Rising grain prices in response to phased climatic change during 1736–1850 in the North China Plain     

Wen  Yanjun  Fang  Xiuqi  Liu  Yang  Li  Yikai 《中国科学:地球科学(英文版)》2019,62(11):1832-1844

Grain price volatility during historical periods is regarded as an important indicator of the impact of climate change on economic system, as well as a key link to adjust food security and social stability. The present study used the wheat prices in Baoding Prefecture, China, during 1736–1850 to explore connections between climatic transition and grain price anomalies in the North China Plain. The main findings were as follows:(1) The grain price change showed an apparent correspondence with climatic transition. The period 1781–1820 was a transition phase, with more extremes and decreased precipitations when the climate shifted from a warm phase to a cold one. Corresponding with the climatic transition, the grain price during 1781–1820 was characterized by that the mean of the original grain price series was significantly higher(lower) than the previous(later)phase, and the variance and anomaly amplitude of the detrended grain price series was the highest during 1736–1850.(2) The correspondence between grain price extremes and drought events occurred in phases. Five grain price extremes occurred following drought events during 1781–1810, while extreme droughts were the direct cause of the grain price spike during 1811–1820.(3) Social stability affected by climate change also played an important role in the grain price spike between 1811 and 1820. Paralleling the pathway of "precipitation-grain production-grain price", climate change could have an impact on grain price via the pathway of "precipitation-grain production-grain price-famine-uprising-grain price", as shown during the Tianli Uprising in 1813. These findings could contribute to an improved understanding of the interaction between climate change and human society during the historical period.  相似文献   

Archaea,the tree of life,and cellular evolution in eukaryotes     

Jing XIAO  Lu FAN  Dingfeng WU  Yanbing XU  Dengxun LAI  William F.MARTIN  Ruixin ZHU  Chuanlun ZHANG 《中国科学:地球科学(英文版)》2019,(3):489-506

The early history of life harbours many unresolved evolutionary questions, none more important than the genomic origin and cellular evolution of eukaryotes. An issue central to eukaryote origin concerns the position of eukaryotes in the tree of life and the relationship of the host lineage that acquired the mitochondrion some two billion years ago to lineages of modern-day archaea. Recent analyses indicate that the host lineage branches within the Archaea, prompting the search for novel archaeal lineages that can improve our understanding of the cellular evolution of eukaryotes. Here we give a brief review of the studies on Archaea, the tree of life and the cellular evolution of eukaryotes, which is followed by an overview of recent progress fueled by new genomic technologies and recent status of archaeal research in China. Future directions for the study of early evolution are considered.  相似文献   

强震动记录H/V谱比法计算处理的若干关键环节     

姚鑫鑫  任叶飞  温瑞智  戴嘉伟 《震灾防御技术》2019,14(4):719-730

强震动记录H/V谱比法自提出以来,已广泛应用于地震工程各研究领域中。但对数据处理的2个关键环节——Taper预处理及傅氏谱平滑未有详细研究。因此,本文针对强震动记录H/V谱比法计算涉及的重要数据处理过程,对四川地区19个强震动台站在汶川地震余震中获取的642组强震动记录开展研究。研究实例表明:S波H/V谱比振幅在周期 < 1s时高于全时程,论证计算H/V谱比时截取S波窗口的必要性;S波窗口的截断会引起傅里叶振幅谱的边瓣效应,若不加以处理,将显著影响低频部分H/V谱比结果,Taper预处理对于消除这种截断误差具有良好效果;在兼顾平滑效果及卓越周期识别准确度的基础上,通过不同带宽的Parzen窗试算,认为0.5Hz带宽宜用于傅里叶H/V谱比曲线平滑。  相似文献   

考虑填充墙影响的钢筋混凝土厂房结构地震易损性分析     

梁志强  徐超  温增平 《震灾防御技术》2019,14(4):707-718

采用对角斜撑模拟纵向填充墙的作用,建立考虑填充墙和不考虑填充墙厂房结构模型,采用拉丁超立方抽样技术建立考虑材料不确定性的结构分析样本,基于随机Pushover分析确定结构不同破坏状态下的统计参数。综合考虑结构材料强度及输入地震动不确定性的影响,通过非线性时程分析开展单层钢筋混凝土厂房结构易损性研究,在此基础上比较结构横、纵向易损性的差异,研究填充墙对结构易损性的影响。研究结果表明:钢筋混凝土厂房结构体系横向地震易损性显著大于纵向地震易损性;对纵向结构体系而言,加入填充墙会明显降低结构易损性,但在相同强度的地震动作用下,填充墙破坏程度比主体结构严重,这与厂房结构的实际震害特征相符。  相似文献   

PALEO-EARTHQUAKE STUDY METHODS ON BEDROCK FAULT SURFACE—HISTORY,CURRENT SITUATION,SUGGESTIONS AND PROSPECTS          下载免费PDF全文

ZOU Jun-jie  HE Hong-lin  YOKOYAMA Yosuke  WEI Zhan-yu  SHI Feng  HAO Hai-jian  ZHUANG Qi-tian  SUN Wen  ZHOU Chao  SHIRAHAMA Yoshiki 《地震地质》2019,41(6):1539-1562

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新型雷电预警系统在地震台站的应用     

全建军  陈珊桦  赖见深  郑永通  陈美梅  林慧卿 《华北地震科学》2019,37(3):50-55

福建地区的雷电活动频繁,地震台站的数据完整性和数据质量因雷电灾害严重降低。为确保台站仪器稳定运行及数据有效可靠,福建局实施多个措施对地震台站内、外部防雷进行整体改造。新型雷电预警系统设定多级报警阀值,并实时监视台站20km范围内大气电场强度,当系统监测值超阀值时,则发出预警并自动切换电源,为前兆仪器设备的防雷发挥着至关重要作用,也为取代人工断电模式提供安全保证,有利于地震台站稳定运行。  相似文献   

基于FLAC3D数值模拟的清徐地裂缝与交城断裂成因关系研究     

曾金艳  李自红  陈文 《震灾防御技术》2020,15(1):114-122

基于断裂力学理论,应用FLAC3D数值模拟方法对交城断裂活动时附近土体的变形特征进行模拟计算。计算结果表明:断层活动带动上覆土层差异沉降及应力场变化,当断层错动量达到一定程度,断层附近出现拉应力区,土体在拉张应力和自身重力作用下产生垂直差异形变,从而产生地裂缝。将数值模拟结果与方山探槽揭示的地裂缝剖面特征进行对比,二者结果相互印证,说明清徐地裂缝是交城断裂活动的结果,二者具有明显的对应关系,地裂缝为构造成因裂缝。数值模拟结果为研究断裂和地裂缝成因关系提供了佐证。  相似文献   

2018年2月12日河北永清4.3级地震强震动记录分析     

郭秋娜  温超  周月玲  李姜 《震灾防御技术》2020,15(2):329-338

2018年2月12日河北省廊坊市永清县发生4.3级地震,震中位于廊固凹陷内的河西务断裂附近,国家强震动台网中心获取74组强震动记录,本文对触发台站进行场地分类,结果显示大部分为Ⅰ类场地(51.35%),其次为Ⅱ类场地(35.14%)和Ⅲ类场地(13.51%)。根据5个典型台站加速度时程记录及反应谱分析本次地震强震动特征,并对各台站峰值加速度反应谱与方位角和震中距的关系进行分析。采用克里格插值方法绘制地震仪器烈度分布图,由于台站分布不均,导致极震区附近烈度影响场计算缺值现象,本文通过拟合本次地震强震动记录得到该地区地震动衰减关系,在空白区域建立空间随机假设台站进行补点插值,解决了计算缺值问题,为缺少台站记录的震区提供准确快速制作烈度分布图的思路,为震害调查和地震应急救援提供重要依据。  相似文献   

Effective elastic thickness of the lithosphere from joint inversion in western China and its implications*          下载免费PDF全文

Wen Shi  Shi Chen  Jiancheng Han 《地震科学（英文版）》2020,33(1):1-10

The western China lies in the convergence zone between Eurasian and Indian plates. It is an ideal place to study the lithosphere dynamics and tectonic evolutions on the continental Earth. The lithospheric strength is a key factor in controlling the lithosphere dynamics and deformations. The effective elastic thickness (T_e) of the lithosphere can be used to address the lithospheric strength. Previous researchers only used one of the admittance or coherence methods to investigate the T_e in the western China. Moreover, most of them ignored the internal loads of the lithosphere during the T_e calculation, which can produce large biases in the T_e estimations. To provide more reliable T_e estimations, we used a new joint inversion method that integrated both admittance and coherence techniques to compute the T_e in this study, with the WGM2012 gravity data, the ETOPO1 topographic data, and the Moho depths from the CRUST1.0 model. The internal loads are considered and investigated using the load ratio (F). Our results show that the joint inversion method can yield reliable T_e and F values. Based on the analysis of T_e and F distributions, we suggest (1) the northern Tibetan Plateau could be the front edge of the plate collision of Eurasian and Indian plates; (2) the southern and part of central Tibetan Plateau have a strong lithospheric mantle related to the rigid underthrusting Indian plate; (3) the southeastern Tibetan Plateau may be experiencing the delamination of lithosphere and upwelling of asthenosphere.  相似文献   

Stratosphere amplifies the global climate effect of wildfires     

Wei  Ke  Chen  Wen  Xu  Luyang  Zhou  Chunjiang 《中国科学:地球科学(英文版)》2020,63(2):309-311

The summer of 2019 witnessed a great number of wildfires around the globe.For example,wildfires scorched huge swaths of Alaska,British Columbia in Canada,and parts of Greenland.And forest fires in Siberia and the Far East of Russia were also very serious,affecting nearly 3 million hectares of land,and putting some parts of Russia into a state of emergency.In particular,forest fires in the Amazon region had attracted global attention.According to Science,as of August 24,BraziPs National Institute for Space Research had counted more than 41000 fires this year,86%more than last year,compared with 22000 in the same period last year.Scientists in Brazil and elsewhere believe that the recent increase of wildfires is closely related to the increasing ac・tivities of deforestation(Arruda et al.,2019;Escobar,2019).  相似文献