赤峰--辽蒙交界地区地震活动性及平均波速比分析   总被引：1，自引：0，他引：1  

韩晓明  王鑫  郝美仙 《高原地震》2009,21(3):11-16

分析了赤峰地区地质构造特征、地球动力学环境、历史中强地震活动,表明该区域具备发生中强地震的构造条件;2008年以来的地震活动表明,辽蒙交界地区存在发生5级以上中强震的危险性,该地区的波速比震前异常能够为该地区的地震中期预测提供一定的判定依据。  相似文献   

基于性能的结构抗风设计理论框架   总被引：2，自引：0，他引：2  

周云  汪大洋  陈小兵 《地震学刊》2009,(3):244-251

提出了基于性能的结构抗风设计理论框架,将风压强度划分为4个设计风压等级（弱风压、中风压、强风压及超强风压）,将人体振动舒适度划分为6个等级（无振感、轻微振感、中等振感、烦恼、非常烦恼和无法忍受）、三种振动水平（与人的舒适感相关的振动水平、与人正常工作和操作有关的振动水平、与人的生理健康直接相关的振动水平）。结合不同类别建筑物的性能需求及人体振动舒适度的要求,将结构风振性能水准划分为4种状态（性能健康、性能亚健康、性能病态及性能丧失）,将结构风振性能目标划分为5个等级（A、B、C、D、E）。提出了结构抗风概念设计与计算分析的一般原则,给出了结构性能抗风安全性评价及社会经济评价基本内容的建议。  相似文献   

Broadband frequency-dependent amplification of seismic waves across Bucharest, Romania     

Henriette Sudhaus  Joachim Ritter 《Journal of Seismology》2009,13(4):479-497

The determination of seismic amplitude amplification is a fundamental contribution to seismic hazard assessment. While often only high-frequency amplitude variations (>1 Hz) are taken into account, we analyse broadband waveforms from 0.14 to 8.6 Hz using a temporary network of 32 stations in and around the earthquake-prone city of Bucharest. Spectral amplitudes are calculated with an adaptive multiple-taper approach. Across our network (aperture 25 km × 25 km), we find a systematic northwest/southeast-oriented structural influence on teleseismic P-wave amplitudes from 0.14 to 0.86 Hz that can be explained by constructive interference in the dipping Cenozoic sedimentary layers. For higher frequencies (1.4–8.75 Hz), more local site effects prevail and can be correlated partly among neighbouring stations. The transition between systematic and localised amplitude variations occurs at about 1 Hz.  相似文献   

Shear-wave splitting in the crust beneath the southeast Capital area of North China   总被引：1，自引：0，他引：1  

Jing Wu  Yuan Gao  Yun-Tai Chen 《Journal of Seismology》2009,13(2):277-286

This study focuses on the southeast Capital area of North China (38.5–39.85° N, 115.5–118.5° E). Shear-wave splitting parameters at 20 seismic stations are obtained by a systematic analysis method applied to data recorded by the Capital Area Seismograph Network (CASN) between the years 2002 and 2005. Although some differences in the results are observed, the average fast-wave polarization is N88.2° W ± 40.7° and the average normalized slow wave time delay is 3.55 ± 2.93 ms/km. The average polarization is consistent with the regional maximum horizontal compressive stress and also with the maximum principal strain derived from global positioning system measurements in North China. In spite of the uneven distribution of faults around the array stations that likely introduce some amount of scatter in the shear-wave splitting measurements, site-dependent polarizations of fast shear wave are clearly observed: in the northern half of the study area, the polarizations at CASN stations show E–W direction, whereas in the southern half the polarizations exhibit a variety of possible azimuths, thus suggesting dissimilar stress field and tectonic frame in both areas. Comparing the splitting results with those previously obtained in the northwest part of the region, we find a difference in polarization of about 20° between the southeast and northwest parts of the Capital area; also, in the southeast Capital area the average time delay is smaller than in the northwest Capital area, thus making clear that the magnitude of crustal seismic anisotropy is not the same in the two zones. Being the shear-wave splitting polarizations in the southeast Capital area, which lies on the basin, clearly different from the observed polarizations in the northwest Capital area, where uplifts and basin converge, it is quite evident that the shear-wave splitting results are consequence of the tectonics and stress field affecting the two regions.  相似文献   

Seismically reactivated Hattian slide in Kashmir, Northern Pakistan   总被引：2，自引：0，他引：2  

Jean F. Schneider 《Journal of Seismology》2009,13(3):387-398

The Pakistan 2005 earthquake, of magnitude 7.6, caused severe damage on landscape and infrastructure, in addition to numerous casualties. The event reactivated Hattian Slide, creating a rock avalanche in a location where earlier mass movements had happened already, as indicated by satellite imagery and ground investigation. The slide originated on Dana Hill, in the upper catchment area of Hattian on Karli Stream, a tributary of Jhelum River, Pakistan, and buried the hamlet Dandbeh and several farms nearby. A natural dam accumulated, impounding two lakes, the larger one threatening parts of downstream Hattian Village with flooding. An access road and artificial spillways needed to be constructed in very short time to minimize the flooding risk. As shown by this example, when pointing out the risk of large-scale damage to population and infrastructure by way of hazard indication maps of seismically active regions, and preparing for alleviation of that risk, it is advisable to consider the complete Holocene history of the slopes involved.  相似文献   

ICEARRAY: the first small-aperture, strong-motion array in Iceland     

Benedikt Halldorsson  Ragnar Sigbjornsson  Johannes Schweitzer 《Journal of Seismology》2009,13(1):173-178

A small-aperture, strong-motion array, the ICEARRAY, has been deployed in South Iceland, a region with a history of destructive earthquakes, some exceeding magnitude 7. The array’s purpose is: (1) monitoring future significant events in the region, (2) quantifying spatial variability of strong-motion over short distances and (3) shedding light on earthquake source processes. The number of array stations and their arrangement were based on an optimisation of the shape of the corresponding array transfer function (ATF). The optimal ICEARRAY configuration comprises 14 stations, has an aperture of ~1.9 km and a minimum interelement distance of ~50 m and possesses a near-azimuthally independent ATF with a sharp main lobe, negligible sidelobes and a wavenumber range of 1.5–24 rad/km. Accordingly, the ICEARRAY has the intended capabilities of capturing seismic waves in the frequency range of 1–20 Hz, which is of main interest to earthquake engineering and engineering seismology applications.  相似文献   

Seismic response of single-column bent on pile: evidence of beneficial role of pile and soil inelasticity   总被引：2，自引：2，他引：0  

Nikos Gerolymos  V. Drosos  G. Gazetas 《Bulletin of Earthquake Engineering》2009,7(2):547-573

While seismic codes do not allow plastic deformation of piles, the Kobe earthquake has shown that limited structural yielding and cracking of piles may not be always detrimental. As a first attempt to investigate the consequences of pile yielding in the response of a pile-column supported bridge structure, this paper explores the soil–pile-bridge pier interaction to seismic loading, with emphasis on structural nonlinearity. The pile–soil interaction is modeled through distributed nonlinear Winkler-type springs and dashpots. Numerical analysis is performed with a constitutive model (Gerolymos and Gazetas 2005a, Soils Found 45(3):147–159, Gerolymos and Gazetas 2005b, Soils Found 45(4):119–132, Gerolymos and Gazetas 2006a, Soil Dyn Earthq Eng 26(5):363–376) materialized in the OpenSees finite element code (Mazzoni et al. 2005, OpenSees command language manual, p 375) which can simulate: the nonlinear behaviour of both pile and soil; the possible separation and gapping between pile and soil; radiation damping; loss of stiffness and strength in pile and soil. The model is applied to the analysis of pile-column supported bridge structures, focusing on the influence of soil compliance, intensity of seismic excitation, pile diameter, above-ground height of the pile, and above or below ground development of plastic hinge, on key performance measures of the pier as is: the displacement (global) and curvature (local) ductility demands and the maximum drift ratio. It is shown that kinematic expressions for performance measure parameters may lead to erroneous results when soil-structure interaction is considered.  相似文献   

潮汐应力-应变对某些地震序列的调制触发   总被引：2，自引：1，他引：1  

黎凯武  江在森  申彤 《地震》2005,25(4):75-86

对1960年以来中国大陆浅源地震序列与潮汐应变的相关分析表明, 某些地区某些地震序列, 包括前震序列、 前震-主震序列、 前震-主震-余震序列和主震-余震序列明显受到潮汐应力-应变的调制触发。 如龙陵地震的前震-主震序列, 邢台地震的前震-主震-余震序列、 唐山地震的主震-余震序列等。 这些地震序列受到潮汐力调制触发的特征明显, 对地震预测有意义, 并作了具体的叙述。 同时对地震序列受调制触发的机理作了初步的探讨, 指出不同类型地震序列的调制触发特征与孕育系统地质构造, 地震震源岩石性质和区域构造应力场方向以及地震破裂机制有关, 对地震机理和预测的研究有一定意义。  相似文献   

数字地震台网大震前地脉动异常实时跟踪系统(RTTS)   总被引：1，自引：0，他引：1  

范叶萍  蒋秀琴  吴野  李强  杨红艳  宋绪友  王淑辉  石岩 《地震》2005,25(3):49-55

通过计算机对数字地震台网产出的大动态、 高分辨率、 高精度的地震波形数据进行的定时采集部分数据跟踪分析, 发现有些台站大震前地脉动波形的幅度和周期有明显异常变化, 实时捕捉这些异常信息, 把监测与预报研究相结合, 将为区域性地震预报提供比较可靠的实证前兆信息。  相似文献   

1970年以来东南沿海地震活动参数的定量时空差异性分析     

周峥嵘  杨马陵  林树  鲍挺 《华南地震》2005,25(1):8-16

1970年以来,东南沿海地区经历了第V个活跃幕(或轮回)的平静和活跃时段,通过分析研究这两个时段地震活动在时空强上的差异,定量提取其活动演化过程参量,为该区未来地震活动期判定提供相对定量的参考依据。  相似文献