Influence of the ground profile on the reduction of earthquake motion at the filled man-made islands in the Kobe harbor during the 1995 Hyogoken Nambu earthquake     

Tadahiro Fukusumi  Hitodhi Ozaki  Masao Koba   《Soil Dynamics and Earthquake Engineering》2002,22(9-12):893-899

During the 1995 Hyogoken Nambu earthquake in Kobe, the ground motion at the filled man-made islands in the Kobe harbor was not as severe as that at the mainland. The building damage was also less compared to that on the mainland. It was found by comparative study of earthquake records that the magnitude of acceleration response on the ground surface decreases at the islands as opposed to the mainland. One dimensional effective stress analysis is adopted in this study. Input data has been generated from test results, e.g. the SPT N-value by standard penetration test and shear wave velocity V_s by PS logging. Results obtained by the analyses showed good agreement with the observed records, which is an indication of the suitability of the adopted analysis procedure. From this study, the followings are concluded. By the increase of SPT N-value of the filled layers, liquefaction near ground surface is restrained and damage modes such as ejection of water and soil can be prevented. Since the ground profile at the islands is that considerably soft filled layer and marine clay layers, etc. are present and the thickness of the surface layer is large, the initial natural period of the ground is above 1 s and the natural period is elongated further under the earthquake excitation, which is deemed to be the principal reason for the reduction of the earthquake motion at the ground surface.  相似文献   

巴林左旗-阿鲁科尔沁旗5.9级地震余震序列精确定位及分布特征   总被引：1，自引：0，他引：1  

刘芳  曹井泉 《东北地震研究》2004,20(4):22-27

2003年8月16日内蒙古巴林左旗与阿鲁科尔沁旗间发生5．9级地震，使内蒙古东部地震活动再次进入活跃阶段。通过对巴林左旗-阿鲁科尔沁旗5．9级地震余震序列分析表明，序列的空间位置变化不太大，集中发生在较小的区域内，说明该震震源体较小。整个余震序列以NWW向条带分布为主，条带的走向与宏观烈度等值线长轴方向及震源机制B节面方向一致。ML≥3．0余震形成NW和NE两条相互垂直的条带，主震发生在NW条带的北西端。分析余震序列深度剖面图，说明NW向可能为此次地震的主破裂方向。  相似文献   

Reconstruction of Mechanical Principles of Zhang Heng's Seismoscope     

Feng Rui 《中国地震研究》2004,18(2):142-160

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Systematic Analysis Method of Shear-Wave Splitting：SAM Software System   总被引：8，自引：2，他引：8  

Gao Yuan 《中国地震研究》2004,18(4):365-372

In order to make a more effective use of the data from regional digital seismograph networks and to promote the study on shear wave splitting and its application to earthquake stressforecasting, SAM software system, i.e., the software on systematic analysis method of shear wave splitting has been developed. This paper introduces the design aims, system structure,function and characteristics about the SAM software system and shows some graphical interfaces of data input and result output. Lastly, it discusses preliminarily the study of shear wave splitting and its application to earthquake forecasting.  相似文献   

地震时空丛集程度的度量及震前异常特征初探          下载免费PDF全文

张晓东  江志萍 《地震工程学报》1996,18(3):37-41

从Ｍｏｒｉｓｈｉｔａ空间丛集度出发，定义出其时间丛集度的表达式，并计算了几次大震前空间丛集度Ｊｓ和时间丛集度Ｊｔ的时间扫描曲线。从计算结果分析，无论是空间丛集度Ｊｓ还是时间丛集度Ｊｔ在大震发生前大都会出现高值异常。将Ｊｓ和Ｊｔ做了对比，从而对Ｍｏｒｉｓｈｉｔａ指数的含义进行了探讨，分析了各自的优缺点。结果表明，Ｊｓ和Ｊｔ可以做为一项地震活动性指标引入到地震预报中来  相似文献   

甘肃礼县新生代玄武岩的特征及其与地震的关系   总被引：3，自引：0，他引：3  

邵顺妹  邹谨敞  谢原定  周建国 《高原地震》1995,(2)

本文对甘肃礼县新生代玄武岩及邻区超基性、基性岩的岩石特性进行了简要的叙述，并测定了它们的化学成分，同时还在１×１０３ＭＰａ高压下测定了它们的地震波速度。文中还对玄武岩的物源深度及其与地震的关系进行了探讨。  相似文献   

滑坡危险性分析中地震动的概率性估算及地震滑坡的危险性评判   总被引：5，自引：0，他引：5  

王赞军  江志萍  张家庆  辛莉 《高原地震》1998,(1)

论述了滑坡危险性分析中如何科学地估算地震力的问题。主要思路概括为：将滑坡体视为一个完整体系的结构物（或震动对象）,将滑坡场点视为一个工程场点,利用比较成熟的地震危险性概率分析方法计算滑坡体未来若干年内可能遭遇的不同超越概率水平下的地震峰值加速度,这种不确定性的地震加速度是由地震预报的不确定性带入的,由此计算地震力和惯性力。最后,对地震触发滑坡的机理展开讨论。  相似文献   

甘肃、宁夏和青海地区地震前兆的某些特征   总被引：2，自引：2，他引：2       下载免费PDF全文

赵和云  钱家栋  夏玉胜  毛可  梁子斌 《地震工程学报》1997,19(3):1-10

通过对甘肃，宁夏和青海三省（区）２０次地震的前兆异常进行统计分析，发现该地区地震争存在“地震异常范围小、异常幅度小，异常时间和地震活动周期和短”的区域特性。同时还发现甘，宁，青地区的地震前兆有以下５个方面的共性特征：（１）６级以上地震前都有空区出现，且不同震级的空区随富 近发震时间先后嵌套出呈，呈现了介质逐 硬化的过程。（２）多种前兆的趋势异常各具某种优势形态；（３）形变资料在大震前的反向（或加速  相似文献   

Current and Future Applications of 3-D Global Earth-Ionosphere Models Based on the Full-Vector Maxwell’s Equations FDTD Method     

Jamesina J. Simpson 《Surveys in Geophysics》2009,30(2):105-130

Advances in computing technologies in recent decades have provided a means of generating and performing highly sophisticated computational simulations of electromagnetic phenomena. In particular, just after the turn of the twenty-first century, improvements to computing infrastructures provided for the first time the opportunity to conduct advanced, high-resolution three-dimensional full-vector Maxwell’s equations investigations of electromagnetic propagation throughout the global Earth-ionosphere spherical volume. These models, based on the finite-difference time-domain (FDTD) method, are capable of including such details as the Earth’s topography and bathymetry, as well as arbitrary horizontal/vertical geometrical and electrical inhomogeneities and anisotropies of the ionosphere, lithosphere, and oceans. Studies at this level of detail simply are not achievable using analytical methods. The goal of this paper is to provide an historical overview and future prospectus of global FDTD computational research for both natural and man-made electromagnetic phenomena around the world. Current and future applications of global FDTD models relating to lightning sources and radiation, Schumann resonances, hypothesized earthquake precursors, remote sensing, and space weather are discussed.

Jamesina J. SimpsonEmail:

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地磁日变与地震活动关系的主成分分析——以日本岩手县北部6.1级地震为例   总被引：13，自引：7，他引：6       下载免费PDF全文

韩鹏  黄清华  修济刚 《地球物理学报》2009,52(6):1556-1563

本文提出了将主成分分析方法和地磁日变分析方法相结合以从较强干扰背景中提取相对较弱地震地磁信息的一种新思路.具体以1998年日本岩手县北部6.1级地震为例,选用三个地磁观测台资料进行研究.利用调和分析方法得到了各台基于多次谐波拟合的地磁日变曲线,在此基础上对各台的地磁日变形态进行了研究,发现距震中最近地磁台的日变形态在地震前大约两周出现了明显的异常,而其他两个距离震中相对较远的观测台日变形态基本正常.最后,将主成分分析方法应用于上述拟合地磁日变结果,得到了各主成分及其所占能量比的时间变化,结果表明在地震前两周左右第二主成分所占能量比显著增加,而且距离震中最近的台站的上述变化明显高于另两个较远的台站.上述结果表明地震前两周左右检测到的地磁日变异常可能与震中附近地下电阻率的变化或孕震过程中产生的电磁信号存在一定关系,相关研究结果有助于加深对地震电磁现象的认识和理解.  相似文献