历史大地震断层滑动模型的建立及其对同震数值计算的影响——以1920年宁夏海原M_S8.5大地震为例          下载免费PDF全文

邓园浩  程惠红  张贝  张怀  石耀霖 《地球物理学报》2018,61(3):975-987

大地震的发生会引起区域位移场和应力场发生变化，进而改变区域内及临近断层的应力状态和地震活动性.目前，研究学者可据已有的断层滑动模型来计算分析大地震同震应力变化，同时采用库仑应力触发理论来进一步分析震后余震分布和断层危险性.然而，历史上曾经发生过不少大地震，例如，1920年的海原M_S8.5大地震，是全球范围内少见的特大地震之一.局限于无确切的地震台站地震波等资料，前人在研究历史地震的影响时往往给出一些简单的断层滑动模型，将断层面上错动量视为均匀分布.为更准确地了解历史地震对后续地震的影响，基于前人研究和一般地震滑动形态分布规律及地震反射剖面等资料，以海原M_S8.5大地震为例，探讨了如何建立海原大地震断层滑动模型，并分别搭建了简单断层滑动模型和复杂断层滑动模型的全球同震横向不均匀并行椭球型地球模型.通过对海原M_S8.5地震的同震位移场和应力场的计算，发现采用复杂断层滑动模型比简单断层滑动模型地表位错分布更切合实际.同时，进一步计算和分析了此次大地震对青藏高原东北缘近100年历史地震和周围断层的应力触发作用，得出断层滑动模型对同震计算结果的影响集中在发震断层附近而对远场影响较小.  相似文献   

A SYSTEM OF CAPACITIVE HIGH-VOLTAGE PULSE RECHARGE/DISCHARGE AND ITS IMPLICATION ON EXPERIMENTALLY TRIGGERED EARTHQUAKE     

ZHANG Zhi-he  GUO Yan-shuang  CHEN Shun-yun 《地震地质》2018,40(6):1417-1426

An external small disturbance may trigger seismic events when the fault is in a critical state. The problems related with earthquakes triggered by the dynamic stress such as blasting loads, impact loads, volcanic eruptions and strong earthquakes, have usually drawn wide concerns in earthquake science, and the corresponding research contents are quite extensive, including earthquake triggering mechanisms, triggering earthquake uncertainty, aftershock triggering, and so on. Among them, experimental research is an important way to understand the stress triggering conditions and physical mechanisms, such as the influence of load disturbance on fault friction traits, the influence of periodic disturbance of tidal stress on fault instability, etc., all of which can be gained through experimental investigations. Among them, "how to trigger" is a basic scientific problem to increase the understanding of earthquake prediction theory, thus receiving more attention. There are also some studies that focus on "what happened after the trigger", that is, the sliding instability generated by the triggering method, and then the evolution characteristics of the sliding instability process. The well-known experimental study of the super-shear rupture process is conducted by using the electric explosion method to trigger the fault instability, and the high-speed camera records the super-shear rupture during the fault instability. This means that when the trigger source is controllable, it is possible to generate different types of instability processes, and then to explore which earthquakes will be triggered at different time and space positions under different stress states by means of active triggering. The study of stability analysis and instability process has important scientific significance.A stable system of capacitive high-voltage pulse discharge and recharge is one of basic techniques for studying the triggered earthquakes in laboratory. Based on the wire electric explosion method, this paper develops a controllable trigger experiment system. By designing a new capacitive high-voltage pulse charge and discharge system, while considering the actual needs of monitoring and system timing, multiple functions are integrated into one system. Functionally, in addition to realizing the dynamic loading and unloading function of the wire electric explosion method, the discharge process can be monitored, and the triggering, synchronization and timing signal output is performed with other observation systems, thus realizing the whole process monitoring of the dynamic disturbance action. After testing, the following functions are achieved:1)The voltage and current of the high-voltage charging power supply system can be automatically adjusted, and the system can be shut off after charging; 2)Control modes include manual and remote controls. These two modes can control the recharge, release and pulse discharge of the high voltage capacitor; 3)The system can produce multi-channel synchronous output, which satisfy multiple systems working together. In particular, the remote sensing method greatly improves the experimental maneuverability and security; 4)The system has multiple sets of gas discharge tube to trigger discharge, with a wide range of discharge voltage of 500~5 000V; 5)Roche coil resistance integral current detection can meet the transient resistance, large current detection. Test results indicate that this system has good repeatability and stability with the same discharge energy and discharge energy regulator, which is conducive to carry out single channel trigger of high-pressure discharge experiment. In short, the new charging and discharging system can meet the requirements of experimental study of triggering earthquake. In addition, this system can be used to generate the stress disturbance under certain static and dynamic conditions, and then judge whether this kind of mechanical conditions in active fault systems is currently stable.In short, a controllable single-shot discharge system is developed by a capacitive high-voltage pulse discharge system, which provides a good technical basis for experimental research on triggering earthquakes. In addition, the new system also has application significance:1)multiple triggering output can simultaneously start multiple systems and improve the efficiency of observation. Fault instability is a characteristic of transient response, so, its observation requires high-speed acquisition equipment, which is difficult to control on observation; the trigger system is controllable, with active synchronization observation using physical parameters; 2)stress disturbance can be triggered under static and dynamic loads to detect the safety and stability of the fault system with active trigger.  相似文献   

Relocation of the Jinghe MS6.6 Earthquake Sequence on August 9, 2017 and Analysis of the Seismogenic Structure     

Liu Jianming  Gao Rong  Wang Qiong  Nie Xiaohong 《中国地震研究》2018,32(4):482-490

Based on the digital waveforms of the Xinjiang Digital Seismic Network,the Jinghe M_S6.6 earthquake sequence( M_L≥1. 0) were relocated by HypoDD,The characteristics of the spatial distribution and the seismogenic structure of this earthquake sequence were analyzed. The results show that the main shock is relocated at 44. 2639° N,82. 8294° E,and the initial rupture depth is 17. 6 km. The earthquake sequence clearly demonstrates a unilateral extension of about 20 km in the EW direction,and is mainly located at a depth of 7km-17 km. The depth profile along the aftershock direction shows that the focal depth of aftershocks tend to be shallower within 10 km to the west of the main shock,the focal depth of the aftershock sequence with the tail direction deflecting SW is deeper. The depth profile perpendicular to the earthquake sequence shows a gradual deepening of the seismic sequence from north to south,which indicates that the fault plane is dipping south.According to the focal mechanism solution,given by the Institute of Geophysics,China Earthquake Administration,and the geological structure of the seismic source region,it is inferred that the seismogenic structure of the Jinghe M_S 6.6 earthquake may be the eastern segment of the Kusongmuxieke fault.  相似文献   

地震重灾区诱发次生地质灾害风险评价研究   总被引：6，自引：4，他引：2       下载免费PDF全文

李天华  袁永博 《地震工程学报》2018,40(1):111-115

为了揭示地震重灾区与次生地质灾害的关联性,以某地震灾区为例,在分析次生地质灾害类型与危害的基础上,通过计算一次泥石流总量及流量确定其危险度,并引入易损性指数,确定各评价单元次生山地灾害的易损性大小,设置评价指标;结合研究区实际,采用层次分析法构建次生地质灾害风险评价模型,对地震重灾区诱发次生地质灾害风险进行评价。实验以次生地质灾害中的泥石流产生的灾害风险为例进行研究,结果表明,采用本文研究方法可在有效确定地震重灾区诱发次生地质灾害的位置方面具有一定优势,但在纵向地震造成次生地质灾害风险评价方面需进一步进行研究。  相似文献   

福建仙游震群序列发震构造分析研究   总被引：1，自引：0，他引：1       下载免费PDF全文

秦双龙  邱毅 《地震工程学报》2018,40(6):1306-1311

福建仙游地区自2010年8月开始出现地震序列活动,2012年地震活动水平有所提高,2013年以来地震活动水平进一步提高,ML3.0以上地震集中活跃。福建数字化地震台网对这些地震进行了较完整的监测,记录到丰富的观测资料。通过利用P、S波到时数据对ML≥1.0地震序列进行重新定位,发现地震序列空间位置和震源深度呈现出不同的时段性分布特征。同时利用福建数字化地震台网记录到的波形资料,采用"剪切-粘贴"法,获取了ML≥3.5的震源机制解和最佳震源深度。通过震群序列活动特征、震源位置分布、震源区断层活动分布以及震源机制解特征综合判断认为:仙游震群序列为库水下渗促使断裂滑动引起的构造地震,属于水库诱发型构造型地震,发震构造为穿过库区的NW向石苍断裂。  相似文献   

TECTONIC INDICATIONS OF OCCURRENCE OF MODERATE-TO-STRONG EARTHQUAKES IN CHAOHU-TONGLING AREA,ANHUI PROVINCE     

GUO Peng  HAN Zhu-jun  ZHOU Ben-gang  ZHOU Qing  MAO Ze-bin 《地震地质》2018,40(4):832-849

The Chaohu-Tongling area in Anhui Province is a typical moderate-to-strong earthquake active area in the mainland of China. Four earthquakes occurred in this area, displayed as a NNE-trending zonal distribution, including the 1585 M5(3/4) Chaoxian earthquake and the 1654 M5(1/4) Lujiang earthquake, which formed a striking moderate-to-strong seismic activity zone. Field survey, shallow geophysical prospecting, drilling data, collection and dating of chronology samples and comprehensive analysis of fault activity indicate that the Fanshan, Xiajialing and Langcun faults are not active since Quaternary. The NNE-trending Tongling Fault is a buried middle-Pleistocene fault, but it can produce moderate-to-strong earthquakes and control the evolution and development of three en echelon geologic structures. The intensity of the four earthquakes is characterized by southward progressive decrease, which is in accordance with the characteristics that the subsidence range of Wuwei Basin is obviously larger than that of Guichi Basin to its south since late Cenozoic. In terms of deep structure, the characteristics of spatial distribution of Tongling Fault indicate that it corresponds to a NNE-striking Bouguer gravity anomaly gradient belt. So there is a spatial correspondence between the middle-Pleistocene Tongling Fault, the en echelon structures, the differential movement of the neotectonics, the Bouguer gravity anomaly gradient belt and the moderate-to-strong seismic activity belt in the Chaohu-Tongling area, indicating that they should be the tectonic indications of occurrence for moderate-to-strong earthquakes.  相似文献   

Analysis of Gravity Changes before and after the Akto MS6.7 Earthquake in 2016     

Ailixiati Yushan  Liu Daiqin  Li Jie  Li Rui  Abudutayier Yasen  Sun Xiaoxu  Zhu Zhiguo  Li Guirong  Chen Li 《中国地震研究》2018,32(3):377-387

This paper analyzes the characteristics of time sequence changes of gravity points near the epicenter, different changes of measuring lines and gravity changes of measuring areas in point-line-area manner respectively with the 5-period mobile gravity data through densified observation by the South Xinjiang Observation Network after the 2015-2016 Akto earthquake in Xinjiang. The gravity observation results before the earthquake indicate that the Wuqia-Bulungkol area near the epicenter presented the trend of gravity value increasing since 2015, but the gravity value decreased half a year before the earthquake, and witnessed a high gradient zone of gravity changes during some periods before the earthquake. The gravity observation results after the earthquake show that there is a trend of opposite changes in gravity difference on the northern and southern sides of Bulunkou, and good correspondence exists between the characteristics of gravity field changes near the epicenter before and after the earthquake and the geologic structure distribution in the area.  相似文献   

利用近场高频GPS、 强地面运动和远场地震波形数据联合反演2008年汶川M_S8.0地震的震源时空破裂过程     

孟国杰  苏小宁  王振  廖华 《地震》2018,38(2):11-27

联合近场GPS测站1-Hz运动学位移、 强震仪加速度波形和全球台站P震相波形作为约束, 以时空滑动分布约束条件和ABIC模型参数选择方法, 结合先验的滑动方向变化范围, 反演2008年汶川M_S8.0地震的震源时空破裂过程, 给出了能够综合反映震源破裂过程的统一模型。 结果表明, 汶川地震总体上存在4个主要的破裂区, 最主要的一个破裂区位于震源东北40~120 km, 断层面上的最大位错量约为10 m, 主体滑动分布在2~20 km深度范围, 破裂达到地表; 第二个主体破裂区位于断层破裂带南段, 最大滑动量达到6 m; 另外2个主体滑动区位于断层破裂带北段, 但滑动破裂量小于断层南段破裂区的滑动量, 滑动破裂值最大值为4 m, 超过1 m的区域在走向上超过70 km。 反演得到的断层滑动模型的地震矩为9.5×10²¹ Nm, 相应的矩震级为M_W7.95。 汶川地震破裂表现为单侧破裂, 起始破裂在汶川下方16 km深度, 向东北方向一致性地传播, 过程持续~120 s。 在地震发生后0~10 s内, 破裂集中在震源起始破裂区, 滑动破裂值为~1.0 m, 之后破裂向东北方向扩展, 震后20~40 s是主要的破裂时段。 在40~60 s, 破裂跨越断层南段和北段。 在80~90 s破裂最大值开始下降, 在100~110 s时, 下降为~0.5 m, 在110~120 s时, 下降为~0.1 m。 加入近场GPS测站1-Hz 波形数据与近场强震仪波形和远场长周期体波联合反演, 提高了震源破裂模型的空间分辨率, 特别是浅部滑动破裂区的分辨率, 反演的最大滑动破裂值比不用1-Hz 波形数据反演的结果增大, 表明近场1-Hz GPS波形数据对于揭示汶川地震的时空破裂过程具有重要的作用。  相似文献   

基于特大地震发生率的川滇地区地震危险性预测新模型          下载免费PDF全文

程佳  徐锡伟  陈桂华 《地球物理学报》2020,63(3):1170-1182

川滇地区是我国地震危险性较高的地区之一.本文基于对特大强震的风险性考虑,使用全球地震模型OpenQuake软件,建立了川滇地区地震危险性预测新模型.首先根据构造特征划分多个震源分区,并整理出这些震源分区内断层活动特征与滑动速率;基于震源分区和断层模型,使用GPS应变率转换成的锥形古登堡-里克特关系作为整个区域的地震积累率,并允许超过历史最大震级的特大地震的出现,结合活动断层滑动速率所积累的地震发生率,给出震源分区内断层地震源和背景地震源的地震发生率的比率分配关系;在活动断层分段上,保留了大型断裂或其主要部分,没有根据小的阶区来对断层进行详细分段,以便分配特大地震发生率;并使用地震率平滑方法分配背景地震发生率.最后在OpenQuake中加入地震动预测方程,计算出了川滇地区的PGA分布图,为区域地震危险性提供科学依据.  相似文献   

地震作用下深埋隧道围岩形变的数值模拟研究          下载免费PDF全文

吕燕霞  扶海鹰  郁章剑 《地震工程学报》2020,42(1):215-220

隧道围岩受地震荷载作用影响产生开裂变形,给交通、安全与经济带来极大影响,为提升隧道安全稳定性能,以某市隧道为对象,研究地震作用下深埋隧道围岩形变的数值模拟。综合考虑地震动作用与地震波扩散特性,利用FLAC软件构建三维动力模型;通过边界设置解决地震波反射问题,基于物理力学参数与地震荷载条件,通过相对变形法研究地震条件下深埋隧道围岩变形特性、能量聚集特性与安全性能。研究结果显示:深埋隧道围岩受地震荷载作用影响,形成挤让、椭圆化的变形走向;变形达到最高值时,应变能量密度高于2350 J/m^3的区域集中在隧道Ⅰ洞左侧围岩边墙和中夹岩柱上;各监测点安全系数呈非对称性,隧道右侧下角区域安全系数低于国家相关标准,计算结果与实际测量结果一致。  相似文献