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941.
The statistical technique known as analysis of variance is applied to a large set of European strong-motion data to investigate whether strong ground motions show a regional dependence. This question is important when selecting strong-motion records for the derivation of ground motion prediction equations and also when choosing strong-motion records from one geographical region for design purposes in another. Five regions with much strong-motion data (the Caucasus region, central Italy, Friuli, Greece and south Iceland) are investigated here. For the magnitude and distance range where there are overlapping data from the five areas (2.50 Ms 5.50, 0 d 35 km) and consequently analysis of variance can be performed, there is little evidence for a regional dependence of ground motions. There is a lack of data from moderate and large magnitude earthquakes (Ms > 5.5) so analysis of variance cannot be performed there. Since there is uncertainty regarding scaling ground motions from small to large magnitudes whether ground motions from large earthquakes are significantly different in different parts of Europe is not known. Analysis of variance has the ability to complement other techniques for the assessment of regional dependence of ground motions.  相似文献   
942.
A destructive earthquake of magnitude Mw = 6.8 hit the region of Boumerdes and Algiers (Algeria) on May 21, 2003. This is among the strongest seismic events of the mediterranean region and the most important event in the capital Algiers since 1716. It caused a widespread damage in the epicentral region, claimed 2271 human lives, injured 10000, about 20000 housing units affected and left about 160000 homeless. The main shock was felt about 250 km far from the epicenter and triggered sea waves of 1–3 m in amplitude in Balearic islands (Spain). Based on field observations and press report an intensity IX (MSK scale) is attributed to the epicentral area. The main shock was followed by many aftershocks among them several are of magnitude greater than 5.0, which added panic to inhabitants. The main shock triggered ground deformation, particularly liquefaction whose features are in different forms and sizes and caused damage and collapse of roads. The focal mechanism determined by worldwide institutions yield a pure reverse faulting with a compressional axis striking NE-SW. The epicenter is located offshore about 7 km from the Boumerdes-Dellys coast. Field observations show 0.7 m of coseismic uplift of shoreline between Boudouaou and Dellys. This uplift is about a half of the extracted coseismic slip from the seismic moment. On the other hand there is no clear surface break onshore, confirming hence, that the causative active fault is offshore. However, the rupture may propagate onshore to the SE near the Boudouaou region where ground cracks showing reverse faulting are observed a long a corridor of about 1 km wide. These fissures may correspond to a diffuse coseismic deformation.  相似文献   
943.
The characteristics of seismic ground motions in southern China are difficult to determine statistically due to a lack of strong ground motion data. In this study, a stochastic finite-fault ground motion model was adopted to simulate the seismic ground motions at bedrock for southern China, based on parameters derived from small and medium earthquakes that have occurred in the region. From these, the response spectra was estimated. A set of ground motion attenuation relations hipswas then developed based on simulated peak ground motions and response spectral parameters through regression, which would be applicable for use in engineering practice. Through comparisons, it was demonstrated that the proposed ground motion relationships are generally consistent with those obtained from other reported ground motion attenuation models for southern China.  相似文献   
944.
建筑结构抗震研究若干基本问题概述及讨论   总被引:3,自引:1,他引:2  
本文介绍和讨论了结构抗震研究中的一些基本问题,包括地震反应分析选择地面运动输入应注意的问题,高层结构地震模拟试验问题和结构地震反应分析中的主要分析方法和存在的问题,最后简要介绍了目前常用结构反应分析程序。  相似文献   
945.
关于下一代地震区划图编制原则与关键技术的初步探讨   总被引:22,自引:10,他引:12  
本文在回顾我国四代地震区划编图原则的基础上,结合对未来我国社会经济发展状况和国家地震安全政策变化的分析,同时对国际上地震区划研究进展与编图工作的现状了解,探讨了下一代地震区划编图的基本原则,提出了与之相关的基本科学技术问题,对第五代地震区划图的编制提出了初步的建议。  相似文献   
946.
“7·22”云南盐津地震房屋震害分析   总被引:2,自引:0,他引:2  
本文根据地震现场的考查情况,介绍了2006年7月22日云南盐津5.1级地震的灾害概况,归纳和分析了灾区生土墙结构、石结构、钢筋混凝土框架结构和木构架结构房屋的震害特征及其破坏原因,并对我国村镇房屋的防震减灾研究提出了若干建议。  相似文献   
947.
本文根据甘肃省农村社会经济发展和地震环境特征,简要分析了甘肃农村民居主要建筑结构类型和抗震性能,结合近10多年来破坏性地震资料,总结了农村民居主要震害特点,提出了实施甘肃省农村民居地震安全工程的对策与措施。  相似文献   
948.
In the Gawler Craton, the completeness of cover concealing the crystalline basement in the region of the giant Olympic Dam Cu–Au deposit has impeded any sufficient understanding of the crustal architecture and tectonic setting of its IOCG mineral-system. To circumvent this problem, deep seismic reflection data were recently acquired from  250 line-km of two intersecting traverses, centered on the Olympic Dam deposit. The data were recorded to 18 s TWT ( 55 km). The crust consists of Neoproterozoic cover, in places more than 5 km thick, over crystalline basement with the Moho at depths of 13–14 s TWT ( 40–42 km). The Olympic Dam deposit lies on the boundary between two distinct pieces of crust, one interpreted as the Archean–Paleoproterozoic core to the craton, the other as a Meso–Neoproterozoic mobile belt. The host to the deposit, a member of the  1590 Ma Hiltaba Suite of granites, is situated above a zone of reduced impedance contrast in the lower crust, which we interpret to be source-region for its  1000 °C magma. The crystalline basement is dominated by thrusts. This contrasts with widely held models for the tectonic setting of Olympic Dam, which predict extension associated with heat from the mantle producing the high temperatures required to generate the Hiltaba Suite granites implicated in mineralization. We use the seismic data to test four hypotheses for this heat-source: mantle underplating, a mantle-plume, lithospheric extension, and radioactive heating in the lower crust. We reject the first three hypotheses. The data cannot be used to reject or confirm the fourth hypothesis.  相似文献   
949.
Yu J. Gu   《Tectonophysics》2006,424(1-2):41-51
This paper investigates the shear velocity structure under the northern East Pacific Rise at the latitude range of 9–18°N, using intermediate-period Rayleigh and Love waves. The selected ocean-bottom seismic records provide source–receiver paths that ideally constrain the lithospheric mantle structure beneath the southern Rivera plate and the Mathematician paleoplate. The Rayleigh wave data infer a relatively thin ( 30 km) lithosphere under the eastern side of the present-day East Pacific Rise. The associated shear velocities are consistent with existing models of oceanic mantle beneath this region, and the estimated plate age of 2–3 million years agrees with results from magnetic dating. The west of the rise axis is characterized by a thicker and faster lithosphere than the eastern flank, and such structural differences suggest the presence of a relatively old Mathematician paleoplate. The discontinuous change in mantle structure across the East Pacific Rise spreading center are observed in both isotropic and anisotropic velocities. The young oceanic lithosphere east of the rise axis shows strong polarization anisotropy, where the dominant orientation of crystallographic axes roughly parallels the spreading direction. However, the western flank of the rise axis is approximately isotropic, and the lack of anisotropy suggests complex deformation mechanisms associated with earlier episodes of ridge segmentation, propagation and dual-spreading on and around the Mathematician paleoplate.  相似文献   
950.
遥感信源色彩信号的提取与复现   总被引:13,自引:13,他引:0  
陈春  王冬  马克玲 《测绘科学》2006,31(1):27-28
提出遥感信源色彩信号的提取及复现理论,给出了可操作的技术路线,设计了提取与复现程序,用MODIS(中等分辨率航天成像光谱仪)数据提取并复现了色彩信号,生成了色彩信号图像。未进行大气校正的色彩信号图像等效于太空对地摄影,从图像可看出,地物被笼罩在瑞利散射形成的蓝色“云雾”下。经瑞利散射纠正后的色彩信号图像接近于地面真彩色摄影,非专业人员能根据地物颜色及阴影判读出常见地物。理论可用于遥感信源地面真彩色图像重建、色彩信号不完整信源彩色仿真、航天对地真彩色摄影、信源质量评价。  相似文献   
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