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701.
Mihailo D. Trifunac Maria I. Todorovska 《Soil Dynamics and Earthquake Engineering》2004,24(3):225-239
This paper compares the distribution of damage from the San Fernando, 1971, and Northridge, 1994, earthquakes. Both events had similar size, occurred on blind thrust faults beneath the densely populated San Fernando Valley of the Los Angeles metropolitan area, and hence offer a rare opportunity to compare the effects of the two earthquakes. In a previous study of the distribution of red-tagged (‘unsafe’) buildings and of breaks in the water distribution system caused by the Northridge earthquake, the authors discovered that buildings were damaged less where the soil response was not linear (as indicated by the breaks in the water pipes), except in localized areas of very severe shaking (peak ground velocity exceeding 150 cm/s). The study in this paper shows that the same applies to the damage caused by the San Fernando earthquake, and that the areas with severely damaged buildings (so called ‘gray zones’) for both earthquakes overlapped. This reoccurrence of damage within the same area is interpreted to result from some specific properties of local soil and geology. These properties are not fully understood at present, but should be explored to provide a basis for a new tool for forecasting microzonation maps, and reducing future seismic hazard. 相似文献
702.
Juin-Fu Chai Tsung-Jen Teng Chin-Hsiung Loh 《Soil Dynamics and Earthquake Engineering》2004,24(7):527-536
The objective of this paper is to identify the first mode ground period Tg, at each interesting site along Taiwan High Speed Rail (THSR) route, and further, to determine the site-dependent design response spectrum for particular sites with Tg larger than 1 s. In this paper, a linear model of shear wave propagating in a multi-layered half-space is developed to identify the first mode ground period Tg of an interesting site on the basis of the field bore hole data. Furthermore, for each one of the strong ground motion observation stations within the Chiayi-Tainan area, the first mode ground period Tg was identified by either coda waves or pre-event ambient vibrations from the seismograms. In addition, the site-specific parameter Cv in defining the normalized response spectrum was also determined based on the observed strong ground motions at the specified observation station, and hence the empirical function between Tg and Cv can be regressed for this interesting area. Therefore, for a particular site along THSR route within the Chiayi-Tainan area, the site-specific parameter Cv can be determined from the regressed empirical function by the identified first mode ground period Tg, and further, used to develop the site-dependent design response spectrum. 相似文献
703.
704.
一次沙尘暴过程锋生函数和地表热通量的数值诊断 总被引:7,自引:12,他引:7
沙尘暴是我国西北地区春季常发生的一种灾害性天气现象。本文利用国家气象中心改进的PSU/NCAR的非静力中尺度模式MM5,对1995年5月16日我国西北地区发生的一次沙尘暴天气个例进行了锋生函数和地表热通量的诊断分析。结果表明,沙尘暴过程是冷锋在移至我国西北地区时产生的一种强烈锋生过程;地表感热通量明显大于地表潜热通量;有无地面热通量对比试验表明,热力因子在沙尘暴产生过程中具有重要作用。 相似文献
705.
Turkey was struck by two major events on August 17th and November 12th, 1999. Named Kocaeli (Mw=7.4) and Düzce (Mw=7.2) earthquakes, respectively, the two earthquakes provided the most extensive strong ground motion data set ever recorded in Turkey. The strong motion stations operated by the General Directorate of Disaster Affairs, the Kandilli Observatory and Earthquake Research Institute of Bogazici University and Istanbul Technical University have produced at least 27 strong motion records for the Kocaeli earthquake within 200 km of the fault. Kocaeli earthquake has generated six motions within 20 km of the fault adding significantly to the near-field database of ground motions for Mw>=7.0 strike–slip earthquakes. The paper discusses available strong motion data, studies their attenuation characteristics, analyses time domain, as well as spectral properties such as spectral accelerations with special emphasis on fault normal and fault parallel components and the elastic attenuation parameter, kappa. A simulation of the Kocaeli earthquake using code FINSIM is also presented. 相似文献
706.
2001年昆仑山8.1级大震及其趋势研究 总被引:5,自引:0,他引:5
通过对1996-2001年我国西部强震活动在时空上的有序特征及其与台湾强震之间关联性的研究,分析讨论了2001年昆仑山8.1级大震的重要意义。同时根据有序性分析对青藏块体北部地区未来7级强震趋势进行了预测。 相似文献
707.
A set of acceleration source spectra is constructed using the observed parameters of the specific barrier model of Papageorgiou and Aki. The spectra show a significant departure from the 2-model at the high frequency range. Specifically, the high frequency spectral amplitudes of seismic excitation are higher as compared to the level predicted by the 2-model. This is also supported by other observational evidence. The high frequency amplitudes of acceleration scale proportionally to the square root of the rupture areaS, to the rupture spreading velocityv, and to the local strain drop (/) (=strain drop in between barriers). The local strain drop in between barriers is not related in a simple way to the global strain drop, which is the strain drop estimated by assuming that it is uniform over the entire rupture area. Consequently, the similarity law does not apply. Using the source spectra which we constructed, we derive expressions for high frequency amplitudes of acceleration such asa
rms anda
max. Close to the fault both are independent of fault dimensions and scale as (/µ)(f)1/2, while away from the fault plane they scale asW
1/2(/µ)(f)1/2, whereW is the width of the fault and f is the effective bandwidth of the spectra. 相似文献
708.
中国大陆及邻区Ms≥7.0级地震的相关与应用探讨 总被引:2,自引:0,他引:2
通过1976 ̄1988年中国大陆及邻区两组Ms≥7.0级地震活动实例,借助于全国震情网络的时段预报和强震活动空间的对称韵规律模式对本区大地震的时、空相关性进行实际应用的探讨后提出了我国大陆及边邻三大“地震进口窗”和我国内陆区域性的“地震进出口窗”的实用意义,长期为我国大形势预报及对华北地震的活动性估计提供有益的参考,并对该作法的物理意义进行了初步探讨。 相似文献
709.
710.