Geomagnetic diurnal-variation anomalies and their relation to strong earthquakes     

Ding Jian-hai  Liu Jie  Yu Su-rong  Xiao Wu-jun 《地震学报(英文版)》2004,17(1):85-93

The diurnal-variation anomalies of the vertical-component in geomagnetic field are mainly the changes of phase and amplitude before strong earthquakes. On the basis of data recorded by the network of geomagnetic observatories in China for many years, the anomalous features of appearance time of the minima of diurnal variations (i.e, low-point time) of the geomagnetic vertical components and the variation of their spatial distribution (i.e, phenomena of low-point displacement) have been studied before over 30 strong earthquakes with M _S≥6.6 such as Kunlunshan M _S=8.1 earthquake on November 14, 2001; Bachu-Jashi M _S=6.8 earthquake on February 24, 2003; Xiaojin M _S=6.6 earthquake on September 22, 1989, etc. There are good relations between such rare phenomena of geomagnetic anomalies and the occurrence of earthquakes. It has been found that most earthquakes occur in the vicinity of the boundary line of sudden change of the low-point displacement and generally within four days before and after the 27th or 41st day counting from the day of appearance of the anomaly. In addition, the anomalies of diurnal-variation amplitude near the epicentral area have been also studied before Kunlunshan M _S=8.1 earthquake and Bachu-Jiashi M _S=6.8 earthquake. Foundation item: National Science Technology Tackle Key Project during the Tenth Five-year Plan (2001BA601B01-05-04)  相似文献   

Realistic Modeling of Seismic Wave Ground Motion in Beijing City   总被引：5，自引：0，他引：5  

Z. Ding  F. Romanelli  Y. T. Chen  G. F. Panza 《Pure and Applied Geophysics》2004,161(5-6):1093-1106

— Algorithms for the calculation of synthetic seismograms in laterally heterogeneous anelastic media have been applied to model the ground motion in Beijing City. The synthetic signals are compared with the few available seismic recordings (1998, Zhangbei earthquake) and with the distribution of observed macroseismic intensity (1976, Tangshan earthquake). The synthetic three-component seismograms have been computed for the Xiji area and Beijing City. The numerical results show that the thick Tertiary and Quaternary sediments are responsible for the severe amplification of the seismic ground motion. Such a result is well correlated with the abnormally high macroseismic intensity zone in the Xiji area associated with the 1976 Tangshan earthquake as well as with the ground motion recorded in Beijing city in the wake of the 1998 Zhangbei earthquake.  相似文献   

长江三角洲地区近实时GPS气象网   总被引：7，自引：3，他引：7  

丁金才  叶其欣 《气象》2003,29(6):26-29

简述了GPS气象学的发展动态和长江三角洲地区GPS气象网的概况，着重介绍了如何解决计算方法和设备、通信系统、产品实时演示系统和系统准业务化管理等问题，实现GPS气象网的近实时运转。  相似文献   

中国地震台网、全球地震台网地震目录数据库和震相数据库     

王科英  邹立晔  梁建宏  任克新  邱海江  丁秋琴  刘敬光 《地震地磁观测与研究》2003,24(3):37-43

地震目录和震相数据在地震学研究中具有重要意义，本文介绍了中国地震台网、全球地震台网地震目录数据库和震相数据库的内容和查询使用方法。  相似文献   

青藏高原东西向伸展及其地质意义   总被引：30，自引：4，他引：30  

张进江  丁林 《地质科学》2003,38(2):179-189

东西和南北向伸展是青藏高原最显著的地质特征之一。南北向伸展形成的东西走向伸展构造,主要包括藏南拆离系(STDS),和沿喀喇昆仑—嘉黎断裂带(KJFZ)发育的正断层体系。东西向伸展形成数目众多的南北走向伸展构造,它们切割青藏高原几乎所有的东西走向构造单元,包括羌塘地块、KJFZ和STDS等,说明东西向伸展以整体形式发生并同时波及整个青藏高原,而不是由以KJFZ和STDS为边界的不同地块的不均匀挤出所致。南北走向伸展构造在地表呈之字形,为南北向挤压形成的追踪张断裂;剖面上表现为被后期高角度正断层叠加的拆离断层,拆离断层形成于中-晚中新世而高角度正断层形成于上新世及以后。导致拆离断层的东西向伸展可能是南北向挤压的变形分解,后期高角度正断层作用可能是高原隆升后的垮塌所致。东西向伸展是控制青藏高原新生代浅色花岗岩和盆地形成的主要因素。  相似文献   

模糊综合评价-聚类复合模型在地下水质评价与分区中的应用   总被引：7，自引：0，他引：7  

罗定贵  王学军  后立胜 《地理与地理信息科学》2003,19(6):77-79,88

模糊综合评价法的评价结果具有模糊性，简单依据最大隶属度原则确定评价结果存在不足，笔者提出了模糊综合评价与模糊聚类分析相结合进行地下水质评价与分区的复合模型，并以MATLAB为平台开发了模型计算的常用函数。尝试将模型应用于抚州市地下水环境质量评价与分区，取得良好结果。  相似文献   

人工地震横波地质勘察——查明复杂、疑难地质问题的新方法     

高翠玲宋德文  李振升 《中国煤田地质》2003,15(2):52-54

人工横波地震是工程物探的一种新技术，但由于理论上存在一些误区，在工程实践中给地质解释带来一定困难。正确理解和计算横波波速是解决这个问题的首要任务，利用多次叠加时动校正的速度能量团计算横波速度比较可靠，该技术的应用已成功地解决了一些疑难复杂地质问题。准确的横波波速计算可使横波勘探得到更好地推广和应用，为工程设计和建设提供可靠的地质资料。  相似文献   

对胡家峪南和沟铜矿床控矿作用的认识     

梁庭祥  郭建华 《矿产与地质》2002,16(1)

探讨了南和沟铜矿床原岩建造、地层岩性、变质作用、地质构造的控矿作用及其多阶段、多源、多成因和层控性特点  相似文献   

The Electrical Conductivity of Gabbro at High Temperature and High Pressure     

王多君  李和平  易丽  张卫刚  刘丛强  苏根利  丁东业 《中国地球化学学报》2002,21(3):252-257

The electric conductivity of gabbro has been measured at 1.0 - 2.0 GPa and 320-700℃, and the conduction mechanism has been analyzed in terms of the impedance spectra.Experimental results indicated that the electric conductivity depends on the frequency of alternative current. Impedance arcs representing the conduction mechanism of grain interiors are displayed in the complex impedance plane, and the mechanism is dominated at high pressure.These arcs occur over the range of 102 - k× 105 Hz (k is the positive integer from 1 to 9). On the basis of our results and previous work, it is concluded that gabbro cannot form any high conductivity layer (HCL) in the middle-lower crust.  相似文献   

胶东金矿形成期间地幔流体参与成矿过程的碳氧氢同位素证据   总被引：57，自引：21，他引：57  

毛景文  赫英  丁悌平 《矿床地质》2002,21(2):121-128

胶东地区发育有两种类型的金矿床，以玲珑，焦家，三山岛，乳山为代表的石英脉型-破碎蚀变岩型和以大庄子，蓬家夼为代表的胶莱盆地北缘滑脱破碎带内的角砾岩型金矿，本文选择了两种类型中的玲珑，三山岛和大庄子金矿床进行碳氧氢同位素测定。初步认为两类金矿属于同一成矿系统，它们形成于120Ma左右的华北克拉通岩石圈减薄和软流圈上涌期间，岩浆流体和地幔脱气与胶东世界级金矿的形成密切相关，在石英脉型-破碎蚀变岩型矿石中可见深刻的地幔流体和岩浆流体的“烙印”。形成于滑脱破碎带中的角砾岩金矿流体与中生代大气降水和海相碳酸盐岩发生了强烈的交换作用。  相似文献