强震群震源区应力场在强震前后经历了一系列变化。最后对所得结果进行了一定的讨论。 相似文献
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对首都圈地区2002年1月～2010年6月619个ML≥2.0地震的震源机制解的基本特征进行了统计分析,并且依据区域构造特征将首都圈划分为3个区域,用聚类统计方法中的最长距离法对各分区的机制解进行了聚类分析,研究了各分区的构造应力张量特征。研究结果表明,首都圈地区震源机制解P轴方位的优势分布为NNE-NEE向,T轴方位的优势分布为NNW-NWW向,绝大多数地震震源处的应力场以水平作用为主,破裂以水平走滑为主。首都圈西部最大主压应力方位为NE75°,中部最大主压应力方位为NE62°,东部最大主压应力方位近EW向,区域构造应力场以水平向挤压为主要特征。 相似文献
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使用近震波形反演方法求解2019年6月17日四川长宁Ms6.0地震序列的震源机制解和震源深度, 共得到30个可靠的M>3.0地震震源机制解和震源深度, 结合该地区已有的震源机制解, 开展震源区构造应力场反演, 小尺度探讨震源区的构造应力环境。 反演结果显示, 震中附近区域主要以逆冲型应力性质为主, 局部地区包括少量走滑分量以及混合类型。 最大主压应力方向主要以NEE向或NE向为主。 在筠连以东地区, 不同于北部的逆冲型, 应力性质以走滑型兼少量混合类型为主, 最大主压应力方向近EW向。 构造应力场方向与形成长宁背斜的构造应力存在一定交角, 2019年长宁6.0级地震可能是由NE或NEE向近水平应力挤压产生的该地区滑脱面之上背斜核部的逆断层活动造成的。 相似文献
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利用CAP方法反演了2012年6月30日新源-和静Ms6.6地震序列震源机制解.反演得到Ms6.6地震节面Ⅰ的参数为:走向299°,倾角68°,滑动角164°;节面Ⅱ的参数为:走向35°,倾角75°,滑动角23°;P轴方位角166°,倾角5°,T轴方位角258°,倾角26°;矩震级Mw为6.3;矩心深度为21km.此次地震序列破裂优势方向为NWW,倾角以60°～90°为主,滑动角以±180°±30°为主;P轴方位的优势取向为近NS向,T轴优势取向为近EW向.初步分析表明,主震节面Ⅰ为发震断层,是走向为NWW、近乎直立的左旋走滑断层.此次6.6级地震震源断错性质和主压应力方向以及序列P轴优势方位与震源区周围构造应力场特征基本一致. 相似文献
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利用地震波资料对澄江5．2级地震序列的震源机制、震源应力场和震源断层作了分析研究。结果表明，整个序列发展中，震源区及附近、构造应力场以南东东方向、水平作用为主的压应力场为主。其次还有南南东向、水平作用为主的压应力场的作用。由序列震源机制解分析，主震发震断层是走向北北东、倾角较陡的断层面，在南南东－南东向，接近水平的压应力场作用下，该断层面具有以左旋走滑为主的错动性质。该断层面是序列的主破裂面。在序列发展过程中，北西西－北西向断层也参与了活动。有的余震，虽然发生在与主破裂面一致或接近的断层面上，但破裂错动的旋性发生了变化，出现了相对主破裂事件的反向错动。极少数余震破裂错动性质呈现以倾向滑动为主的特征。在序列发展过程中，破裂面及其错动性质显地复杂。由于强震的发生，主破裂的错动，使得震源区局部应力场状态错综复杂。 相似文献
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Using the focal mechanism solutions of 24 moderately strong earthquakes in the northern Tianshan area, we carried out system cluster and stress field inversion analysis. The result indicates that, the focal mechanism solutions of moderately strong earthquakes are mainly dipslip reverse faulting in the northern Tianshan area. The principal rupture planes of earthquakes are NW-oriented. It is basically consistent with the strike of earthquake structure in its adjacent area. The direction of the principal compression stress P axis is nearly NS, and its inclination angle is small; while the inclination angle of the principal extensional stress T axis is large. It shows that the regional stress field is mainly controlled by the near-NS horizontal compressive stress. The direction of the maximum principal stress shows a gradation process of NNE-NS-NW from east to west. 相似文献
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新疆伽师及周围构造应力场区域特征探讨 总被引：1，自引：0，他引：1
在利用伽师及周围58次中强地震震源机制解对这一地区的构造应力场进行分析的基础上,结合系统聚类和应力场反演计算结果,对不同时期、不同区域应力场的变化特征进行了分析。该区域地震以走滑错动为主,柯坪块体逆冲作用更为明显。区域最大主压应力方向近SN,但不同构造背景下的主压应力方向存在着较明显的差异。乌恰-喀什地区P轴基本近SN向,但存在着由NW—SN—NE的随时间变化的过程;柯坪块体内部长期以来受较为一致的NW-SE向压应力作用;伽师震区P轴方向为NE-SW。1996年区域应力场方向开始发生明显的变化,P轴方位向NE偏转,倾角增大。结果表现出不同构造环境下应力场分布格局的特征或变化 相似文献
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Gao Guoying 《中国地震研究》2007,21(4):397-408
Jiashi and its surrounding areas are composed of many structural zones. Using the focal mechanism solutions of 59 moderately strong earthquakes in Jiashi and its surrounding areas, and combining these with the calculation results of system cluster and stress field inversion, we analyzed the evolvement characteristics of the stress field for different times and different regions. The results were as follows: The earthquakes in Jiashi are mainly strike-slip. However, those of the Kalpin block are mainly reverse events, showing an obvious thrusting. The regional characteristics are different from other areas. The direction of the regional principal stress field is near NS. However, under different tectonic backgrounds, the directions of the stress fields are different. The direction of the principal compress stress is near NS in the Kashi-Wuqia area. But before and after the 3 earthquakes with M7.0, dynamic evolution from NW to NS and then to NE with time process was observed. The Kalpin block has been dominated by a consistent stress field in the NW direction for a long time. However, the direction of the stress field of the Jiashi region is NE. Since 1996, the direction of the regional stress field has changed obviously. The direction of the P axis was deflected towards the NE, and the plunge angle increased. The result shows clearly the regional characteristics and variation of the distribution pattern of the stress field in different tectonic environments. 相似文献
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乌鲁木齐地区构造应力场与中强震活动特征研究 总被引：14，自引：4，他引：10
为了做好中强地震的震预报和震后趋快速判定工作,利用乌鲁木齐地区中强震震源机制解,小震平均震源机制解以及Ｓ波偏振方向综合研究了该区域应力场的分布和中强地震的活动特征。 相似文献
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PRELIMINARY APPLICATION OF FOCAL MECHANISM SOLUTIONS OF SMALL AND MEDIUM-SIZE EARTHQUAKES TO FAULT STABILITY ANALYSIS IN THE SOUTHEASTERN TIBETAN PLATEAU 
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下载免费PDF全文 Analysis of stress state of faults is helpful to understand crustal mechanical properties and seismicity. In the paper, we invert the horizontal crustal stress field in the southeastern Tibetan plateau using focal mechanism solutions of small and medium-size earthquakes, and apply them to estimate the stability of regional major faults.
Firstly, we collect focal mechanism solutions of small and medium-sized earthquakes in the southeastern Tibetan plateau. The dataset includes more than 1 000 focal mechanism solutions in the past twenty years. Magnitudes of these earthquakes vary from M3.0 to M6.0. Most of the focal mechanism solutions were determined using waveform inversion technique. Although most of focal mechanism solutions in the southeastern Tibetan plateau are strike-slip faulting, their spatial pattern is different in sub-regions. Normal faulting earthquakes mainly occurred in the western Sichuan region, reverse faulting earthquakes mainly occurred in the boundary zone between the Tibetan plateau and the South China craton, and strike-slip faulting earthquakes mainly occurred in the central and southern Yunnan region.
Next, we settle on a mesh with grid spacing of 0.5° in longitude and latitude in the region and invert the horizontal crustal stress field at each grid point. Spatial variation of the maximum principal stress axis in the southeastern Tibetan plateau shows a clockwise rotation around the eastern Himalaya syntax. The azimuth of maximum compressional stress axis is about 88.1° in the western Sichuan region, about 124.6° in the South China craton, and about 21.6° in the western and southern Yunnan region. The azimuth of regional maximum compressional stress is nearly parallel to the direction of terrain elevation gradient, and that of the minimum compressional stress is nearly parallel to the tangential direction of the topographic elevation contours. The spatial pattern reflects the control role of gravity spreading of the Tibetan plateau on the regional horizontal stress field.
Finally, we analyzed regional fault stability based on these collected focal mechanism solutions. The fault instability parameter (I) is defined based on the Mohr-Coulomb criterion and indicates the degree of fault approximating to rupture. The instability parameters on fourteen major faults in the southeastern Tibetan plateau were calculated. Our results show that the stability of the Lianfeng-Zhaotong Fault is the lowest before 2014 in the region, which indicates the fault zone is close to rupture at that time. Our results provide a new useful tool to assess regional seismic potential using dense focal mechanism solutions. 相似文献
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利用垂直向和波振幅比方法计算了2003年1月至2009年10月间宁夏北部及邻区的31个中小地震震源机制解,然后对计算所得的31个地震震源机制解进行系统聚类及应力场分析,并利用格点尝试法研究阿拉善区域（I区）和银川盆地及以北地区（II区）的平均震源机制解。结果表明：31个中小地震中走滑型地震占了近77％,显示出宁夏北部及邻近地区地震错动方式以近走滑为主;I区域地震产生的震源区构造变形是近南北向发生压缩,近东西向发生相对扩张;II区域构造应力场主压应力方向以水平作用为主,地震产生的震源区构造变形是北东向发生压缩,北西向发生相对扩张。 相似文献
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1996年3月19日新疆阿图什6.9级地震震源破裂特征的研究 总被引：4，自引：0，他引：4
通过对1996年3月19日新疆阿图什6．9级地震余震分布特征的研究，分析了这次地震震源破裂过程．并结合柯坪断裂带的构造运动、区域应力场的分布特征以及1972年以来该带的另外3次6级地震的余震分布方向，探讨了柯坪断裂带附近地区不同构造部位震源破裂扩展方向与强震活动的迁移方向．结果表明，本次地震震源破裂为明显的单侧破裂．柯坪断裂带的阿图什震区和柯坪震区，余震分布具有一定规律性，震源破裂基本都为单侧破裂；震源断错以逆断层为主．区内主要受NW向压应力。不同地段强震震源破裂扩展具有明显的区域特征，强余震分布方向是应力集中的体现，它标志着同一构造断裂带附近近期强震活动的迁移方向．在柯坪断裂带上这种规律更为明显。 相似文献