Design Earthquakes in the U.K.     

R.M.W. Musson 《Bulletin of Earthquake Engineering》2004,2(1):101-112

Three sites in the UK are taken, representative of low, medium and high hazard levels (by UK standards). For each site, the hazard value at 10⁻⁴ annual probability is computed using a generic seismic source model, and a variety of ground motion parameters: peak ground acceleration (PGA), spectral acceleration at 10 Hz and 1 Hz, and intensity. Disaggregation is used to determine the nature of the earthquakes most likely to generate these hazard values. It is found (as might be expected) that the populations are quite different according to which ground motion parameter is used. When PGA is used, the result is a rather flat magnitude distribution with a tendency to low magnitude events (\le 4.5 ML) which are probably not really hazardous. Hazard-consistent scenario earthquakes computed using intensity are found to be in the range 5.8–5.9 ML, which is more in accord with the type of earthquake that one expects to be a worst-case event in the UK. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Analysis of crack movements observed in an alpine bedrock cliff     

Mamoru Ishikawa  Yoshimasa Kurashige  Kazuomi Hirakawa 《地球表面变化过程与地形》2004,29(7):883-891

Crack widths and rock temperatures were monitored on an andestic bedrock cliff in the summit area of the Daisetsu Mountains, Hokkaido, northern Japan. Sequential data recorded the gradual widening of a crack to the point of critical crack extension, which resulted in catastrophic rock breakage. The data indicate that a combination of liquid water in?ltration into crack tip and subsequent freezing is the most signi?cant factor contributing to critical crack extension. The recorded sub‐critical crack movements involved a number of minor crack extensions and contractions, the timing of which correlates well with the magnitude of the reconstructed thermal stresses at the crack tip derived from thermal deformation of the plate‐shaped rock fragment. Larger crack extensions occurred when stress at the crack tip exceeded a threshold value, possibly re?ecting the control of rock fracture mechanics by which cracks are thought to propagate when the stress intensity factor at the crack tip exceeds the threshold values for stress corrosion cracking and the fracture toughness of the material. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

ENSO事件与鲁西北夏季降水的关系     

于凤英  张国胜 《山东气象》2004,24(1):13-15

应用近百年ENSO事件的研究成果和ENSO事件影响年的资料，统计分析近50年来ENSO事件与鲁西北夏季降水关系，为短期气候预测和汛期气象服务提供参考依据。  相似文献   

2002年我国沙尘暴天气特征分析   总被引：5，自引：1，他引：5  

牛若芸  薛建军  周自江 《南京气象学院学报》2004,27(2):178-184

利用逐日8个时次地面天气报告资料，分析了2002年全国沙尘暴的时空分布特征。结果表明：2002年出现的12次沙尘暴过程以3月18～22日的强沙尘暴过程影响范围最广、强度最强；我国北方地区浑善达克沙地及其周边地区的沙尘暴日数最多。另外，2002年我国沙尘暴高频期集中、早春多于晚春。主要原因是前期北方持续气温偏高、降水偏少，3—4月上中旬影响我国的冷空气十分频繁且强度较强，4月下旬—5月上旬我国北方地区出现了几次较大范围降水，5月中下旬影响我国的冷空气势力较弱且位置偏东。  相似文献   

高速公路沿线暗浜填土的勘察和评价     

项培林  沈日庚 《上海国土资源》2004,(3):6-8,37

目前，线路勘探中对浜填土检测不够重视或缺乏有效的方法，使浜填土的处理缺乏针对性，造成不必要的浪费或工程隐患。该文探讨了在线路勘探中暗浜的勘查技术及相应评价与整治方法。  相似文献   

天津泰达地区粉土振动液化特性的研究     

李平  纪真平  赵占久 《水文地质工程地质》2004,31(5):84-87

本文以动三轴试验和原位测试数据为基础，以天津地区砂性土为例，探讨砂性土振动液化机理及孔隙水压力变化规律，采用多种方法分析判别砂性土液化，为高烈度地区重要工程建筑抗震设计提供重要数据。  相似文献   

Simulation of Orissa Super Cyclone (1999) using PSU/NCAR Mesoscale Model     

U. C. Mohanty  M. Mandal  S. Raman 《Natural Hazards》2004,31(2):373-390

In this study a non-hydrostatic version of Penn State University (PSU) -- NationalCenter for Atmospheric Research (NCAR) mesoscale model is used to simulate thesuper cyclonic storm that crossed Orissa coast on 29 October 1999. The model isintegrated up to 123 h for producing 5-day forecast of the storm. Several importantfields including sea level pressure, horizontal wind and rainfall are compared with theverification analysis/observation to examine the performance of the model. The modelsimulated track of the cyclone is compared with the best-fit track obtained from IndiaMeteorological Department (IMD) and the track obtained from NCEP/NCAR reanalysis. The model is found to perform reasonably well in simulating the track and in particular, the intensity of the storm.  相似文献   

新疆阿克苏地区耕地变化分析及驱动因子研究   总被引：8，自引：4，他引：8  

张勇  刘时银  王建  韩海东  谢昌卫 《干旱区地理》2004,27(2):228-233

据新疆阿克苏地区各市、县的统计数据，分析了阿克苏地区50年代以来耕地面积的总体变化趋势、变化速度、区域差异和驱动因子。分析表明：阿克苏地区的耕地面积呈现波动增加的态势，但人均耕地面积经历了从增加到减少的变化过程；耕地空间变化区域差异较明显；影响阿克苏地区耕地变化的8个因子可归纳为经济发展因素、人类行为因素和城市化发展水平；通过模型计算，人类行为对耕地变化的影响尤其显著。研究结果和分析结论对于阿克苏地区农业可持续发展具有重要的意义。  相似文献   

基于数据融合的侧扫声纳图像预处理     

阳凡林  刘经南  赵建虎 《武汉大学学报(信息科学版)》2004,29(5):402-406

论述了基于数据融合的侧扫声纳图像处理的特殊过程。根据现代侧扫声纳系统的特点，提出了利用声线跟踪法进行斜距改正，同时对目标阴影区进行了处理；对文献[1]的灰度不均衡的改正算法进行了改进。利用小波变换检测出灰度突变区，根据剔除突变区后计算的灰度改正系数进行航向上的灰度改正，并用模拟数据和实际数据进行了验证；鉴于波束展宽效应对远场目标造成的拖尾效应，论述了对拖尾效应使用的去卷积的改正算法。  相似文献   

Magnitude calibration of north Indian earthquakes   总被引：13，自引：0，他引：13  

N. N. Ambraseys  J. Douglas 《Geophysical Journal International》2004,159(1):165-206

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