Rainfall and Obtaining Information Regarding Earthquake Development Processes from Groundwater Level

Many factors can cause changes of groundwater level, such as the development process of an earthquake, rainfall, solid earth tides etc. Among these we are interested in information regarding earthquake development processes. Eliminating the influence of various disturbance factors is an effective way to obtain seismic development process information contained in the groundwater level. This paper provides two different ways to remove the rainfall effect, and compares the two methods by means of correlation analysis. Furthermore, based on these a logistic regression model is established to describe the seismicity level.     

Temporal vP/vS variation characteristics in different zones of China’s Capital Circle area before and after Wen’an earthquake

On July 4, 2006, an earthquake of MS5.1 took place in Wen’an, Hebei Province, just at the south center of China’s Capital Circle area digital seismograph network. It is the strongest event recorded ever since the network went into operation in 2002. We processed the vast amounts of phase data yielded by the 107 digital seismic stations between 2002~2007 using Wadati method. In order to improve the precision and stability of shear and compressional wave velocities (vP/vS) calculation, we impose a number of restrictions on the computation environment and condition, e.g., the earthquakes are densely concentrated, selected stations are limited in range, the number of stations in- volved in the computation is larger than 5 and linear fitting features high precision and small error. Under these restrictions, the study shows that vP/vS in and around Wen’an and Tangshan underwent a normal-low-normal proc- ess one year before Wen’an earthquake, vP/vS became obviously low and the low ratio lasted for about one year, meanwhile, little variation of vP/vS was seen in Xingtai, northwest of Beijing, southwest of Beijing, Beijing-Tianjin and Beijing; after the quake, the vP/vS returned normal in Wen’an and Tangshan. Error and stability analysis of the calculated result for vP/vS shows it is convincible that anomaly appeared in and around Wen’an and Tangshan be- fore Wen’an earthquake.     

内蒙古中西部地区视应力的时间和空间分布研究

依据Wyss和Brune(1968),Wyss(1979)地震视应力定义及Aki(1969)地震矩理论,根据内蒙古中西部构造及台站分布特点,将其分成中部(108°～114.8°E,38.5°～43°N),西部(106.2°～108.3°E,39.2°～41.2°N)两区域进行视应力时间和空间分布研究.     

利辛ML4．6地震与蒙城地电阻率变化特征

以消除年变化等短周期变化后的数据做为当月正常值,利用实测的月均值与正常值之比即月干扰比率、偏差等指标,突出反映月观测值在当月受到综合干扰因素影响的大小。从而突出地震前短临地电阻率异常。     

辽宁海城-岫岩地区尾波Q值研究

本文利用Sato单次散射模型,研究1999年至2007年辽宁海城-岫岩地区尾波Q值随时间的变化情况及1999年岫岩5.4级地震和2000年5.1级两次中强地震发生阶段该地区的尾波Q值变化。计算结果表明:该区在地震活跃阶段,Qc值随时间变化起伏较大,平均值相对较高,在岫岩5.4级主震前有短时升高现象,之后Qc值并没有明显的降低,直到强余震序列结束之后Qc值逐步降低,趋于平稳,通过对比该区在地震活跃阶段与平静阶段的Qc值变化,可以为未来该区的强震预测提供参考依据。     

Asymmetric variability between maximum and minimum temperatures in Northeastern Tibetan Plateau: Evidence from tree rings

Ecological systems in the headwaters of the Yellow River, characterized by hash natural environmental conditions, are very vulnerable to climatic change. In the most recent decades, this area greatly attracted the public's attention for its more and more deteriorating environmental conditions. Based on tree-ring samples from the Xiqing Mountain and A'nyêmagên Mountains at the headwaters of the Yellow River in the Northeastern Tibetan Plateau, we reconstructed the minimum temperatures in the winter half year over the last 425 years and the maximum temperatures in the summer half year over the past 700 years in this region. The variation of minimum temperature in the winter half year during the time span of 1578―1940 was a relatively stable trend, which was followed by an abrupt warming trend since 1941. However, there is no significant warming trend for the maximum temperature in the summer half year over the 20th century. The asymmetric variation patterns between the minimum and maximum temperatures were observed in this study over the past 425 years. During the past 425 years, there are similar variation patterns between the minimum and maximum temperatures; however, the minimum temperatures vary about 25 years earlier compared to the maximum temperatures. If such a trend of variation patterns between the minimum and maximum temperatures over the past 425 years continues in the future 30 years, the maximum temperature in this region will increase significantly.     

Late Eocene pollen records and palaeoenvironmental changes in northern Tibetan Plateau

The Eocene palaeovegetation landscape and palaeoclimate reconstructed from the pollen records in the Jiuquan Basin, northwest China provide some important information on the early uplift of the Tibetan Plateau and the origin and evolution of the aridification in northwest China. The records show the arid-semiarid scrubs with open forest palynofloras controlled by the subtropical high existed in northwest China during the 40.2–33.4 Ma. Four pollen assemblages are found: Nitrariadites-Cheno-podipollis-Pinaceae assemblage (40.2–37.9 Ma) is followed by Chenopodipollis-Nitrariadites assemblage (37.9–34.6 Ma), Pinuspollenites & Abietineaepollenites-Chenopodipollis assemblage (34.6–33.9 Ma), and Chenopodipollis-Nitrariadites assemblage (33.9–33.4 Ma). The percentage of thermophilic types is in anti-correlation with that of the dry types, which means the palaeoclimate is relatively warm-wet or cold-dry during most of that time. Such aridity may be related to the water vapor reduction and the planetary wind system movement northward in response to the cooling caused by small-ephemeral ice-sheets. Supported by the National Key Program for Developing Basic Sciences (Grant No. 2005CB422001), the National Science Foundation of China (Grant Nos. 40334038, 40421101) and the President Fund of Chinese Academy of Sciences     

筒仓与地基相互作用对支承柱端弯矩的影响

对钢筋混凝土柱承式筒仓动力时程分析表明,场地类别对支承柱端弯矩的变化有重要影响,在软弱场地上柱顶弯矩绝对值大于柱底弯矩绝对值;整体性较好的基础可以明显改善支承柱的受力,支承柱合理增设赘余杆也可以改善柱顶受力;文中提出了柱端弯矩增大系数及取值,以考虑地基与结构的相互作用.     

旅游地地方感的游客认知研究

体现旅游地地方特征的元素是各种类型旅游体验设计的源泉,引导不同文化背景的游客进行体验认知.形成游客的综合体验感.地方感包含了地方的客观特征和人们的主观认知两方面,而旅游地地方感的认知由地方认同和地方依赖两方面构成:其中地方认同主要来源于游客对地方独特性的感官、情感,以及对地方原真性的思考体验:地方依赖则主要来源于游客对地方依赖性的功能要素的体验.本文归纳旅游地地方感的构成要素,构建了由3大部分、11个因子构成的游客地方感认知测量的指标体系,通过问卷调查对游客的地方感认知进行定量调查.基于调查数据统计得到所有因子的评价得分,采用皮尔森相关分析的方法分析所有凶子之间的相关关系,归纳得到游客地方感认知的规律,以便为旅游地开发、规划、管理提供参考.