文献记录的河西地区小冰期旱涝变化及其机制探讨     

董惟妙  安成邦  赵永涛  李虎 《干旱区地理》2012,35(6):946-951

基于文献资料重建了河西地区AD 1436-1949旱涝灾害等级序列,结果表明所研究的500余年内河西地区大体出现三次明显的干旱时段,分别为AD 1460-1539、AD 1616-1665和AD 1907-1949,而AD 1725-1748以及AD 1879-1906则为相对湿润时期。重建的旱涝等级序列与毗邻祁连树轮记录的干湿变化存在高度一致的对应关系;将其与NAO指数对比发现,冷期NAO高指数年对应旱灾多发,NAO低指数年对应涝灾多发。  相似文献   

提高大震速报工作质量的几项建议     

孟彩菊  邱桂兰  赵春华  靳玉贞  黄春玲 《山西地震》2012,(1):17-23,45

结合2009年1月1日起正式执行的《国家速报台站大地震速报评比标准》的要求,对太原基准地震台2009年速报工作中存在的主要问题进行了总结分析,对如何改进工作,有效提高速报质量,提出了改进措施。  相似文献   

江西地区有感地震史记     

邓辉  卢福水  陈家兴  毛华 《地震地磁观测与研究》2012,33(3):337-341

通过搜集江西省各地方史志地震记载,在前人研究基础上,给出江西省历史有感地震的筛选原则和确定方法,整理分析相应有感地震,并在中国有感地震目录中提取江西有感地震,删减重复部分,增补遗漏的史志有记载的有感地震,从而编辑江西地区相对完整的历史有感地震目录。  相似文献   

唐山丰南M4.1级地震强震记录分析   总被引：3，自引：2，他引：1  

冉志杰  杨歧焱  周月玲  孙丽娜  吕国军  孟立朋  范强  彭远黔 《震灾防御技术》2012,7(4):367-376

2010年4月9日唐山丰南发生M4.1级地震,津冀地区共有36个强震台站获取到强震记录,记录的最大加速度为58.92cm/s2,通过对比强震记录的峰值,发现该地震竖向峰值比水平向大,在三个分量上加速度傅氏谱谱型以多峰为主。通过对强震记录频谱特征进行分析,得出随着震中距的增大,反应谱高频成分衰减快于低频成分,竖向与水平向加速度比值与常规认为的1/2—2/3差别较大。通过对本次强震动记录反应谱标定并结合唐山地区3.5级以上地震记录,获得唐山地区土层场地反应谱谱型参数。  相似文献   

35000 aBP以来四川洪雅的孢粉记录与气候变化   总被引：1，自引：0，他引：1  

石胜强  袁道先  罗伦德  赵增友  郝秀东 《中国岩溶》2012,31(2):121-130

运用古气候参数方法对四川洪雅GMH剖面进行孢粉分析,结合定年数据,分析出本区自晚更新世晚期以来的植被变化和气候变化并与我国南方石笋记录等进行对比分析。研究表明:从大约35670 aBP以来,四川洪雅地区总体经历了暖湿—温润—凉干—温润—冷干—温湿—凉润—暖湿—温润的气候变化过程,其间多有反复;GMH剖面孢粉记录与我国南方石笋记录在古气候变化的大趋势上基本一致,对H3、H2、H1、YD等气候事件反映明显;E带(21100-17000 aBP)对应的降温减湿期较石笋记录提前出现与研究区位于第一、二级阶梯过渡地带、山前台地的地貌特征有关;对比发现I带中的温干气候期(约2150aBP前后)具有一定的区域性意义。   相似文献   

塔里木河下游政区与交通变化所反映的历史环境变迁   总被引：3，自引：1，他引：2  

韩春鲜  谢雪梅 《中国沙漠》2010,30(3):477-482

利用历史文献和考古成果,结合野外调研,研究历史时期以来塔里木河下游的行政变化和交通变迁,在此基础上分析了下游生态环境的演变特征。研究认为,从细石器到汉晋时期,塔里木河下游气候湿润,生态环境比较稳定,人类活动从原始经济向城邦文明稳步演进,对外交通便利,形成塔里木盆地东部重要的鄯善（楼兰）独立王国;东晋以后,气候逐渐变干,下游对外联系的主要交通枢纽和交通线路废弃,鄯善国消亡,塔里木河下游绿洲成为封闭的游牧区;18世纪中期以后气候湿润,下游绿洲归属于吐鲁番政区管辖,对外联系比较方便;19世纪末期,气候变化剧烈,趋向干旱,塔里木河下游与吐鲁番之间的政区、交通联系中断,开始属于塔里木河流域的上一级行政区管辖。  相似文献   

近代城市医院的空间布局及演化——以广州市为例   总被引：2，自引：0，他引：2  

刘桂奇 《热带地理》2010,30(3)

以广州市为例,引用广州志书资料和民国文献档案资料,采用历史文献、统计和空间分析方法,通过复原广州医院历史分布图,发现广州近代医院在景观扩散模式上,早期阶段属于墨渍式迁移扩散,之后,转向以区位条件优次为主要选址依据的等级扩散;在选址布局上,形成以老城高优势度区域为中心,自中心向外围环状递减的等级区域分布格局,而公立医院和私立医院密集于城市中心,教会医院和慈善医院散布在城市外围,在类型上,呈现为外围型和中心型相结合的空间形态。研究显示,广州近代医院的空间布局,主要受人口、经济和交通因素的影响,同时,政治、宗教、城区环境和医院特殊性等外部条件起着一定的制约或促进作用。  相似文献   

Analysis of historical landslide time series in the Emilia‐Romagna region,northern Italy     

Mauro Rossi  Annette Witt  Fausto Guzzetti  Bruce D. Malamud  Silvia Peruccacci 《地球表面变化过程与地形》2010,35(10):1123-1137

A catalogue of historical landslides, 1951–2002, for three provinces in the Emilia‐Romagna region of northern Italy is presented and its statistical properties studied. The catalogue consists of 2255 reported landslides and is based on historical archives and chronicles. We use two measures for the intensity of landsliding over time: (i) the number of reported landslides in a day (D_L) and (ii) the number of reported landslides in an event (S_event), where an event is one or more consecutive days with landsliding. From 1951–2002 in our study area there were 1057 days with 1 ≤ D_L ≤?45 landslides per day, and 596 events with 1 ≤ S_event ≤ 129 landslides per event. In the first set of analyses, we find that the probability density of landslide intensities in the time series are power‐law distributed over at least two‐orders of magnitude, with exponent of about ?2·0. Although our data is a proxy for landsliding built from newspaper reports, it is the first tentative evidence that the frequency‐size of triggered landslide events over time (not just the landslides in a given triggered event), like earthquakes, scale as a power‐law or other heavy‐tailed distributions. If confirmed, this could have important implications for risk assessment and erosion modelling in a given area. In our second set of analyses, we find that for short antecedent rainfall periods, the minimum amount of rainfall necessary to trigger landslides varies considerably with the intensity of the landsliding (D_L and S_event); whereas for long antecedent periods the magnitude is largely independent of the cumulative amount of rainfall, and the largest values of landslide intensity are always preceded by abundant rainfall. Further, the analysis of the rainfall trend suggests that the trigger of landslides in the study area is related to seasonal rainfall. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Sedimentary evidence of Late Holocene human activity in the Pearl River delta,China     

Y. Zong  F. Yu  G. Huang  J. M. Lloyd  W. W.‐S. Yim 《地球表面变化过程与地形》2010,35(9):1095-1102

This study examines the sedimentary evidence of human activities during the last 4000 years in the Pearl River deltaic area. The analyses are focused on indentifying agricultural signatures present in the sedimentary record and establishing the timing of a change from a simple, rice‐based agriculture to a more advanced, diverse agriculture. The examination is based on modern sediment and plant samples and a sediment core collected from the deltaic area. The analyses include particle size and diatom analysis to determine the environmental conditions that were associated with the period of human activities. Organic carbon isotope ratios and major metal elements reveal an expansion in commercial crop production and metal smelting in the Pearl River delta area about 2000 years ago. The input of organic matter from introduced sugarcane, a C4 plant, elevates the bulk organic carbon isotope values in the estuarine sediments above that represented by other common agricultural crops in the study area, including rice, banana and lotus, which are all C3 plants. The increase in bulk organic isotopic value coincides with the rise in the concentration of copper, iron and lead in the sedimentary sequence, suggesting a wider use of metal tools. These results indicate that advanced agriculture started about 2000 years ago as an expansion in human population took place in the area. This record also provides sedimentary evidence that help ascertain the timing and type of human activities that are linked to subsequent land reclamation on the deltaic plain, resulting in rapid shoreline advancement in the last 2000 years. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

公元1831年安徽凤台地震宏观震中考察   总被引：1，自引：0，他引：1       下载免费PDF全文

陈安国  刘东旺  沈小七  邵磊  王健 《地震学报》2010,32(4):495-503

公元1831年(清道光十一年)安徽凤台曾发生一次破坏性地震,史料记载情况基本一致,但现有各版地震目录所确定的震中位置存在分歧,震中位置竟多达4处.在分析已有资料的基础上,作者对该地震进行了实地考察.经综合分析认为,应当对此次地震的宏观震中进行调整,震中位置应改为32.88°N、116.89°E,名称相应变更为"安徽怀远西南地震".同时认为此次地震原来所确定的震级(614)偏大.  相似文献