永登5.8级地震前后剪切波分裂特征          下载免费PDF全文

张范民  李清河  荣代潞 《地震工程学报》1998,20(3):9-15

应用１９９０年至１９９５年ＣＤＳＮ台网兰州数字台的记录和中法合作建立的朗索数字台的记录,研究了１９９５年７月２２日甘肃永登５．８级地震前后剪切波分裂的特征,利用最大特征值法,波形识别算子法和最大似然法定量确定了剪切波分裂的快慢波时间延迟及快波偏振方向,结果表明,在永登地震前大约１年的时间内剪切波分裂延迟增大,快剪切波偏振方向也从ＮＥ向转为ＮＷ向,地震后剪切除波分裂时间延迟和偏振方向很快恢复,其时间  相似文献   

含裂隙双相各向异性介质中的地震波传播   总被引：5，自引：0，他引：5  

冯德益  聂永安 《地震工程学报》1998,20(1):1-8

基于各向异性介质和含裂隙双相介质中的地震波传播理论,导出了具有四阶对称轴的含裂隙双相各向异性介质的本构关系与波传播的运动方程．指出在含裂隙双相各向异性介质中可能传播６种类型的准纵横波,即快纵波ＱＰ１,慢纵波ＱＰ２,两个分裂的快横波ＱＳＶ１,ＱＳＨ１和两个分裂的慢横波ＱＳＶ２,ＱＳＨ２．并以平面波传播为例作了进一步分析  相似文献   

The Effect of Atmospheric Organic Compounds on the Fe-Catalyzed S(IV) Autoxidation in Aqueous Solution     

Irena Grgić  Andreja Dovžan  Gorazd Berčič  Vida Hudnik 《Journal of Atmospheric Chemistry》1998,29(3):315-337

Laboratory experiments were conducted with real atmospheric aerosol particles as well as with synthetic solutions under dark conditions, to simulate some of the chemical features of aerosols. In solutions obtained by the leaching of aerosols (size range >D _ae: 0.4–1.6 m) that contained sufficient amounts of transition metal ions (e.g. Fe) and organic species (e.g. oxalate), S(IV) oxidation rates were significantly lower than those expected from the Fe-catalyzed S(IV) autoxidation in Milli-Q water. The results suggest that oxalate is responsible for much of the observed inhibition. Acetate and formate also inhibit the reaction, but to a much lesser extent. Oxalate has a strong inhibiting effect on the Fe-catalyzed S(IV) autoxidation at all investigated pH values (2.8, 3.7 and 4.5). It was established that Fe(III)-oxalato complexes affect the redox cycling of Fe(II)/Fe(III) and that the observed decrease of the reaction rate is caused by the reduced amount of catalytically active Fe(III) due to the complexation with oxalate. For the system Fe-S(IV)-O₂-oxalate at initial pH 3.7 the reaction rate was calculated using exponential simplification to account for oxalate influence on the amount of free Fe(III) by the following equation:–r_S(IV) = k · [S(IV)] · [Fe(III))] · e ^-b·[Ox]  相似文献   

S^2MP结构分析   总被引：1，自引：0，他引：1  

陈杰伦  朱江 《南京气象学院学报》1998,21(1):138-144

Ｓ＾２ＭＰ是ＳＧＩ刚刚推出的新一代体系结构,既具有ＭＰＰ的可扩展性,又具有ＳＭＰ的可编程性。将两者的优势集于一身。将Ｓ＾２ＭＰ与历史上曾经出现的两种多机结构进行比较,指出了Ｓ＾２ＭＰ结构的特点,分析结果认为Ｓ＾２ＭＰ是当代ＭＩＮＭＤ机器最具代表性的结构。  相似文献   

地理信息系统(GIS)在农业上的应用现状概述   总被引：27，自引：3，他引：27  

饶卫民  章家恩  肖红生  胡月明 《云南地理环境研究》2004,16(2):13-17

在概述地理信息系统(GIS)的概念、功能、应用领域的基础上，对GIS在农业资源管理与动态监测、作物估产、土地适宜性评价、病虫害预测预报与风险评价、精确农业等方面的应用现状进行了综述，并对GIS在农业中的应用前景以及新动态进行了探讨和分析，讨论了地理信息系统在农业上应用研究的重要性。  相似文献   

Record-High Losses for Weather Disasters in the United States During the 1990s: How Excessive and Why?     

Changnon  Stanley A.  Changnon  David 《Natural Hazards》1998,18(3):287-300

During 1990–1996 the United States experienced record-setting insured property losses due to numerous weather catastrophes, each event causing $100 million or more in losses (1991 dollars). The total loss in this 7-year period, after adjustment to inflation and other factors, was $39.65 billion with $15 billion coming from one event, Hurricane Andrew. In the 1990s, 72 catastrophes occurred, half of the total number in the 40 preceding years, 1950–1989. Although the total loss and the number of catastrophes were exceptionally high in the 1990s, the average loss per event was $551 million, only slightly more than the $467 million average for catastrophes during 1950–1989. Furthermore, storm intensities in the 1990s were slightly less than those during the preceding 40 years, revealing the excess losses of the 1990s to be a result of an extremely large number of damaging storms causing losses exceeding $100 million. Examination of historical values of most weather extremes including hurricanes, floods, and tornadoes, did not show an increase during the 1990s, revealing that weather changes were not the principal cause of more catastrophes. Examination of recent demographic shifts in the U.S. reveals two changes, each based on major re-locations to higher-valued property concentrated in areas either with a high frequency of damaging storms (Gulf and East Coast), or to where even a small but intense storm can cause huge losses (urban areas and West Coast). These shifts, plus the continuing growth of population in other storm-prone areas have greatly increased society's vulnerability to storm damage. An in-depth analysis of many conditions was required to establish that the high losses and numerous catastrophes of the 1990s were largely the result of societal changes and not major weather changes. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

Brine transport in porous media: On the use of Von Mises and similarity transformations     

C.J. van Duijn  R.J. Schotting 《Computational Geosciences》1998,2(2):125-149

In this paper we use a Von Mises transformation to study brine transport in porous media. The model involves mass balance equations for fluid and salt, Darcy's law and an equation of state, relating the salt mass fraction to the fluid density. Application of the Von Mises transformation recasts the model equations into a single nonlinear diffusion equation. A further reduction is possible if the problem admits similarity. This yields a formulation in terms of a boundary value problem for an ordinary differential equation which can be treated by semi‐analytical means. Three specific similarity problems are considered in detail: (i) one‐dimensional, stable displacement of fresh water and brine in a porous column, (ii) flow of fresh water along the surface of a salt rock, (iii) mixing of parallel layers of brine and fresh water. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Shear-wave velocity in marine sediments on young oceanic crust: constraints from dispersion analysis of Scholte waves     

H. Heinz- Essen  Ingo Grevemeyer  Rolf Herber  & Wilfried Weigel 《Geophysical Journal International》1998,132(1):227-234

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Geochemistry of Jinman Copper Vein Deposit West Yunnan province,China—Ⅱ.Fluid Inclusion and Stable Isotope Geochemical Characteristics   总被引：1，自引：0，他引：1  

Ji Hongbing  Li Chaoyang 《中国地球化学学报》1998,17(1):81-90

The Jinman deposit is a Ag-bearing copper vein deposit located at the north margin of the Lanping-Simao back-arc basin in West Yunnan. Systematic studies of fluid inclusions and stable isotopes are presented in this paper. The filling-replacement stage and the boiling-exhalative precipitation stage of mineralization took place atT ₁ = 140–280°3 andT ₂ = 94–204°C under pressure of (600 – 1200) x 10⁵ Pa. The salinity of ore-forming solutions ranges from 5 wt% –20.8 wt% (NaCl). Sulphide δ³⁴S(CDT) values are in the range of -9.6%.– +11.03%. with a range of 22. 66%. showing an apparent “pagoda”-shaped distribution in histogram. Meanwhile, the δ³⁴S values of the various sulphides are consistent with the characters of isotope equilibrium fractionation, i.e., δ³⁴ S_Py>δ³⁴S_Cp>δ³⁴S_Bn. The TS/TOC ratios of the ores are widely variable between 0.16 and 5.54 with no correlation of any kind can be established. According to the model of Ohmoto, the oxidation-reduction ratios of sulfur species in ore-forming solutions at the two mineralization stages were calculated to be R′₁ = 2.16 x 10^-17 and R′₂ = 1.55 x 10⁴. δ¹³Coo₂(PDB) values obtained from fluid inclusions in calcite and quartz are between -8.12%.-3.18%., averaging -5.26%., which are comparable with the isotopic composition of mantle-derived CO₂. Inclusions in quartz yield δ¹³CCH₄ (PEB) between -32. 11%. and -22.04%. (averaging -26.69%.), similar to that of methane in modern geothermal gases. For the ore-forming solutions, δ¹⁸ OH₂O (SMOW) values are between -10.57%. and +9.77%. and δDH₂O (SMOW) are between -51%. and -135%. Considering the effect of isotope exchange during water-rock reactions, most of the data are plotted along or close to the line defined by the reaction of meteoric water with clastic rocks, while a small part of the points fall near the reaction line of magmatic water with clastic rocks. In δ¹³C vs. δ18O diagram, the ore-forming solutions are plotted for the most part into the mixing area between the meteoric fluid and the deep-seated fluid and partially on the mixing line of P = 1. This project was founded by the “Eighth Five-Year Plan Period” State Key Program (85–901) and the Open Lab. of Ore Deposit Geochemistry, Chinese Academy of Sciences.  相似文献   

辽东半岛南部金伯利岩成因讨论     

郑建平  路凤香  叶德隆 《国土资源》1989,(4)

辽东半岛南部金伯利岩产于辽东台隆复县—新金坳陷内的基底隆起区。金伯利岩浆的形成是多种地质作用的综合结果。控制岩浆形成的主体作用是具亏损和富集双重特征地幔的部分熔融,贫金刚石金伯利岩体曾经历了强烈的分离结晶作用和地幔易熔组分的萃取作用。深部富含不相容元素的C—H—O流体加入上覆亏损地幔中,引起地幔底辟体上升,在大约215km深度处地温线与橄榄岩C—H—O固相线交切,引起橄榄岩1%—3%的熔融,形成粘度为0.0211Pa·s,密度为2.76g·cm~(-3)、氧逸度为2.92×1.01325×10~(-6)Pa的金伯利岩浆,这种岩浆沿着宽2.7m的裂隙,以约18m/s的速度上升、就位成岩。  相似文献