澜沧-耿马Ms7.6级地震前兆综合加权信息量的变化     

张昭栋  张华  冯志军 《大地测量与地球动力学》2000,20(4):71-77

在地震综合信息量的基础上,改进了地震前兆异常的出现概率的计算方法,得到地震前兆综合加权信息量.利用"地震预报专家系统"的思想对每一异常事件进行综合评估.考虑到异常的可靠性、有效性、显著性及相互关联性,给予不同的权重,以每一异常事件的最可能发震时间来估算异常出现的概率,计算了澜沧-耿马地震的地震前兆综合加权信息量,并对这种信息量变化的特点进行了分析.  相似文献   

青藏高原区域重磁异常的东西向分区及其构造地质特征   总被引：2，自引：1，他引：2       下载免费PDF全文

薛典军  姜枚 吴良士李庆庆汪兴旺 《中国地质》2006,33(4):912-919

自从大陆整合以来作为一个整体的青藏高原继续受着印度板块向北俯冲的影响,也必定不断地改造着原各地体的结构构造,形成了高原整体意义上东西向的差异。这种差异与原本各地体的组成、结构和东西向延伸不一致。这不仅表现在南北向断裂构造跨各单个地体范围的出现,而且,逐步形成了东西的分区。这种分区突出地表现在区域重力与磁场的特征上,这不仅是局部的岩石磁性与密度变化的结果,而且是由于印度板块向北俯冲过程中,在其前缘的不同部位上经受的压力不同,以及地块的隆升与扩张作用的差异造成了高原东西各区段的地壳组分与厚度的变化。青藏高原的南北向断裂构造并非地壳上层的局部断裂,它具有深层的原因。由于印度板块向北推进的过程中不是均匀地齐头并进,而是在帕米尔高原以东的青藏高原范围内存在着推进速度和俯冲深度的差异,随着高原隆升的加剧高原本身出现断裂,自中新生代以来就存在着一定差异,所以南北向的断裂构造比目前地表见到的多些,而且具有较大的深度,Moho面的深度和地壳厚度都受南北向断裂的控制,并形成了区域重磁场的变化。同时,高原的东西向拉张作用也使南北断裂带发育加剧。  相似文献   

RELATION BETWEEN SUMMER TYPHOON FREQUENCY ANOMALIES IN WEST PACIFIC AND ENSO EVENTS AND THE ANOMALOUS ATMOSPHERIC CIRCULATION CHARACTERISTICS     

周学鸣  魏应植  吴陈锋 《热带气象学报(英文版)》2006,12(1):16-23

By using data of serially numbered typhoons in northwestern Pacific and NOAA OLR data and NCEP/NCAR reanalysis data of wind field, based on the statistics and study of the relationship between the calendar years with more (or fewer) summer typhoons and ENSO events, we compared the composites of OLR eigenvectors and tropical summer wind fields during El Nino and La Nina events with more or fewer than normal summer typhoons, respectively. The results show that, in summer, without remarkable systematic anomalies of Mascarene High and Australia High in South Hemisphere, the anomaly of Walker circulation will dominate and follow the rule of ENSO impacts to atmospheric circulation and typhoon frequency. Otherwise, when systematic anomalies of Australia High appear during the El Nino events, circulation anomalies in the South Hemisphere will dominate, and many more typhoons will occur. In 1999, which is a special year of La Nina events, northward and eastward monsoon was induced by the stronger Mascarene High, and fewer typhoons arose. The typhoon source are regions where weak vertical wind shear, warm pool in western Pacific and the area with monsoon troughs are overlapping with each other. Finally, this paper analyzes and compares the source locations and ranges of more (fewer) typhoons in the events of El Nino and La Nina, respectively.  相似文献   

新源4.7级地震前地下流体前兆异常特征     

朱成英  高小其  地里下提·克优木  李新勇 《内陆地震》2006,20(2):149-154

2001年3月24日在新疆新源发生MS4.7地震,震前北天山地区的地下流体相继出现一些前兆异常,并且以中短期异常为主,异常主要集中在距震中约265 km的乌鲁木齐附近。通过观测事实,分析了本次地震前北天山地区地下流体前兆异常的特征。  相似文献   

2003年内蒙巴林左旗-阿鲁科尔沁旗5.9级地震及其前兆异常分析     

陈立强  张跃刚  胡新亮  袁国旭  李明威 《华北地震科学》2006,24(1):43-46

2003年8月16日内蒙古巴林左旗—阿鲁科尔沁旗之间发生了Ms5.9级地震,震前该区测震学指标和河北省北部距该地区较近台站的前兆测项中都出现了一些异常。本文对这些异常的特征进行了分析,同时讨论了这些异常和这次地震的关系。这次地震打破了华北、东北地区的5级地震平静,可能预示新一轮地震活跃的开始。  相似文献   

THE EAST ASIAN SUBTROPICAL SUMMER MONSOON INDEX AND ITS RELATION WITH THE CLIMATE ANOMALIES IN CHINA     

刘宣飞  汪靖 《热带气象学报(英文版)》2007,13(1):57-60

A new East Asian subtropical summer monsoon circulation index is defined, where the barotropic and baroclinic components of circulation are included. Results show that this index can well indicate the interannual variability of summer precipitation and temperature anomalies in China. A strong monsoon is characterized by more rainfall in the Yellow River basin and northern China, less rainfall in the Yangtze River basin, and more rainfall in south and southeast China, in association with higher temperature in most areas of China. Furthermore, comparison is made between the index proposed in this paper and other monsoon indexes in representing climate anomalies in China.  相似文献   

THE RELATIONSHIP BETWEEN SCS SUMMER MONSOON INTENSITY AND OCEANIC THERMODYNAMIC VARIABLES AT DIFFERENT TIME SCALE     

谷德军  纪忠萍  王东晓  梁建茵  方一川 《热带气象学报(英文版)》2007,13(1):85-88

The oscillation characteristics of 1948 - 2003 South China Sea (SCS) summer monsoon intensity (SCSSMI) is analyzed by wavelet transform and the relationship between SCSSMI filtered by Lanczos filter at different time scale and oceanic thermal conditions is studied. The results show that SCSSMI exhibits dominant interannual (about 4 a), decadal (about 9 a) and interdecadal (about 38 a) oscillation periods. The interannual variation is the strongest and the interdecadal variation the weakest. The region of significant correlation between SCS summer monsoon intensity and oceanic thermodynamic variables at different time scale is greatly different. Significant correlation area of interannual variation of SCSSMI is concentrated in near equatorial region. Corresponding correlation displays quasi-biannual variability. If positive anomalies of SST and the depth of thermocline happen in eastern equatorial Indian Ocean and western equatorial Pacific, and negative anomalies of SST and the depth of thermocline happen in western equatorial Indian Ocean and eastern equatorial Pacific in previous autumn and winter, the interannual variation of SCSSMI will enhance. If the condition is contrary, interannual variation of SCSSMI will weaken. The interannual variation of SCSSMI will influence SST. The region surrounding SCS and east of Australia shows significantly negative correlation in autumn, and significantly positive correlation exhibits in west equatorial Indian Ocean, eastern equatorial Pacific and equatorial Atlantic in winter. The decadal variation of SCSSMI is modulated by PDO. Interdecadal variation of SCSSMI is relevant to the global warming and PDO.  相似文献   

中国夏季降水异常分布的非线性特征   总被引：2，自引：2，他引：2  

居丽丽  郭品文  徐同 《气象与减灾研究》2007,30(2):13-17

运用基于前馈型人工神经网络的非线性主成分分析方法(NLPCA),对中国近50 a夏季降水异常分布的非线性特征进行了分析。结果表明,中国夏季降水的异常分布具有一定的非线性特征,当夏季降水距平的一维NLPCA近似在非线性主成分取极端相反位相时,对应的空间分布型表现出明显的不对称性;一维NLPCA对夏季原始降水距平场的近似,比传统一维PCA的近似更为逼真。  相似文献   

北祁连西段熬油沟及卡洼沟一带Au、Pt、Pd异常特征及找矿方向          下载免费PDF全文

刘养雄 《甘肃地质》2007,16(1):17-22

北祁连西段作为甘肃一个重要的多金属成矿带，随着地质找矿工作不断地加强，日渐重要。根据熬油沟及卡洼沟一带水系沉积物、岩屑和岩石剖面测量结果，对Au、Pt、Pd和Pb、Zn等成矿元素的分布特征和组合关系进行了分析，总结了该处成矿地质背景和地球化学异常特征，指出了找矿方向。  相似文献   

纳米级微粒地球化学测量中异常重现性研究     

刘应汉  赵传东  孔牧  张华  张勤  任天祥 《物探化探计算技术》2007,(Z1)

纳米级微粒测量是寻找隐伏矿的新方法,选取实地模拟实验和在已知隐伏矿区,利用液态捕集剂和等离子体质谱分析测试样品,进行重复测量试验,研究结果表明,不同成矿元素,在地表形成异常的运移富集速率不同,其运移速率主要取决于纳米级微粒本身的地球化学性质,地下上升气流、断裂等裂隙有利于微粒的上升运移富集;纳米级微粒地球化学重复测量时,异常可具有良好的重现性,但异常重现较常规气体缓慢,通常需要2~3个月。  相似文献