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为了综合分析讨论鲜水河断裂带的三维运动与变形动态特征和地震危险性,利用川滇地区1999—2007和2013—2017 2期GPS速度场资料,反演计算了鲜水河断裂带的闭锁程度和平行与垂直断层的滑动亏损速率动态分布;利用布设在鲜水河断裂带附近的1980—2017年跨断层短水准资料,通过计算断层年均变化速率分析了断裂带垂直运动特征。GPS反演结果显示:1999—2007期鲜水河断裂SE段处于强闭锁状态,中段闭锁程度逐渐减弱,到NW段基本为蠕滑状态;2013—2017期鲜水河断裂SE段滑动亏损积累速率明显减弱,只有道孚—八美段之间有一小段闭锁较强,NW段依然大部分为蠕滑状态,只有炉霍SE部一段断层地表至10km深度闭锁稍有增强。水准结果显示:鲜水河断裂NW段侏倭、格篓、虚墟和沟普场地年均垂直变化速率较大,断层垂向活动较为活跃;SE段龙灯坝、老乾宁和折多塘场地年均垂直变化速率很小,断层垂向活动处于闭锁状态;汶川地震后断层垂向活动变化并不明显。综合分析认为鲜水河断裂SE段的地震危险性较高,而汶川地震降低了断层滑动亏损和应力应变能积累速率,可能在一定程度上缓解了鲜水河断裂尤其SE段的地震紧迫性。 相似文献
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本研究以鲜水河断裂带为例,通过断层三维活动参数、断层活动信息合成和主成分分析等方法,对汶川8.0、芦山7.0和康定6.3级地震前后鲜水河断裂带地区的跨断层形变资料进行了综合分析;计算断层水平扭错速率、水平张压活动速率的各个主成分和能够反映断层总体活动水平的综合指标W.结果表明:主成分分析方法能够最大限度地保留原始信息,... 相似文献
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鲜水河断裂带在印度板块与欧亚板块顶撞作用的驱使下,表现了强烈的左旋走滑运动及频繁的强震活动,是我国西南地区重要的强震发动带。本文根据断层长期平均位错速率与地震滑动速率的对比,认为鲜水河断裂带第四纪以来的阶层错开是地震位错重复迭加的结果。在地震时断层水平位错分布研究的基础上,结合地震破裂在断裂带内的分布认为沿鲜水河断裂在乾宁南北两侧存在两个长度不大的地震破裂空区。它们可能以断层蠕动为特征,其存在对乾宁附近应变积累与释放起着不可忽视的制约与调节作用。最后,按Chinncry走滑断层地震水平位错分布的理论模型计算了鲜水河断裂带近250年的地震位错分布,结合弹性回跳理论的基本原理估计了鲜水河断裂带的强震趋势。认为未来强震将迁往乾宁,康定一带。 相似文献
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川西及邻区分布着中国大陆数条重要的活动断裂带,这些断裂带上的滑动速率与地震活动有很大差异,如鲜水河断裂带的滑动速率在10mm/a以上,该断裂带上大地震频繁发生;而龙门山断裂带的滑动速率很小,虽然该断裂带上地震活动不频繁,但也发生了2008年5月12日汶川Ms8.0级大地震.利用弹黏塑性三维有限元模型,研究川西地区断裂带的几何形态及走向变化对断层滑动速率及区域应变分配影响.结果表明:鲜水河-小江断裂带的滑动速率随着断裂带几何分布及其走向呈现分段特征.结构简单,走向平直的分段滑动速率大;结构复杂,走向变化大的分段滑动速率低,区域应变主要集中在断裂带走向发生急剧变化的分段附近.鲜水河-小江断裂带中段的应变分配受到安宁河-则木河断裂带与大凉山断裂带相互作用的影响.龙门山断裂带的走向与青藏高原的挤出方向近乎垂直,断层活动以逆冲为主,滑动速率较低. 相似文献
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鲜水河GPS监测网由18个沿鲜水河断裂带分布的点组成.1991年对该网进行了首次观测,1996和2000年进行了两期整网复测.本利用该网199l和2000年的二期GPS观测资料结合川西地区20世纪70年代以来的常规大地测量资料,计算给出了这一强震活动带现今运动图像:由测区的北西虾拉沱测点到南东的乾宁测点水平位移速率逐渐增大,而断层两盘的相对运动不明显.表明利用短边GPS测量可有效监视活动断裂带两侧一定区域的地壳运动.对比有形变测量资料以来川西地区6级以上地震分布的特点,认为可根据鲜水河断裂带断层两盘的相对运动和跨越断层的地壳整体运动的强弱这两种运动图像来研究区域强震的活动特征. 相似文献
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利用鲜水河断裂带1990年1月-2009年12月的蠕变与短基线数据,采用小波变换与断层运动学分析方法,获取构造活动产生的断层形变速率.结合近场断层形变测量与GPS资料,分析了该断裂带的分段活动特征及时空演化.结果显示:(1)不同段落断层活动方式存在差异性.鲜水河断裂带分段活动现象显著,以道孚县为界,以北的炉霍、道孚断层走滑量相对较大且活动方式稳定,显示张性和左行走滑;以南的乾宁、折多塘断层活动微弱,走滑量小,且滑动状态复杂,其中,乾宁断层为压性和左行走滑,折多塘断层为微弱的右行走滑.这种分段活动特征可能与断层几何及巴颜喀拉块体内部次级块体的差异运动有关.(2)不同时期断层走滑方式存在交替性.鲜水河断裂带虽以左行走滑为主,但在汶川地震前一些断层段出现过逆向走滑现象.汶川地震前2年,炉霍、道孚断层左行走滑减弱,乾宁、折多塘断层在2007年出现过逆向走滑,至2009年底,逆向走滑区域保持扩展态势.(3)不同测点间距得到的断层错动速率和变形带空间分布特征不同.不同测量方法的分析结果表明,鲜水河断裂带不同段落和跨距宽度的走滑速率有所不同:测点间距18.7~65.1 m的蠕滑速率为0.01~0.78 mm/a;测点间距72~288 m的短基线测量为0.02~2.46 mm/a,点距十几至几十公里的GPS观测为6~11 mm/a;地质滑动速率5~15 mm/a.随测点间距的增加,平行断层的位移速率按对数函数增长,视剪应变率按幂函数衰减.我们推测,大间距测点的数据中既包含了跨断层的错动,也包含了断层两侧块体的分布变形;现今的断层形变测量与地质调查之间的差异,说明断层错动速率在时间上不是常数. 相似文献
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利用地震矩张量演鲜水河断裂带现今运动学特征 总被引:1,自引:0,他引:1
本文探讨了利用地震矩反演断裂形变带运动学参数的基本理论和方法,将其初步应用于鲜水河断裂形变带变带分析和运动机制的研究。结果表明,鲜水河断裂带呈现出走向拉伸,倾向压缩的形变格局。由地震矩反演的断裂带剪切形变速率(10.9mm/a)与用地质学估算方法(17mm/a)和现今地过壳形变测量(8mm/a)的结果相当。同时,反演出的变主方向能解释鲜水河断裂现今活动分段性特征以及多种滑动方式共存的现状,从而证明 相似文献
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初步研究了2000年6月6日甘肃景泰5.9级地震蕴育过程中近源区及外围地区断层形变异常的时空分布特征:震前断层形变异常分布范围广、异常形态复杂,断层形变(应变)类信息指标图象异常区明显.不同地域断层形变异常形态及幅度存在显著差异,与异常所处的构造部位密切相关:海原断裂带西段出现的,,相断层形变异常,显示了近源区断层运动由准线性走向非线性的过程,与断层形变(应变)类信息指标高值异常区相配合,反映蕴震区应变积累程度高;而构造汇聚部位的六盘山断裂带等远场区较大幅度的突跳尖点异常,并不反映所在地的应变积累,而可能是蕴震过程区域构造应力场增强的一个标志.在此基础上,结合对景泰5.9级地震中短期预报经验教训的初步总结,研究和探讨了断层形变异常在震情判定中的应用. 相似文献
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THE CRUSTAL SHALLOW STRUCTURES AND FAULT ACTIVITY DETECTION IN XINYI SECTION OF TAN-LU FAULT ZONE
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GU Qin-ping XU Han-gang YAN Yun-xiang ZHAO Qi-guang LI Li-mei MENG Ke YANG Hao WANG Jin-yan JIANG Xin MA Dong-wei 《地震地质》1979,42(4):825-843
The Tan-Lu fault zone is the largest active tectonic zone in eastern China, with a complex history of formation and evolution, and it has a very important control effect on the regional structure, magmatic activity, the formation and distribution of mineral resources and modern seismic activity in eastern China. Xinyi City has a very important position as a segmental node in the Shandong and Suwan sections of the Tan-Lu fault zone. Predecessors have conducted research on the spatial distribution, occurrence and activity characteristics of the shallow crustal faults in the Suqian section of the Tan-Lu belt, and have obtained some new scientific understandings and results. However, due to different research objectives or limitations of research methods, previous researches have either focused on the deep crustal structure, or targeted on the Suqian section or other regions. However, the structural style and deep-shallow structural association characteristics of Xinyi section of Tan-Lu belt have not been well illustrated, nor its activity and spatial distribution have been systematically studied. In order to investigate the shallow crustal structure features, the fault activities, the spatial distribution and the relationship between deep and shallow structures of the Xinyi section of the Tan-Lu Fault, we used a method combining mid-deep/shallow seismic reflection exploration and first-break wave imaging. Firstly, a mid-deep seismic reflection profile with a length of 33km and a coverage number greater than 30 was completed in the south of Xinyi City. At the same time, using the first arrival wave on the common shot record, the tomographic study of the shallow crust structure was carried out. Secondly, three shallow seismic reflection profiles and one refraction tomography profile with high resolution across faults were presented. The results show that the Xinyi section of Tan-Lu fault zone is a fault zone composed of five concealed main faults, with a structural pattern of “two grabens sandwiched by a barrier”. The five main faults reveal more clearly the structural style of “one base between two cuts” of the Tan-Lu fault zone. From west to east, the distribution is as follows: on the west side, there are two high-angle faults, F4 and F3, with a slot-shaped fault block falling in the middle, forming the western graben. In the middle, F3 and F2, two normal faults with opposite dip directions, are bounded and the middle discontinuity disk rises relatively to form a barrier. On the east side, F2 and F1, two conjugate high-angle faults, constitute the eastern graben. The mid-deep and shallow seismic reflection profiles indicate that the main faults of the Xinyi section of Tan-Lu fault zone have a consistent upper-lower relationship and obvious Quaternary activities, which play a significant role in controlling the characteristics of graben-barrier structure and thickness of Cenozoic strata. The shape of the reflective interface of the stratum and the characteristics of the shallow part of the fault revealed by shallow seismic reflection profiles are clear. The Mohe-Lingcheng Fault, Xinyi-Xindian Fault, Malingshan-Chonggangshan Fault and Shanzuokou-Sihong Fault not only broke the top surface of the bedrock, but also are hidden active faults since Quaternary, especially the Malingshan-Chonggangshan Fault which shows strong activity characteristics of Holocene. The results of this paper provide a seismological basis for an in-depth understanding of the deep dynamics process of Xinyi City and its surrounding areas, and for studying the deep-shallow tectonic association and its activity in the the Xinyi section of the Tan-Lu Fault. 相似文献
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通过对北京密云北石城断裂带的野外和室内工作,该断裂带的断层岩可分为四种类型:碎裂岩类、糜棱岩类、假熔岩和断层泥。它们具有不同的矿物学、形变和组构特征,分别代表不同的成因机制。假熔岩和碎裂岩类断层岩的存在,可作为古地震事件的可能证据。前者是地震断层运动在断层面上摩擦增温,引起围岩中矿物的选择性熔化形成的。在该断裂带中可能发生不止一次的古地震事件。断层岩特征和产状表明,该断裂带经历了两种不同力学性质的运动,早期为韧性剪切;晚期为脆性破裂,并伴有地震发生 相似文献
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The Ximalin fault is the northwest section of the Ximalin-Shuiquan fault, which is part of the north-edge fault zone of the Yanghe Basin, located in the conjunction of the Zhangjiakou-Bohai fault zone and Shanxi fault-depression basin, and its structural geometry and deformation characteristics can facilitate the research on the interaction of the two tectonic belts. In this paper, data of geological surveys and geophysical exploration are used to study this fault exhaustively, concerning its geometry, structural features and activity as well as its relationship with adjacent faults and rule in the deformation transform of the north-edge fault zone of the Yanghe Basin. The results show that the Ximalin Fault is a strike-slip feature with thrust component. Its vertical slip rates are 0.17mm/a and 0.25~0.38mm/a, and the horizontal slip rate is 0.58~0.67mm/a and 0.50mm/a during the late Middle Pleistocene and Holocene, respectively. It is formed alternately by the NW-trending main faults and secondary NE-trending faults, of which the former is characterized by high-angle reverse with sinistral strike-slip, and the latter shows normal faulting. The two sets of structures have specific structural geometry relations, and the motion manners and deformation characteristics match each other. During the active process of the north-edge fault of the Yanghe Basin, the NW trending Ximalin fault played a role similar to a transform fault in deformation change and stress transfer, and its sinistral strike slip activity accommodated the NE trending normal faulting at the both ends. 相似文献
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CHANGES IN FAULT MOVEMENT PROPERTY AND GENETIC MECHANISM ON THE WESTERN SEGMENT OF THE XIANGSHAN-TIANJINGSHAN FAULT ZONE
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The Xiangshan-Tianjingshan fault zone is an important part of the arc tectonic zone in northeastern Tibet, whose eastern segment is characterized by primarily left-lateral slip along with thrust component. In contrast, the fault movement property on the western segment of the Xiangshan-Tianjingshan fault zone is more complicated. According to the offset geomorphic features and cross sections revealed by the trenches and outcrops, the western segment is mainly a left-lateral strike-slip fault with normal component, and only accompanied with reverse component at specific positions. To determine the genetic mechanism of fault movement property on the western segment, we obtained three main factors based on the integrated analysis of fault geometry:(1)Step-overs:the left-stepping parallel faults in a sinistral shear zone create extensional step-overs and control the nearby and internal fault movement property; (2)terminal structures:they are conductive to stop rupture propagation and produce compressive deformation at the end of the fault trace; and(3)double bends:strike-slip faults have trace that bends such that slip between two adjacent blocks creates a compressive stress and thrust fault. Additionally, the Tianjingshan sub-block moves to SEE and creates an extensional stress at the end of the sub-block associated with normal faults. It shows that the Xiangshan-Tianjingshan fault zone has a complex evolution history, which is divided into two distinctive periods and characterized by laterally westward propagating. 相似文献
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怒江断裂带从走向上可以分为南北走向段和北东走向段,其喜马拉雅期的构造变形以右行剪切为主导。右行剪切的变形历史可以分为早期压剪变形和晚期张剪变形两个大的阶段。这两期变形各自在南北走向段和北东走向段表现出不同的特点。总之,怒江断裂带喜马拉雅期构造变形具有时空不均一性的特点 相似文献
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WANG Lei SHEN Jun YU Xiao-hui WAN Yong-kui YU Yang SHAO Bo YANG Chuan-cheng 《地震地质》2016,38(2):447-457
The Gudian Fault in the southwest of Songyuan is an important fault in the central depression of the Songliao Basin. It was recognized from the petroleum exploration data. Based on the data, we conducted shallow seismic exploration, drilling exploration, age determination(OSL) and topography measurement. The fault features and its motion characteristics are analyzed with the results of shallow seismic exploration. With stratigraphic correlation and optical stimulated luminescence dating, the latest active age of the fault is determined. The surface relief of the region to the southeast of the drilling site is relatively larger than surrounding places. An 800m long section across the fault was measured by GPSRTK, and the deformation amount across the zone was calculated. Four conclusions are drawn in this paper:(1) The Gudian Fault is arcuate in shape and shows a property of inverse fault with a length of about 66km in the reflection interface T1(bottom of the upper Cretaceous Nenjiang Group). (2) The middle part of the fault rupture is wider than the ends, narrowing or dying out outwards. According to this feature and the rupture of the bottom of the fourth segment of the upper Cretaceous Nenjiang Group, the fault can be divided into three segments, e.g. Daliba Village-Gaizijing-Guyang segment, Guyang-Shenjingzi-Julongshan Village segment and Julongshan Village-Caiyuanzi segment. (3) The yellow silt layer at the base of the upper Pleistocene series ((33.66±3.27) ka BP~50ka BP) is offset by the Gudian Fault, while the upper tawny silt layer is not influenced by the fault. Thus, the fault belongs to late Pleistocene active fault. (4) The amount of geomorphic deformation around Shenjingzi is 9m. The depth of the bottom of the upper Pleistocene series is 11m and the Huangshan Group of the mid Pleistocene series exposes to the southeast of the deformation zone. Therefore, the throw of the bottom of the upper Pleistocene series is about 20m at the sides of the deformation zone. In addition, the Qianguo M6(3/4) earthquake occurred in Songyuan area in 1119 AD. Though some studies have been done, arguments still exist on the seismogenic structure of the Qianguo M6(3/4) earthquake. Combined with others studies, Gudian Fault is considered as the seismogenic structure of the Qianguo M6(3/4) earthquake. 相似文献