Interpretation of S-wave data from Tai’an-Xinzhou DSS profile and its relationship with Xingtai earthquakes

On the basis of S wave information from Tai’an-Xinzhou DSS profile and with reference to the results from P-wave interpretation, the 2-D structures, including S-wave velocity V _s, ratio γ between V _p and V _s; and Poisson’ s ratio σ, are calculated; the structural configuration of the profile is presented and the relevant inferences are drawn from the above results. Upwarping mantle districts (V _s≈4.30 km/s) and sloping mantle districts (V _s≈4.50 km/s) of the profile with velocity difference about −4% at the top of upper mantle are divided according to the differences of V _s, γ and σ in different media and structures, also with reference to the information of their neighbouring regions; the existence of Niujiaqiao-Dongwang high-angle ultra-crustal fault zone is reaffirmed; the properties of low and high velocity blocks (zones) including the crust-mantle transitionalzone and the boudary indicators of North China rift valley are discussed. A comprehensive study is conducted on the relation of the interpretation results with earthquakes. It is concluded that the mantle upwarps, thermal material upwells through the high-angle fault, the primary hypocenter was located at the crust-mantle juncture 30.0∼33.0 km deep, and additional stress excited the M _S=6.8 and M _S=7.2 earthquakes at specific locations around 9.0 km below Niujiaqiao-Dongwang, the earthquakes took place around the high-angle ultra-crustal fault and centered in the brittle media and rock strata with low γ and low σ values. This subject is part of the 85-907-02 key project during the “8th Five-Year Plan” from the State Science and Technology Commission.     

吉林-日本区深震特征及板块俯冲图像分析

根据USCS地震资料：分析了吉林-日本深震区地震的深度特征．结果表明：吉林-日本深震区地震位于太平洋板块与欧亚大陆板块的交界带上．其北支地震活动强于南支．同时也揭示了该区地震深度、地震频次以及地震能量之间的关系．指出其最容易发生强震的地震层位在570-580km左右。由深度资料推断板块间的作用方式，太平洋板块向欧亚大陆的挤压是一个由浅入深的过程，在不同的部位其俯冲角度与俯冲距离是不一样的，一般来说，倾角越大，俯冲越陡．水平延伸距离越短；反之，倾角越小．俯冲越平缓，水平延伸距离越长。     

冲绳海槽地区地壳结构与岩石层性质研究

用冲绳海槽地区地质、地球物理、地球化学数据与资料，对横跨大陆边缘—大洋板块的中国东部—冲绳海槽—琉球岛弧地区进行综合研究. 根据地震体波、面波成像结果，空间与布格重力异常及磁力异常的综合解释等结果，利用调和系数法对该研究区的地壳厚度进行了计算，并对地壳属性进行分析. 同时，选择中国东部东北地区的宽甸、华北地区的汉诺坝、华南的闵溪和台湾海峡的澎湖列岛与冲绳海槽和日本岛弧的新生代玄武岩开展元素—同位素对比研究. 结果认为冲绳海槽岩石层明显减薄，上地幔低速层已达到莫霍面，在地幔中已形成交代软流层. 元素—同位素研究表明：它不同于中国东部，与琉球岛弧地区的特点也不相同. 综合分析认为：冲绳海槽地壳属于过渡型地壳，与大洋地壳的许多特点颇为相似.     

基坑开挖与土钉支护的数值模拟

运用FLAC程序对深基坑土钉墙支护设计进行了数值模拟,分析了边壁土体的变形大小和土钉应力分布,并与现场实测结果对比,得出基坑顶的水平位移值与实测值相差不大,并对差值进行了分析。在应力方面,改善了土体内应力集中的现象,从而制约了土体的变形。剪应力在支护结构和坡角处有集中现象,在坡角处较为严重。     

Average recurrence intervals of strong earthquakes and potential risky segments along the Taiyuan-Linfen portion of the Shanxi graben system

Introduction In AD 1303, the great Hongtong, Shanxi, earthquake of magnitude 8 caused a very serious disaster, which killed over one hundred thousands people at least (Department of Earthquake Dis- *aster Prevention, State Seismological Bureau, 1995). On the occasion of commemorating this ca-tastrophe having occurred for 700 years, we have important problems that need to be answered: How long the average recurrence interval of the grea…     

Carbon isotopic studies of individual lipids in organisms from the Nansha sea area, China

Sediments contain abundant lipid compounds in general, which are used as biomarker compounds to study organic matter sources and reconstruct the pa-laeoenvironments[1—7]. However, lipid compounds in sediments are generally a mixture of various genetic components so that it is difficult to correctly decouple their biological sources only by the results of bio-chemical researches. Carbon isotopic studies of indi-vidual sedimentary lipid compounds can discover their genetic information, which pr…     

Differential retardation of organic matter maturation by overpressure

Thetraditionalhydrocarbongenerationmodeldoesnottakeintoaccounttheeffectofpressure[1].Astotheroleofpressureinorganicmattermaturationandpetroleumgeneration,threeconflictingopinionshaveeverbeenproposed:(1)Increasingpressurehasnodetectableeffectonorganic-mattermaturation[1,2];(2)increasingpressureenhanceshydrocarbon-thermaldestruction[3];(3)increasingpressuresignificantlyretardsorganic-mattermaturationandhydrocarbongeneration[4,5].Therearemorethan180overpressuredbasinsintheworld.Theroleofoverpress…     

济南、福山太阳辐射的气候学特征分析

利用济南、福山地面太阳辐射资料，分析了太阳辐射的气候变化特征。结果表明，60到90年代，济南地面太阳总辐射量、直接辐射量呈显著减少趋势，福山变化趋势不明显；90年代以后，济南地面太阳总辐射呈增多趋势。     

应用"极值剔除"和"逐步消空"法建立太原机场11月份辐射大雾预报指标集

本文介绍了利用“极值剔除”和“逐步消空”方法建立太原机场11月份辐射大雾预报指标集的具体过程，并对得出的预报指标进行回报检验，以证实其在业务中的切实可行性。     

98.7湖北特大暴雨的天气分析与降水模拟

1998年7月20～23日，湖北省南部发生了一次持续性特大暴雨过程，采用双向嵌套的非静力中尺度数值模式(MM5)对这次强暴雨过程进行初步模拟试验。结果表明，粗、细网格均能较好地模拟出雨带的走向和变动以及武汉地区的暴雨中心，尤其是嵌套域(细网格)模拟的降水强度比粗网格有明显改进，和实际观测结果更接近；另外，对引发这次特大暴雨的对流层低层的中尺度系统也能够很好地模拟出来。