基于InSAR和远场地震波联合反演2008年MW6.3大柴旦地震震源破裂过程

利用InSAR同震形变升、降轨数据和远场地震波数据,基于均方根最小与标量地震矩最小双重约束下的模拟退火方法,联合反演2008年11月10日大柴旦M_W6.3地震震源破裂过程.结果表明,2008年大柴旦地震震源破裂过程整体表现为沿倾向方向从深部破裂起始点处向上往地表传播,且破裂未到达地表;在前7 s内,滑动沿西北和东南两个方向传播,7 s后主要沿东南方向传播,破裂过程时间持续约为11 s,同震滑动分布主要集中在地下10~20 km范围内,最大滑动量达-0.71 m;反演结果揭示本次地震为西南倾高角度兼具微量走滑分量的逆冲破裂事件,反演矩张量为3.96×10¹⁸N·m,矩震级约M_W6.37.通过大柴旦地震发震断层和破裂机制综合分析,初步判断发震断层为西南倾向的大柴旦—宗务隆山断裂.     

2009年7月9日姚安MS6.0地震破裂方向性研究

2009年7月9日19时19分,云南姚安发生M_S6.0地震。10日17：02、13日00：01又相继发生M_S5.2、M_S4.7地震。利用近震CAP方法反演震源机制解发现,此次地震震源破裂方式以走滑为主,主震震源机制解2个节面走向分别为203°、295°。已有的考察资料尚未显示活动,故难以确定实际发震面。为此,采用相对质心震中确定破裂方向性的方法,利用主震与参考地震之间的P波到时差和CAP反演输出的波形时移,计算得到姚安地震起始震中与质心震中间的差异,推断震源机制解中走向为295°的节面为实际发震面,并对定位误差、发震时刻不准确以及机制解差异等因素进行了分析,发现这些因素对确定发震断层影响不大。     

Study of the Evaluation Model of the Earthquake Influence Field in Yunnan

In this paper,we conducted a regression analysis of the intensity distribution data of 146 earthquakes( M ≥ 5. 0) which occurred in the period from 1900 to 2014. According to previous research,Yunnan is divided into 3 tectonic regions. Then we use the data of the isoseismic lines in these 3 regions to fit the intensity-attenuation model of each region.Since there were a few M ≥ 7. 0 earthquakes in this 114-year period,the fitted intensityattenuation model of the strong earthquakes would be random or uncertain. To solve this problem,we introduce the Rupture Scale relationship to limiting our fitted intensityattenuation model of strong earthquakes. We choose the empirical relationship of magnitude and rupture-scale,which was proposed by Li Zhonghua and Qin Jiazheng,to correct the size of the influence field estimated through our intensity-attenuation model.Comparing our intensity-attenuation models with the previous ones, we find that in a certain tectonic region,the intensity isoseismals estimated through our model have average minimum error with the real intensity isoseismal decided through field investigation.Therefore,it is more advisable to choose the small-scale zone for the intensity-attenuation evaluation.     

Anchors in sand bed: delineation of rupture surface

Anchors of very large uplift capacities are required to support offshore structures at great water depths. The capacities of plate and mushroom type anchors are generally estimated based on the shape of rupture surface. An attempt has been made in the present investigation to delineate the rupture surfaces of anchors embedded in submerged and dry sand beds at various depths. The results exhibited two different modes of failure depending on the embedment ratio, namely, shallow and deep anchor behaviour. The load–displacement curves exhibited three- and two-phase behaviours for shallow and deep anchors, respectively. Negative pore water pressures recorded in submerged sand also exhibited variation similar to that of pullout load versus anchor displacement.     

四川岷江断裂带北段的新活动、岷山断块的隆起及其与地震活动的关系

岷山断块由岷江断裂和虎牙断裂自西向东的推覆逆掩运动所形成 ,处于我国南北地震带的中段。受区域NWW向主压应力场的控制 ,岷江断裂带第四纪以来表现为明显的推覆逆掩运动并具有一定的左旋走滑分量 ,岷山断块则处于强烈的隆起抬升状态。航片解译及野外地质考察结果表明 ,岷江断裂带由数条次级断裂呈羽列组合而成 ,其中尕米寺 -川盘右阶羽列区的羽列距达3km ,控制了低序次的地震破裂单元。第四纪地貌发育过程及断错地貌研究结果表明 ,岷江断裂晚第四纪以来的平均垂直滑动速率为 0 37～ 0 53mm/a ,水平位错量与垂直位错量大致相当 ;岷山断块第四纪以来的平均隆起速率为 1 5mm/a左右。地震活动特征表明 ,该地区 6级以上强震丛集于强烈活动的断块边界断裂上 ,中强地震及小震发生在新构造隆起区及近东西向断裂带上 ,与断裂的活动性质具有密切的成因联系     

First-order rupture features of the 2011 MW 9.0 Tohoku (Japan) earthquake from surface waves

This study analyzed the rupture directivity of the 2011 Tohoku earthquake by using 100-s Rayleigh-wave travel-times, influenced by the finite source, to derive the fault parameters of the earthquake. The results demonstrated that the earthquake exhibited a slow rupture propagation with a rupture velocity of approximately 1.5–2.0 km/s and asymmetric bilateral faulting. The two rupture directions were N60°E and N127°E, with rupture lengths of approximately 276 km and 231 km, respectively. The rupture toward N60°E had a source duration of approximately 183 s, longer than that toward N127°E (approximately 156 s). Overall, the entire source duration of the earthquake faulting lasted approximately 183 s. Regarding historical seismicity in eastern Japan, the 2011 Tohoku earthquake not only ruptured a locked area in which large earthquakes have rarely occurred, but also ruptured the source regions of several historical earthquakes. With the exception of its slow rupture velocity and generation of a tsunami, the rupture features of the 2011 Tohoku earthquake were inconsistent with those of typical tsunami earthquakes.     

The evolution of Petrov lake and moraine dam rupture risk (Tien-Shan,Kyrgyzstan)

An interdisciplinary study of glacier-related hazards in the Petrov lake region (Ak-Shiirak Range, the Inner Tien-Shan, Kyrgyzstan) has been undertaken to identify potential dangers to the area. A cooperative effort from experts in the fields of hydrology, glaciology, geomorphology and geophysics has been employed in this study. For the hazard assessment, evolution of the Petrov glacier and lake was reconstructed using historical reports, aerial photographs and satellite images. Geomorphological mapping and geophysical soundings was applied to the lake territory and the moraine dam. This has identified potentially hazardous areas of the dam including subsurface drainage zones and cracks that could cause a sudden extremely high discharge. In the past three decades, the Petrov lake has doubled in size, while in recent years, its area has been increasing by more than 92,000 square metres per year. Although there is no evidence for an imminent outburst, the dramatic increase in the lake’s size emphasizes the importance of this study.     

2001年8.1级昆仑山大震破裂过程及对2008年汶川8.0级大震孕育发生影响的研究

本文用三维流变非连续变形(块体边界)与有限元(块体内)相结合(DDA+FEM)的方法,在青藏高原及其东侧四川盆地,鄂尔多斯块体地区三维构造块体相互制约的大环境中,考虑了龙门山断裂带东西两侧地势、地壳厚度和分层的明显变化,及断裂带东侧四川盆地及鄂尔多斯块体坚硬地壳阻挡的影响,通过用GPS资料做位移速率边界约束和震源机制约...     

2008年汶川地震的破裂模型及引起的余震活动分析

用两种发震构造的破裂位移分布模型对2008年汶川地震造成的区域主要断裂的库仑应力变化进行了模拟.通过对这两种破裂位移模型模拟结果的对比分析,表明破裂位移模型的逆冲兼右旋滑动的位移模式及南北两段分别有两个滑动量高值区这样的特点控制了区域库仑应力变化的总体分布特征.汶川地震的余震分布和计算结果还显示:所获得的区域主要断裂的...     

关于三轴试验破裂角的试验论证与探讨

目前不同排水条件下的三轴试验中试样的剪切破裂角的计算方法存在用有效应力内摩擦角还是用总应力内摩擦角计算的争议。本文首先通过三轴UU、CU及CD试验对破裂角与内摩擦角之间的关系进行了论证,然后展开理论分析与探讨,并对三轴试验强度包线的确定存在的问题进行了讨论。结果表明:同一饱和土样在不同类型的三轴试验中破裂角与由有效应力指标计算的破裂角基本相等,试样的破裂角应由有效应力强度指标确定;三轴UU试验采用最大剪应力作为不排水强度是偏危险的,CU试验采用总应力摩尔圆公切线确定的强度参数与用实际剪切面确定的参数差别较小。