THREE-DIMENSIONAL DEFORMATION CHARACTERISTICS OF THE XIANSHUIHE FAULT ZONE     

ZHAO Jing  REN Jin-wei  JIANG Zai-sen  Yue Chong 《地震地质》2018,40(4):818-831

In order to analyze 3-dimensional movement and deformation characteristics and seismic risk of the Xianshuihe fault zone, we inverted for dynamic fault locking and slip deficit rate of the fault using the GPS horizontal velocity field of 1999-2007 and 2013-2017 in Sichuan-Yunnan region, and calculated annual vertical change rate to analyze the vertical deformation characteristics of the fault using the cross-fault leveling data during 1980-2017 locating on the Xianshuihe fault. The GPS inversion results indicate that in 1999-2007, the southeastern segment of the fault is tightly locked, the middle segment is less locked, and the northwestern segment is basically in creeping state. In 2013-2017, the southeastern segment of the fault is obviously weekly locked, in which only a patch between Daofu-Bamei is locked, and the northwestern segment is still mostly in creeping state, in which only a patch at southeastern Luhuo is slightly locked from surface to 10km depth. The cross-fault leveling data show that annual vertical change rate of the Zhuwo, Gelou, Xuxu and Goupu sites on the northwestern segment is larger, which means vertical movement is relatively active, and annual vertical change rate of the Longdengba, Laoqianning, and Zheduotang sites on the southeastern segment is small, which means the fault is locked, and the vertical movement changes little before and after the Wenchuan earthquake. Combining with the 3-dimensional movement and deformation, seismic activity and Coulomb stress on the Xianshuihe Fault, we consider the seismic risk of the southeastern segment is larger, and the Wenchuan earthquake reduced the far-field sinistral movement and the fault slip deficit rate, which may reduce the stress and strain accumulation rate and relieve the seismic risk of the southeastern segment.  相似文献   

鲜水河断裂带乾宁段岩石特征与内部结构及其物理-化学性质     

吴琼  李海兵  CHEVALIER Marie-Luce  米桂龙  李超  何祥丽  李亚林 《岩石学报》2021,37(10):3204-3224

断裂带的变形行为和断层滑移机制是目前地震研究关注的热点,断裂带岩石特征、内部结构与物理化学性质是确定断层蠕滑或粘滑行为以及断层滑移机制的基础和关键。本文以鲜水河断裂带乾宁段地表出露的断裂岩为研究对象,通过野外地质调查、室内光学显微镜、扫描电镜、粒度统计、粉末X射线衍射分析（XRD）和薄片X射线荧光光谱分析（XRF）等多种研究方法,对鲜水河断裂带岩石特征、结构构造、物性、矿物成分及化学元素分布开展了详细的分析,并探讨了相关变形行为和滑移机制。分析表明：（1）断裂带核部主要由黑色断层泥、浅黄色及黄色断层角砾岩和灰色碎裂岩、灰色断层角砾岩组成,呈单核对称结构;（2）黑色断层泥厚3~5cm,具有快速滑动结构特征,表现为断层粘滑行为。断层泥可划分出13个滑移带,最窄滑移带厚约40μm,至少代表13期古地震事件;（3）断层泥主要由伊利石、高岭石和石英等矿物组成,其中边部伊蒙混层含量异常高,为最新一次古地震的主滑移带。由于伊利石和伊蒙混层（或蒙脱石）为主要黏土矿物的断层泥渗透率低、孔隙流体压力大,以及发现断层泥楔入脉,表明地震过程中断层滑动存在热增压弱化机制;（4）从断层泥不同滑动带中碎块蚀变程度和矿物分布特征来看,地震主滑动带有向碎裂岩方向迁移的趋势。推测断层在滑动过程中,更趋向于向弱矿物含量高（如伊利石、伊蒙混层）、强矿物含量低（如方解石、高岭石）的围岩一侧迁移。  相似文献   

甘孜-玉树断裂带晚第四纪走滑速率与滑动分解作用     

吕丽星  李传友  魏占玉  董金元  谭锡斌  石峰  苏鹏 《震灾防御技术》2017,12(3):456-468

滑动速率是研究断裂运动学特征、地震活动性和区域应变分配的重要参数和依据。前人关于甘孜-玉树断裂带滑动速率的研究结果存在较大差异，因此，其晚第四纪滑动速率有待进一步调查研究。本文基于卫星影像解译和野外实地考察，对甘孜-玉树断裂带西段（玉树断裂）上典型断错地貌点进行测量分析，得到玉树断裂晚第四纪走滑速率为6.6±0.1-7.4±1.2mm/a。通过与前人对甘孜-玉树断裂带东段（甘孜断裂）滑动速率的研究结果进行对比，发现甘孜-玉树断裂带东、西段滑动速率不一致，其原因是甘孜断裂的左旋滑移在向西传递的过程中，一部分应变被分配到了巴塘盆地南缘断裂上。巴塘盆地南缘断裂的存在很好地解释了玉树断裂的走滑速率比甘孜断裂偏低的原因。但是，从区域变形来看，巴塘盆地南缘断裂分配的滑动速率恰好说明了甘孜-玉树断裂带东、西段及鲜水河断裂带的水平构造变形是协调一致的。  相似文献   

鲜水河断裂带北西段跨断层基线变化机理探讨   总被引：1，自引：1，他引：0       下载免费PDF全文

李玉江  陈连旺  刘少峰  季灵运  占伟 《地球物理学报》2017,60(2):554-563

2013年芦山M_s7.0地震发生后,鲜水河断裂北西段的侏倭、虚墟等跨断层测点基线测项均出现不同程度的异常变化,异常核实结果认为基线异常属实.该异常变化是否与芦山地震的发生存在一定关联性,值得深入研究.本文首先分析芦山地震发生前后鲜水河断裂北西段不同基线长度的变化特征.基于鲜水河断裂带及邻区三维非线性黏弹性有限元模型,以GPS观测资料、同震静态滑移量作为约束,通过开展多组数值模拟实验,探讨下地壳不同流变特征下,芦山地震发生前后不同阶段,不同跨断层基线长度的时序动态变化特征.初步研究结果表明,1)侏倭、虚墟基线测点原始观测资料均表现出地震发生时基线长度减小,发生后短时间内反向快速恢复及增加的协同变化;2)在以GPS观测数据为约束的块体间差异性运动的动力学边界条件下,鲜水河断裂表现为左旋走滑运动;3)模拟结果显示,地震发生时测点间距离迅速减小,表现为断层右旋的特征,这与实际观测资料反映的结果一致;4)鲜水河断裂带两侧地块的下地壳黏滞系数分别取10~(18)Pa·s、10~(19)Pa·s时,由于黏弹性松弛效应的影响,造成基线长度在地震发生后短时间尺度内快速增加.对比分析认为,地震后短时间内实测资料反映的基线长度快速增加的特征可能是黏弹性松弛效应与构造作用共同作用的结果.  相似文献   

Dynamic simulation of interactions between major earthquakes on the Xianshuihe fault zone   总被引：3，自引：0，他引：3  

Hui Wang  Jie Liu  YaoLin Shi  Huai Zhang  GuoMin Zhang 《中国科学D辑(英文版)》2008,51(10):1388-1400

The authors firstly evaluate the strain accumulation rate of the Xianshuihe fault zone based on earth- quake activity. We calculated the stress and seismic moment accumulation rate for each subsection of the Xianshuihe fault zone based on the distribution of geological slip rate and GPS survey results. According to the results, we get the recurrence intervals of characterized earthquakes on each sub- section respectively. A three-dimensional finite element model for western Sichuan is constructed to discuss the earthquakes triggering among major earthquakes (M>6.7) that occurred along the Xianshuihe fault zone since 1893. The calculated Coulomb failure stress changes (ΔCFS) show that 5 of the 6 earthquakes with Ms>6.7 were triggered by positive ΔCFS. The interactions between major earthquakes not only influence recurrence intervals of characterized earthquakes on each subsection, but also change recurrence behavior of major earthquakes along the whole fault zone.  相似文献   

3D modeling of earthquake cycles of the Xianshuihe fault,southwestern China     

《Journal of Asian Earth Sciences》2014

We perform 3D modeling of earthquake generation of the Xianshuihe fault, southwestern China, which is a highly active strike-slip fault with a length of about 350 km, in order to understand earthquake cycles and segmentations for a long-term forecasting and earthquake nucleation process for a short-term forecasting. Historical earthquake data over the last 300 years indicates repeated periods of seismic activity, and migration of large earthquake along the fault during active seismic periods. To develop the 3D model of earthquake cycles along the Xianshuihe fault, we use a rate- and state-dependent friction law. After analyzing the result, we find that the earthquakes occur in the reoccurrence intervals of 400–500 years. Simulation result of slip velocity distribution along the fault at the depth of 10 km during 2694 years along the Xianshuihe fault indicates that since the third earthquake cycle, the fault has been divided into 3 parts. Some earthquake ruptures terminate at the bending part of the fault line, which may means the shape of the fault line controls how earthquake ruptures. The change of slip velocity and displacement at 10 km depth is more tremendous than the change of the shallow and deep part of the fault and the largest slip velocity occurs at the depth of 10 km which is the exact depth of the seismic zone where fast rupture occurs.  相似文献   

鲜水河断裂带现今断层运动短周期事件的发现与初步研究     

周硕愚  施顺英  宋永厚  张鸿旭  刘本培  吴云 《大地测量与地球动力学》1996,(4)

根据鲜水河断裂带上连续动态地壳形变台阵数据，首次揭示了中国大陆板内断层现今运动的短周期现象，包括蠕变阶、蠕变坡和脉动等，其持续时间为数分钟至数十小时。发现其空间分布与断层分段（闭锁或活动段）有关；其时间分布与强地震孕育过程有关。蠕变过程符合Ｌｏｍｎｉｚ提出的对数蠕变函数，可能是断层面不均匀结构中的局部流变行为。断层短周期事件对揭示断层不均匀结构和微破裂过程动力学有重要意义，并可能发展为一种新的地震前兆  相似文献   

利用地震矩张量反演鲜水河断裂带现今运动学特征     

孙建中  施顺英  周硕愚  张爱华 《大地测量与地球动力学》1994,(4)

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形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）和现今地壳形变测量（８ｍｍ／ａ）的结果相当。同时，反演出的应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，从而证明该方法是目前研究区域运动学问题切实有效的手段之一。  相似文献   

Late-Quaternary Slip Rate and Seismic Activity of the Xianshuihe Fault Zone in Southwest China   总被引：1，自引：1，他引：0  

ZHANG Yongshuang  YAO Xin  YU Kai  DU Guoliang  and GUO Changbao 《《地质学报》英文版》2016,90(2):525-536

The Xianshuihe fault zone is a seismo-genetic fault zone of left-lateral slip in Southwest China. Since 1725, a total of 59 Ms ≥ 5.0 earthquakes have occurred along this fault zone, including 18 Ms 6.0–6.9 and eight Ms ≥ 7.0 earthquakes. The seismic risk of the Xianshuihe fault zone is a large and realistic threat to the western Sichuan economic corridor. Based on previous studies, we carried out field geological survey and remote sensing interpretation in the fault zone. In addition, geophysical surveys, trenching and age-dating were conducted in the key parts to better understand the geometry, spatial distribution and activity of the fault zone. We infer to divide the fault zone into two parts: the northwest part and the southeast part, with total eight segments. Their Late Quaternary slip rates vary in a range of 11.5 mm/a –(3±1) mm/a. The seismic activities of the Xianshuihe fault zone are frequent and strong, periodical, and reoccurred. Combining the spatial and temporal distribution of the historical earthquakes, the seismic hazard of the Xianshuihe fault zone has been predicted by using the relationship between magnitude and frequency of earthquakes caused by different fault segments. The prediction results show that the segment between Daofu and Qianning has a possibility of Ms ≥ 7.0 earthquakes, while the segment between Shimian and Luding is likely to have earthquakes of about Ms 7.0. It is suggested to establish a GPS or In SAR-based real-time monitoring network of surface displacement to cover the Xianshuihe fault zone, and an early warning system of earthquakes and post seismic geohazards to cover the major residential areas.  相似文献   

鲜水河断裂带炉霍段的震后滑动与形变   总被引：5，自引：0，他引：5       下载免费PDF全文

杜方  闻学泽  张培震 《地球物理学报》2010,53(10):2355-2366

1973年2月在鲜水河断裂带炉霍段发生了M7.6地震破裂.自那以来,先后在炉霍县虾拉沱布设了若干横跨该地震断层(1973年破裂带)的地壳形变观测系统,包括断层近场的短基线、短水准、蠕变仪、人工构筑物等,以及断层近-远场的GPS观测站.利用这些观测系统的长期观测资料,本文分析了鲜水河断裂带炉霍段的震后滑动/变形及其时、空变化特征,并建立起解释这些特征的动力学模式.研究表明:(1)1973年地震后的头5年,地震断层在虾拉沱场地表现为开放性质,近场的断层震后滑动以无震左旋蠕滑为主,速率达到10.27 mm/a,且伴有微量的拉张性蠕动作用;1979年以来,左旋蠕滑速率由5.3 mm/a逐渐减小到2.27 mm/a,减小的过程呈对数函数型,反映此阶段断层面已逐渐重新耦合、正朝闭锁的方向发展,并伴有部分应变积累.(2)1999年以来,地震断层两侧远场的相对左旋位移/变形速率为10 mm/a,远大于同时期断层近场(跨距40~144 m)的左旋蠕滑速率0.66~2.52 mm/a;远-近场位移/形变速率的显著变化发生在地震断层两侧各宽约30 km的范围,显示出这是与大地震应力应变积累-释放相关的断裂带宽度.(3)结合动力学背景与深部构造信息,本文对这里断层的震后位移/变形及其时、空变化的机理进行初步解释,要点是:震后约5年之后,由于逐渐增大的断层滑动/摩擦阻抗,上地壳脆性层中的断层面由震后初期的开放性质逐渐转向重新耦合、并朝闭锁的方向发展,但其两侧地块深部持续的延性相对运动拖拽着浅部脆性层发生相应的弹性位移/变形.(4)可估计再经历15~25年,研究断裂段将完全"闭锁",即进入积累下一次大地震应力应变的震间闭锁阶段.  相似文献