Characteristics of coseismic water level changes at Tangshan well for the Wenchuan MS8.0 earthquake and its larger aftershocks

Coseismic water level changes which may have been induced by the Wenchuan M_S8.0 earthquake and its 15 larger aftershocks (M_S≥?5.4) have been observed at Tangshan well. We analyze the correlation between coseismic parameters (maximum amplitude, duration, coseismic step and the time when the coseismic reach its maximum amplitude) and earthquake parameters (magnitude, well-epicenter distance and depth), and then compare the time when the coseismic oscillation reaches its maximum amplitude with the seismogram from Douhe seismic station which is about 16.3 km away from Tangshan well. The analysis indicates that magnitude is the main factor influencing the induced coseismic water level changes, and that the well-epicenter distance and depth have less influence. M_S magnitude has the strongest correlation with the coseismic water level changes comparing to M_W and M_L magnitudes. There exists strong correlation between the maximum amplitude, step size and the oscillation duration. The water level oscillation and step are both caused by dynamic strain sourcing from seismic waves. Most of the times when the oscillations reach their maximum amplitudes are between S and Rayleigh waves. The coseismic water level changes are due to the co-effect of seismic waves and hydro-geological environments.     

Nonlinear seismic behaviour of wall-frame dual systems accounting for soil–structure interaction

The aim of this paper is to study the effects of soil–structure interaction on the seismic response of coupled wall-frame structures on pile foundations designed according to modern seismic provisions. The analysis methodology based on the substructure method is recalled focusing on the modelling of pile group foundations. The nonlinear inertial interaction analysis is performed in the time domain by using a finite element model of the superstructure. Suitable lumped parameter models are implemented to reproduce the frequency-dependent compliance of the soil-foundation systems. The effects of soil–structure interaction are evaluated by considering a realistic case study consisting of a 6-storey 4-bay wall-frame structure founded on piles. Different two-layered soil deposits are investigated by varying the layer thicknesses and properties. Artificial earthquakes are employed to simulate the earthquake input. Comparisons of the results obtained considering compliant base and fixed base models are presented by addressing the effects of soil–structure interaction on displacements, base shears, and ductility demand. The evolution of dissipative mechanisms and the relevant redistribution of shear between the wall and the frame are investigated by considering earthquakes with increasing intensity. Effects on the foundations are also shown by pointing out the importance of both kinematic and inertial interaction. Finally, the response of the structure to some real near-fault records is studied. Copyright © 2012 John Wiley & Sons, Ltd.     

"5.12"汶川大地震震中区映秀镇地震灾情及次生地质灾害遥感初步调查

"5.12"四川汶川8级大地震发生后,中国国土资源航空物探遥感中心立即采用"赛斯纳"高空遥感飞机,携带高清晰彩色数码相机及先进的POS系统,迅速获取了重灾区的航摄图像数据。本文以震中附近的映秀镇地区为例,简要介绍了以该高质量航摄数据为基础,采用数字滑坡技术,快速进行震后重灾区灾情及次生地质灾害遥感调查的成果。     

加勒比板块多学科研究综述及其对地震预测的启示

2010年1月12日海地M_W7.0地震打破了Enriquillo断层近240余年的地震平静期, 可能意味着加勒比地区新的活跃周期的到来。 本文通过收集该地区地质构造演化、 地球物理场、 发震构造、 震源物理、 运动学特征及应力场演化等方面的研究成果, 分析由于海地地震的发生所带来的区域地震危险性等相关认识的改变。 通过对多学科资料的梳理, 分析利用多学科研究成果开展加勒比地区地震危险性分析的基本思路, 以期为未来的中国大陆区域动力学模型构建、 地震预测预报研究提供基础参考。     

历史地震资料与地震的中长期预测

故障诊断模型的基本内容是根据动态系统的外部特征来判断系统内部是否发生故障及确定故障发生的部位、时间和大小。由于故障诊断技术在监测及诊断故障的思路上和地震预报有很多相似之处，因此，把故障诊断技术应用于地震预报是可行的。由于该模型与其他数学模型一样，需要有较多的学习过程，所以历史地震资料在该模型中有重要作用。而其中的鲁棒性故障诊断模型在抑制各子模型的个性，凸现其共性方面有其特有的性质，所以把它作为一种综合模型，能抑制各子模型的个性，突出在地震预测方面的共性，从而提高预测的精确性。本文根据一个实例，说明了这种综合性模型的可行性。在文章的最后，由信息量的分析，说明了模型的鲁棒性特征。     

高层建筑坍塌墙体修复施工安全管理定量化控制模型研究

为了确保震后高层建筑坍塌墙体修复工程的安全性,提出一种高层建筑震后坍塌墙体修复施工安全管理方法。结合主成分分析法与信息熵法对震后高层建筑坍塌墙体修复施工管理的控制特征量进行提取,确定模型评价指标权重;根据加权学习法对坍塌墙体修复的施工进行量化控制;通过灰阶量化评估进行约束参量分析,构建安全管理控制模型;采用管理因素模糊调度算法实现施工安全管理控制,并完成优化决策。通过仿真实验验证坍塌墙体修复施工管理控制的管理效益与累积评价百分率。分析结果表明,采用该方法进行震后高层建筑坍塌墙体修复施工管理控制的管理效益最高可达83.32%,累积管理效果回报率较高,累积评价百分率平均约为75%,能够有效提高施工过程的安全管理效能,确保施工安全。     

龙陵-瑞丽断裂北段晚第四纪活动性特征及强震复发间隔

野外地质地貌调查表明,龙陵-瑞丽断裂(南支)北段是以左旋走滑为主兼具一定正断分量的区域性活动断裂.断裂晚更新世以来的平均水平滑动速率为2.2mm/a,平均垂直滑动速率为0.6mm/a;全新世以来的平均水平滑动速率为1.8-3.0mm/a,平均垂直滑动速率为0.5mm/a.断裂在晚更新世以来的滑动速率在不同的时间尺度上变化不大,反映出该断裂晚更新世以来的活动强度比较稳定.利用Poisson模型、Lognormal模型、BPT模型三种概率模型计算获得未来50a强震发震概率分别是:6.32％、0.08％、0.05％;三种模型分别取权重0.28、0.36、0.36,获得龙陵-瑞丽断裂北段未来50a特征地震发震概率为1.82％.     

More Emission Cones: Multi-frequency Simulation of the Pulse Profiles of PSR J0437-4715

Pulsar radio emission beams have been studied observationally for a long time, and the suggestion is that they consist of the so-called core and conal components. To reproduce these components is a challenge for any emission model, and that the pulse profile of pulsars changes with frequency presents even a greater challenge. Assuming a local surface magnetic structure (to produce the core or central beam) and a global dipole magnetic field (to produce the conal beams), Gil & Krawczyk (1997) applied curvature radiation to the pulse profile simulation of PSR J0437-4715 (hereafter the GK model). Here we present an alternative multi-frequency simulation of the same profiles within the framework of the Inverse Compton Scattering (ICS) model. It is obtained from our simulation (1) that besides the core, the inner cone and the outer cone, there is an outer-outer cone; (2) that the emission components of the core and cones evolve strongly with frequency. Some important differences between the ICS model and the     

Simulation analyses of buildings damaged in the 1995 Kobe,Japan, earthquake considering soil–structure interaction

A series of studies was conducted on three buildings of steel reinforced concrete structures with RC shear walls damaged in the 1995 Hyogo-ken Nanbu earthquake. These buildings are located in an area where structural damage centred around. Two of these buildings suffered severe damage, while the third was not structurally damaged. Our studies deal with site inspections, including micro-tremor measurement of buildings, the evaluation of input motions, and the response analyses considering soil–structure interaction. The results of simulation analyses of the two severely damaged buildings correspond to their actual damage state. From the response analyses of the one slender building with no structural damage, it was concluded that uplifting is the main reason it did not suffer any structural damage. Through these studies, the importance of soil–structure interaction and effective input motion is fully understood. Copyright © 1999 John Wiley & Sons, Ltd.     

利用sPn震相计算九江-瑞昌地区地震的震源深度

近震震相sPn与Pn到时差与震中距无关,只与震源深度和地壳模型有关.应用此方法,计算了发生在九江-瑞昌地区两次地震的震源深度,结果表明,利用区域台网sPn-Pn的到时差确定地震震源深度较为可信.根据华南地区速度模型,建立了九江-瑞昌地区sPn与Pn到时差与震源深度便查表.