Numerical simulation of dynamic Coulomb stress changes induced by M 6.5 earthquake in Wuding, Yunnan and its relationship with aftershocks     

Hu Xiong-lin  Wu Xiao-ping  Yang Run-hai  Fu Hong  Hu Jia-fu  Huang Yong 《地震学报(英文版)》2008,21(1):24-34

Based on the discrete wavenumber method, we calculate the fields of dynamic Coulomb rupture stress changes and static stress changes caused by M6.5 earthquake in Wuding, and study their relationship with the subsequent aftershocks. The results show that the spatial distribution patterns of the positive region of dynamic stress peak value and static stress peak value are similarly asymmetric, which are basically identical with distribution features of aftershock. The dynamic stress peak value and the static stress in the positive region are more than 0.1 MPa and 0.01 MPa of the triggering threshold, respectively, which indicates that the dynamic and static stresses are helpful for the occurrence of aftershock. This suggests that both influences of dynamic and static stresses should be considered other than only either of them when studying aftershock triggering in near field. Foundation item: National Natural Science Foundation of China (40364001) and Joint Seismological Science Foundation of China (605014).  相似文献   

银川地震台数字化重力资料映震情况分析     

吕俊强  李国斌  马禾青 《内陆地震》2008,22(2):182-187

介绍了银川地震臼重力观测情况。应用调和分析、潮汐变化、非潮汐变化及滤波等分析方法,对银川台GS15-NO215型重力仪2003～2007年的观测资料进行了处理,分析了银川台数字化重力资料的观测质量及年变周期的特点。总结了银川台重力数字化资料与周边地区地震活动的对应关系及其映震情况。  相似文献   

南北地震带北部5次（1561~1920年）M≥7级地震触发关系研究   总被引：7，自引：1，他引：6       下载免费PDF全文

韩竹军  董绍鹏  谢富仁  安艳芬 《地球物理学报》2008,51(6):1776-1784

以南北地震带北部的青藏高原东北边缘与华北构造区过渡部位为例,通过建立地震构造模型,计算静态库仑破裂应力改变量（ΔCFS）,研究了该区1561~1920年360年间5次M≥7级地震之间的触发过程.结果表明,在1561年罗山东麓7¹/₄级地震之后,下一次地震无一例外地发生在前面地震产生的应力触发区（ΔCFS>0）.在4条被触发的发震断裂中,有3条发震断裂的平均ΔCFS>0.2×10⁵ Pa,最大可达0.62×10⁵ Pa,超出目前普遍认为触发应力阀值（0.1×10⁵ Pa）.根据断裂库仑破裂应力变化量（ΔCFS）和构造应力累计率（δτ）,计算获得了下一次地震发生的提前量（ΔT）,地震活动提前量最大可以达到160a.在一条重要活动构造带或地区上,一次地震发生对下一次地震的触发缩短了地震重复发生所需要的累积时间,使得地震可以提前发生,这一方面使得某一特定的发震断裂在时间尺度表现出准周期性,另一方面使得空间上不同发震断裂的地震活动表现出丛集发生的现象.此项研究有助于认识断裂间相互作用特点、揭示地震丛集发生规律以及预测未来地震危险区.  相似文献   

防潮堤坝对山东昌邑滨海湿地植物及土壤性质的影响分析   总被引：2，自引：2，他引：0  

陈琤  刘玉虹  陆滢  王光美  张华 《海洋科学》2017,41(5):50-58

为研究防潮堤坝对滨海湿地植物及土壤性质的影响,本研究在昌邑国家级海洋生态特别保护区内,通过样线法进行野外调查采样,进行防潮堤坝内外土壤、植被以及两者之间联系的分析,研究了堤坝内外植被及土壤性质差异。结果表明:堤坝内外土壤、植被有一定的差异;堤坝外部土壤C、N、P含量小于堤坝内部,堤坝外部土壤盐度大于堤坝内部;堤坝外部是以盐地碱蓬(Suaeda salsa)和獐毛(Aeluropus sinensis)为主滨海湿地景观,堤坝内部则是以柽柳(Tamarix chinensis)为主的灌草丛景观;保护区内物种丰富度与土壤盐度值呈负相关关系,随着盐度的升高,堤坝外部物种丰富度低于堤坝内部;芦苇(Phragmites australis)体内TC、TN、TP及C︰N︰P与土壤C、N、P含量及C︰N︰P没有明显相关性,而柽柳体内N含量与土壤P含量呈明显负相关关系,说明木本植物比草本植物更加依赖土壤中营养元素的供给。  相似文献   

1989—1999大同地震序列的隐伏断层研究:库仑应力分析和余震JHD重定位          下载免费PDF全文

冯永革  王海洋  陈永顺  黄清华 《地球物理学报》2016,59(2):568-577

1989年到1999年,大同—阳高地区发生了一系列MS≥5的中强地震.本文基于前人对1989年三次MS≥5地震的震源机制反演的结果,通过建立不同断层模型,利用库仑应力方法,计算前震对于主震,以及前震和主震对于余震的库仑应力触发关系,提出了一种可能的破裂模型,即1989年前震沿北西西方向发生左旋破裂,之后主震和余震沿北北东方向发生右旋破裂.根据这种破裂模式计算得出,前震发生后,主震震源处的库仑应力增加了约2×105 Pa,余震震源处的库仑应力出现下降;主震发生后,余震处的库仑应力出现回升,最后余震处的库仑应力几乎没有变化.基于大同地震台网的近场观测数据,用JHD(Joint Hypocentral determination)定位方法,对1999年11月1日MS=5.6地震后一个月的余震进行重定位,得到一条走向118°,倾角85°的左旋走滑断层,余震的深度分布在5km至20km范围内,显示该断层是隐伏断层.另外提出对主震震中位置约10km的修正.本文对1989年三次MS≥5地震序列和1999年MS=5.6地震余震空间分布的研究揭示该地区存在两条活跃的共轭隐伏走滑断层(1989年主震的北北东方向和1999年地震的北西西方向),并且推断已知的大王村断裂和团堡断裂是地下这两条共轭的隐伏走滑断层构造/地震活动在地表的响应.  相似文献   

THE STATIC COULOMB STRESS CHANGE OF THE 2014 LUDIAN EARTHQUAKE AND ITS INFLUENCE ON THE AFTERSHOCKS AND SURROUNDING FAULTS          下载免费PDF全文

MIAO Miao  ZHU Shou-biao 《地震地质》2016,38(1):169-181

On Aug. 3rd, 2014, a M_S6.5 earthquake struck Ludian County, Yunnan Province. It is a typical left-lateral strike-slip event. With the purpose of understanding the influence of the Ludian earthquake, this paper firstly calculates the co-seismic Coulomb failure stress changes of the mainshock with the employment of the finite dislocation source model inversed by other researchers and studies the triggering effect to the aftershocks within a month. We find that 82.43% of the aftershocks are located in the Coulomb stress increasing area(ΔCFS>0.01MPa), therefore, most of the aftershocks are triggered by the mainshock. Then, regarding the surrounding active faults as the receive faults, the Coulomb stress changes of the mainshock are calculated to investigate the impact on the faults nearby. The result shows that only the northeast end of the west branch and northeast part of the east branch of Zhaotong-Ludian faults have been brought to failure. However, the other faults such as Daliangshan Fault, Lianfeng Fault, Zemuhe Fault, Xiaojiang Fault and Mabian-Yanjin Fault are unloaded after the Luidian event, so the possibility of future earthquake is decreased around these faults. Besides, when the optimal failure plane is chosen as the receive fault of the Coulomb stress changes, the Ludian earthquake always has good triggering effect to the aftershocks no matter which source models and effective friction coefficients are chosen.  相似文献   

Exploiting Maximum Entropy method and ASTER data for assessing debris flow and debris slide susceptibility for the Giampilieri catchment (north‐eastern Sicily,Italy)          下载免费PDF全文

Luigi Lombardo  Felix Bachofer  Mariaelena Cama  Michael Märker  Edoardo Rotigliano 《地球表面变化过程与地形》2016,41(12):1776-1789

This study aims at evaluating the performance of the Maximum Entropy method in assessing landslide susceptibility, exploiting topographic and multispectral remote sensing predictors. We selected the catchment of the Giampilieri stream, which is located in the north‐eastern sector of Sicily (southern Italy), as test site. On 1 October 2009, a storm rainfall triggered in this area hundreds of debris flow/avalanche phenomena causing extensive economical damage and loss of life. Within this area a presence‐only‐based statistical method was applied to obtain susceptibility models capable of distinguishing future activation sites of debris flow and debris slide, which where the main source of failure mechanisms for flow or avalanche type propagation. The set of predictors used in this experiment comprised primary and secondary topographic attributes, derived by processing a high resolution digital elevation model, CORINE land cover data and a set of vegetation and mineral indices obtained by processing multispectral ASTER images. All the selected data sources are dated before the disaster. A spatially random partition technique was adopted for validation, generating 50 replicates for each of the two considered movement typologies in order to assess accuracy, precision and reliability of the models. The debris slide and debris flow susceptibility models produced high performances with the first type being the best fit. The evaluation of the probability estimates around the mean value for each mapped pixel shows an inverted relation, with the most robust models corresponding to the debris flows. With respect to the role of each predictor within the modelling phase, debris flows appeared to be primarily controlled by topographic attributes whilst the debris slides were better explained by remotely sensed derived indices, particularly by the occurrence of previous wildfires across the slope. The overall excellent performances of the two models suggest promising perspectives for the application of presence‐only methods and remote sensing derived predictors. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

潮汐应力对滑坡的触发机制及与时间相关性探讨     

刘裕华  陈征宙  蒋鑫 《岩土力学》2012,33(Z1):175-182

已有的滑坡统计数据和研究成果显示,滑坡发生的时间具有明显的周期分布规律特征,除了与降雨季节相关的因素外,受日月引力潮的影响也较明显。从固体潮理论出发,推导简化弹性地球模型地表的潮汐应力表达式,阐述固体潮汐作为滑坡日周期因子对滑坡的影响。在安全系数表达式中考虑潮汐应力的作用,并从表达式中阐述潮汐应力触滑的机制,剖析潮汐应力触发滑坡机制。以1985年的湖北省秭归县新滩特大型滑坡作为算例,采用折线滑动为破坏模式,论述潮汐应力与时间的相关性,以及边坡稳定性安全系数与时间的相关关系。计算结果表明,潮汐应力与边坡安全系数随时间均呈明显日周期及半日周期变动,该边坡稳定性系数的极差与不考虑潮汐应力下的稳定性系数的比值达到3.4%;滑坡发生的时间与潮汐应力处于峰值的时间较为吻合,说明潮汐应力很可能是除降雨等主因之外的触发临界状态滑坡发生的另一因素。  相似文献   

1973~1976年四川松潘强震序列的应力触发过程   总被引：13，自引：6，他引：7       下载免费PDF全文

朱航  闻学泽 《地球物理学报》2009,52(4):994-1003

本文计算和研究了1973~1976年四川松潘4次强震组成的序列引起的库仑应力变化图像,分析了由该序列各次事件引起的近场应力变化及其与后续强震发生以及余震分布的关系,同时分析了该序列引起的远场应力变化与随后25年区域中-强地震活动的关系.结果显示：1973年8月11日松潘黄龙6.5级地震导致虎牙断裂带中段上库仑应力的显著增加并触发了1976年8月16日的7.2级地震;此后,又沿断层向南相继触发了1976年8月22日的6.7级地震和8月23日的7.2级地震.该序列的绝大多数余震主要发生在主震发震断层的近场库仑应力增加区.另外,在该强震序列发生后的25年中、在距该序列发震断层中部约200 km范围内,6次5.0~6.6级地震均发生在由该序列引起的远场、微量的库仑应力变化增加区中.  相似文献   

断-块模型中走滑型地震应力触发研究——以青藏高原北部几次强震为例   总被引：1，自引：0，他引：1       下载免费PDF全文

王凯英 《地球物理学报》2009,52(7):1776-1781

从发震断层与活动块体的分布关系出发,以青藏高原北部地区几次强震为例,研究了介质非连续的断－块构造模型中地震永久位移造成的区域断层静库仑应力变化．研究表明,在断块构造模型中,走滑型为主的地震位错引起的区域断层库仑应力变化在地震破裂面以外随距离衰减很快,影响范围仅为几十公里,和余震分布尺度相当;对有地表破裂数据的1937年M7.5花石峡地震、1997年M7.5玛尼地震和2001年M7.8可可西里地震的模拟结果显示,先前地震的断层位移在后续地震断层面所造成的库仑应力甚微,预示了远距离地震之间的静应力触发效应不明显．  相似文献