用地震断层陡坎的形态方程确定古地震事件的年代

通过对地震断层陡坎演为过程的分析，应用均匀物质扩散理论建立地震断层陡坎的形态方程，推断古地震断层陡坎的年龄，从而确定古地震事件的期次及年代。用该方法对二台活断层古地震断层陡坎进行计算，所得结果与用其它方法确定的古地震事件的期次及年代对应较好。     

断层形态与地震破坏的动态模拟

前言地震破坏的动态模拟是地震学研究的老课题 ,其本质就是研究弹性体力学的初期值和边界值。关键是它涉及了几个方面 :“如何解方程式——方法”;“如何给出作为初始条件、边界条件的摩擦定律”。根据上世纪 80年代有关摩擦定律的实验、理论研究方面的进展和 90年代通过地震波反演对震源图像的详细探明 ,由事先假设破坏的形态和运动的运动学模式的方式转向没有解析解的、破坏自发进行的方式 (即地震破坏过程非常复杂 ,很难从物理的、定量的角度对它加以解释 !)。这次 ,我们以断层附近的地震动为研究对象 ,观察它是为什么、怎么样产生破坏的…     

工程场地中活动断层和场地地震安全性评价

综述了工程场地地震安全性评价中活动断裂评价和场地评价的方法和步骤,指出了评价方法中存在的问题,并提出了解决方案。     

断层场地震害研究综述

本文介绍了国内外断层场地震害的研究现状和主要观点，指出了断层提高烈度的观点的片面性，阐述了我国地震考察中研究方法的创新和取得的主要研究结果，总结了断层场地的震害特征和非发震断层对震害无明显影响的主要结论。     

台湾集集7.6级地震车笼埔发震断层场地灾害综述

１９９９年９月集集（Ｍｗ７．６）地震,由于车笼埔地震断层猛烈地逆冲推挤作用,导致断层沿线地带产生剧烈的场地地震灾害、文中列举车笼埔断层活动引发场地地震灾害的情况,提出该类活断层下盘建筑物的安全距离不应少于３０００ｍ,上盘建筑物的安全距离不应少于５０００ｍ。     

断层场地地震反应特征研究

如何合理评价断层场地对地震动影响进而为重大工程抗震设计提供依据是当前急需解决但尚未解决好的工程场地问题。针对根据工程经验抽象出的8种设想断层场地模型，应用显式有限元模拟计算了脉冲P波、SV波倾斜入射下的地震反应。根据数值模拟结果，总结和给出了断层倾向、破碎带宽度、破碎带形态对地震动影响的初步定量规律。     

汶川特大地震汉源烈度异常原因的初步分析

远离震中的汉源县老县城在汶川大地震中遭到了严重震害,是Ⅵ度区内的唯一的Ⅷ度烈度异常区.汉源的地震烈度异常现象引起学术界的广泛关注.在汉源科学考察基础上,介绍了汉源震害情况,收集和整理了汉源县城及附近有关工程场地的强震和土体力学参数资料.通过背后山滑坡体有限元分析结果与汉源附近强震台记录的比较,从传递函数角度分析了背后山滑坡复活对烈度异常的影响,研究了汉源特殊土层结构对地震动的影响.结果表明,背后山滑坡的复活和特殊土层结构的放大作用等场地条件的影响是引起烈度异常的主要原因.所得结论对进一步分析汉源烈度异常的原因具有一定的参考价值.     

On the faults of western Hexi Corridor and its nearby regions, northwestern China:Thrust faults and strike-slip faults of Late Cenozoic

Introduction Hexi Corridor, a corridor extended over 1 000 km and with a strike of WNW-ESE, is locatedbetween Alxa uplift and northern Qilianshan Caledonian folding belt of northern Qinghai-Xizang(Tibet) Plateau (Figure 1). In the paper, we will discuss the regions between Altun fault and Yu-mushan of the western Hexi Corridor, where the climate is arid, which results in sparse vegetation,but abundant oil and gas resource, and being one of the most important petroleum industry base…     

Stress interactions between normal faults and adjacent strike-slip faults of 1997 Jiashi earthquake swarm

During a 4-month period starting from 21 January, 1997, an earthquake swarm of seven major events (Ms≥6.0) struck the Jiashi region at the northwestern corner of the Tarim Basin in Xinjiang,, China. Previous relocation studies suggested that these strong earthquakes had occurred along at least two parallel rupture zones. According to the relocated hypocenters and focal mechanisms of the events, we have constructed fault models for these seven earthquakes to calculate the Coulomb stress changes produced by each of these events. Furthermore, we extended our model calculations to include an ad- jacent 1996 Ms=6.9 Artushi earthquake, which occurred one year before the Jiashi earthquake swarm. Our calculations show that the Coulomb stress change caused by the preceding events was around 0.05 MPa at the hypocenter of the 4th event, and higher than 0.08 MPa at the hypocenters of the 2nd, 3rd, 5th and 6th events. Our results reveal a Coulomb stress interactive cycle of earthquake triggering between two adjacent normal and strike-slip faults.     

场地地震反应分析中侧向人工边界距离选取及影响因素分析

结合均匀场地模型和分层均匀场地模型,采用数值试验的方法研究了场地地震反应分析中侧向人工边界距离的选取问题。分析了各主要因素对人工边界距离选取的影响,得到了如下结论:单侧人工边界距离与土层深度之比L/h是影响人工边界距离选取的主要参数;随着侧向人工边界距离的增加,有限元模型的计算误差并不一直减小,在局部范围内,会出现计算误差随着边界距离的增加而增大的现象;场地硬度、阻尼比和激振频率等因素不会影响计算误差随边界距离的变化规律,但采用自由场边界时受输入地震动频谱特性的影响较为明显;对水平激振下的一维场地模型来说,采用结合自由度边界时所需边界距离最短,自由场边界次之,采用粘性边界达到收敛时所需边界距离最长;无论哪种边界条件,当边界距离大于某一范围后,都能得到稳定的计算结果;相对于均质场地模型来说,实际的分层均匀场地建模时可适当减小侧向人工边界距离。     

基于故障树分析的华北平原带地震空间分布函数的确定

应用故障树分析的方法,对华北平原地震带地震空间分布函数进行重新厘定。应用断层破裂长度与面波震级、地震矩、矩震级之间的关系公式确定华北平原带各潜在震源区的地质因子;应用最大似然法、贝叶斯预测方法和地震活动度方法确定各潜在震源区的因子;综合考虑各因子情况,建立动态概率安全性评价的空间分布函数故障树,计算得到华北平原带潜在震源区的空间分布函数,并由新的空间分布函数计算了实验场地的地震危险性。     

鲜水河断裂带的地震模拟

本文运用由弹簧—滑块模型来模拟走滑断层的地震活动,讨论了模型中断层强度、断层滑块间弹簧强度、滑块与驱动盘之间片簧强度、滑块摩擦力的影响,以及初始条件敏感性。并以我国最为典型的一条走滑断层———鲜水河断裂带为例,运用试错法调整模型参数以使发生的地震最大限度地逼近实际发生的地震,并利用最终结果讨论了鲜水河断裂带今后的活动性。     

工程场地断裂评价及对策研究

工程场地断裂的正确评价是确保工程顺利进行和安全运营的基本保证。结合建设中的宿迁三线船闸，通过资料分析、现场考察和地球物理勘探以及钻探等手段，对通过闸址区而直接影响船闸群安全的场地断裂进行了系统的分析和评价。并结合场地条件特点，提出了船闸抗震和抗场地断裂设计的若干对策。     

Coherency of rupture and seismic spectrum

In considering the seismic spectrum, one of the methods to incorporate irregularity of fault motion statistically is to introduce the concept of coherency of fracture. In a classic paper,Aki (1967) investigated the scaling law of seismic spectrum on the basis of a statistical model in which an exponentially decaying function is fitted to the autocorrelation function of the dislocation velocity. It is found, however, thatAki's model does not necessarily express irregular fault motion, but corresponds to a smooth dislocation. We show that an analytical function of dislocation velocity gives the same autocorrelation function and the same seismic spectrum as those ofAki's model. In actual fault motion, there is considerable evidence which indicates that the dislocation is not continuous and smooth over the whole fault plane, but is often segmented in several parts. In order to take into consideration this feature we introduce a generalized autocorrelation function of the dislocation velocity in which many coherent fractures smaller than the size of the fault dimension are included. It is shown that the more small-scale coherent fractures, the larger the seismic wave energy in the high frequency range.Kanamori andAllen (1986) showed that a large ratio of seismic wave energy relative to the seismic moment means a large effective stress drop. On the other hand, it is well known that when a fault plane is segmented in several parts, stress drop becomes large (e.g.,Madariaga, 1979;Rudnicki andKanamori, 1981). These two results are fused in our model, because we find that large seismic wave energy is obtained when the fault motion includes small-scale fractures.Kanamori andAllen (1986) also showed that there is a tendency for earthquakes with long repeat times to have a large effective stress drop. Our model implies that a fracture corresponding to earthquakes with long recurrence intervals is more complex, and the strength is large, as also suggested byCao andAki (1986) using a numerical simulation. It should be noted that to the zeroth order, an approximate scaling relation is observed among earthquakes, which means that a large earthquake consists of a relatively large-scale coherent fracture. This fact seems to suggest that the condition of occurrence of a large earthquake is related to the maturing of a source region in which a large coherent fracture becomes feasible.     

机器学习算法在发震构造形态特征及地震迁移规律研究中的应用前景

对发震构造形态特征和地震迁移规律的研究,有利于震情形势研判和震源物理的研究,也可为后期三维地壳介质结构建模提供数据支持.本研究结合大量中小地震的分布特征规律,利用机器学习的相关算法,提取断层形态特征和地震迁移规律.