Strong ground motion prediction using macro–micro analysis method

The authors propose a new analysis method, called the macro–micro analysis method (MMAM) in a companion paper. (Earthquake Engng. Struct. Dyn., this issue) for strong motion prediction with higher resolution and accuracy. The MMAM takes advantage of the bounding medium theory to obtain optimistic and pessimistic estimates of the expected strong motion and the singular perturbation expansion that leads to an efficient multi‐scale analysis. The results of the numerical simulation with the MMAM are given as the sum of waves of low resolution covering the whole city and waves of high resolution for each part of the city. While the huge computation amount is reduced by the MMAM, the computation amount is huge still. For resolving this problem, this paper applies the finite element method with voxel element to numerical simulation tools after some numerical verification. To reproduce complicated material properties of surface soft deposits, fundamental hysteresis attenuation is implemented in the three‐dimensional simulation code. The proposed method is verified by carrying out the strong motion prediction with MMAM and comparing with measured data. In addition, the effect of three‐dimensional soil–structure and frequency component on the maximum velocity distribution, which is simulated by proposed method with high spatial resolution, is discussed. Copyright © 2005 John Wiley & Sons, Ltd.     

Macro–micro analysis method for wave propagation in stochastic media

This paper presents a new analysis method, called macro–micro analysis method (MMAM) for numerical simulation of wave propagation in stochastic media, which could be used to predict distribution of earthquake strong motion with high accuracy and spatial resolution. This MMAM takes advantage of the bounding medium theory (BMT) and the singular perturbation expansion (SPE). BMT can resolve uncertainty of soil and crust structures by obtaining optimistic and pessimistic estimates of expected strong motion distribution. SPE leads to efficient multi‐scale analysis for reducing a huge amount of computation. The MMAM solution is given as the sum of waves of low resolution covering a whole city and waves of high resolution for each city portion. This paper presents BMT and SPE along with the formulation of MMAM for wave propagation in three‐dimensional elastic media. Application examples are presented to verify the validity of the MMAM and demonstrate potential usefulness of this approach. In a companion paper (Earthquake Engng. Struct. Dyn., this issue) application examples of earthquake strong motion prediction are also presented. Copyright © 2005 John Wiley & Sons, Ltd.     

海城大震对我们预测思维的启示

1975年海城大震表现出的现象启发我们进行了不少地震预测模型和预测指标的研究,本文对组合模式的前兆时空分布、垂直运动在发震中的作用、调制模式以及穴位理论等作了概括介绍。     

北京地区近断层强地震动模拟

文中利用1679年三河-平谷8级地震的有关资料和北京地区地下三维结构的研究成果,建立了相应的震源模型和传播介质模型。利用Graves的三维有限差分程序,计算了北京地区震后的地面峰值速度。通过对计算结果的分析处理,获得了近断层强地震动的近断层效应、方向性效应、上盘效应和盆地效应等基本特征。同时,这些特征也反映了我们所设定的震源和传播介质参数的合理性,以及模拟方法的正确性。另外,分析处理中所获得的这些结果可为北京地区的城市规划和抗震设防提供客观的参考依据     

应力场演化与强震间相互作用的有限元模拟研究

针对川滇地区,在大量搜集前人资料和结果的基础上,建立了包括上地壳、中地壳、下地壳、上地幔等4层结构的三维有限元模型。通过反复调试,确定了其边界条件。然后计算了川滇地区背景应力场、断层蠕动产生的应力场和强震触发的应力场,以及它们的动态变化。结果表明后续地震大多发生在前面地震引发的库仑破裂应力正值区,前一地震对后续地震有一定的触发作用,强震是在较高的应力背景下成组发生的。这对判断、识别地震异常,提高地震预测水平有着很大的意义。     

强磁扰对视电阻率观测的影响

基于地球天然交变电磁场的基本理论,研究了磁静日、磁暴时的视电阻率的变化特征。结果显示：磁暴时ρｓ有明显变化,一般大于或等于２倍的磁静日的标准差。同时发现,由于地下介质的不均匀性,天然交变电磁场各种频率成份对地下电性介质的贡献不同,集肤效果也不同,从而使得在同一地电台、相同观测环境、相同观测条件下,磁暴时地电阻率的测道的差异,其干扰水平显著出明显的方向性。最后对研究中所发现的一些问题尽可能地给予了物     

1997年1月21日～4月16日新疆伽师强震群综述

１９９７年１月２１日～４月１６日,新疆伽师相继发生了７次Ｍ≥６的地震,造成了破坏与伤亡。该文就伽师强震群进行了综述,包括：地震类型和地震参数;震源机制;伽师地震的临震预报;地震现场工作等。     

An analysis of anomalous weather and cli mate around the M S= 6.2 earthquake of Zhangbei region

ＩｎｔｒｏｄｕｃｔｉｏｎＡｔｅｉｇｈｔｔｏｔｗｅｌｖｅｏ′ｃｌｏｃｋｏｎＪａｎｕａｒｙ１０,１９９８,ｔｈｅｒｅｏｃｃｕｒｅｄａｓｔｒｏｎｇｅａｒｔｈｑｕａｋｅｏｆＭＳ＝６．２ａｔＺｈａｎｇｂｅｉＣｏｕｎｔｙｉｎｔｈｅｎｏｒｔｈｗｅｓｔｅｒｎｐａｒ...     

康定—泸定地区地震对策及破坏性地震应急反应预案

康定—泸定地区地震对策及破坏性地震应急反应预案余河生（甘孜州地震局）杜江（泸定县地震办公室）康定—泸定地区由于所处的特殊的地震构造和地震活动环境而面临严峻的地震形势。为了做好地震应急工作,甘孜州地震局和泸定县地震办公室分别代政府制定了破坏性地震应急反...     

高强混凝土桩中坍落度的选取与应用

叙述了高强混凝土在桩基工程中的实际应用,提出了桩基混凝土试配当中与一般混凝土试配的不同之处及试配的方法与具体应用。