Low Electrical Resistivity And Seismic Velocity At The Base Of The Upper Crust As Indicator Of Rheologically Weak Layer     

L. Vanyan  B. Tezkan  N. Palshin 《Surveys in Geophysics》2001,22(2):131-154

Conductivity models were compiled in two geological provinces with thinsediments. The first province is the margin of the Precambrian East EuropeanPlatform. The second one is the Phanerozoic Rhenish Massif as a part of CentralGermany Hercinicum. In both provinces, a conducting layer was revealed at thebase of the upper crust by the magnetotelluric soundings. Its depth is around10 km in the East European Platform and around 15 km in the Rhenish Massif.The conductance of the layer reaches a few tens of Siemens in the first provinceand is almost an order of magnitude greater in the second one.A good correlation between the conductor and a seismic wave-guide (low-velocityzone) exists at the base of the upper crust. Simultaneous decrease of both electricalresistivity and seismic velocity, suggests an increase of porosity and permeability inpresence of saline water. The depth of rheological weak layer in the PhanerozoicRhenish Massif corresponds to the commonly accepted depth of the thermallyinduced brittle/ductile transition. Contrary similar layer in the Precambrian EasternEuropean Platform is much shallower than the thermally induced transition. Somenew mechanism should be considered.  相似文献   

关于当代地球科学发展趋势的点滴认识     

吴凤鸣 《吉林地质》2001,20(4):4-6,32

面对资源、环境、人口、地质灾害等人类的生产、生活乃至生存的严峻危机，需要我们掌握地球内部的客观规律，不断更新和寻找地球科学理论和新的思维方式，掌握地球科学发展趋势，以协调好人与自然、人地关系及社会经济和可持续发展理论，造福于人类。  相似文献   

球面小波分析技术及在全球重力模型中的应用     

许惠平  刘万崧  R.H.N.Haagmans  A.J.Th.deBrnoue 《物探与化探》2001,25(1):8-13

在介绍球面小波理论的基础上,推导和比较了几种球面小波,分析了最新地球重力模型-EGM96,以此为依据,把球面小波多分辨分析用于计算全球自由空气异常及重力大地水准面,并对处理结果做出解释。  相似文献   

A Reliability Based Expert System for Assessment and Mitigation of Landslides Hazard Under Seismic Loading     

Al-Homoud  Azm S.  Tahtamoni  Wisam W. 《Natural Hazards》2001,24(1):13-51

Different models were developed for evaluating the probabilistic three-dimensional (3-D) stability analysis of earth slopes and embankments under earthquake loading using both the safety factor and the displacement criteria of slope failure.The probabilistic models evaluate the probability of failure under seismic loading considering the different sources of uncertainties involved in the problem. The models also take into consideration the spatial variabilities and correlations of soil properties. The developed models are incorporated in a computer program PTDDSSA.These analysis/design procedures are incorporated within a code named SARETL developed in this study for stability analysis and remediation of earthquake triggered landslides. In addition to the dynamic inertia forces, the system takes into consideration local site effects.The code is capable of assessing the landslide hazard affecting major transportation routes in the event of earthquakes and preparing earthquake induced landslide hazard maps (i.e., maps showing expected displacements and probability of slope/embankments failure) for different earthquake magnitudes and environmental conditions. It can also beused for proposing a mitigation strategy against landslides.  相似文献   

Detection of seepage paths in earth dams using self-potential and electrical resistivity methods   总被引：7，自引：0，他引：7  

T. V. Panthulu  C. Krishnaiah  J. M. Shirke 《Engineering Geology》2001,59(3-4):281-295

Earth and rockfill dams are designed to operate under steady state seepage. Anomalous seepage may be a threat to the integrity of the structure. In spite of advances made in the fields of geotechnical engineering, it is not possible to have 100% leak-proof structure. Any excessive and unplanned seepage may lead to the failure of the dam, especially in unconsolidated or fractured terrains. Geophysical methods play an important role in mapping seepage paths and monitoring the changes of the seepage with time, enabling to plan technically and economically worthwhile remedial measures. In the present paper, utilisation of electrical methods for delineation of seepage zones at two of the four Saddle dams of the Som-Kamla-Amba project, Rajasthan State, India; which is founded on heterogeneous rock mass, is discussed. Electrical resistivity method was used to delineate zones favourable for seepage, whereas, self-potential (SP) method was used to delineate the seepage paths. SP measurements have shown negative anomaly of the order of 10–20 mV in amplitude, indicating low seepage, coinciding with the seepage measurements made by the project authorities.  相似文献   

体应变观测中的气压干扰机制和排除方法的研究   总被引：7，自引：0，他引：7  

张凌空  何世海  刘北顺 《地震》1996,(2)

建立体应变理论气压干扰模型,通过实际观测资料研究了气压对体应变月变和日变的干扰过程,探讨消除干扰的方法,且和水位资料作了对比分析。  相似文献   

自转微椭、非均匀地球的潮汐变形   总被引：9，自引：3，他引：9       下载免费PDF全文

李国营  彭龙辉  许厚泽 《地球物理学报》1996,39(5):672-678

鉴于当前国际上关于自转微椭、非均匀地球（ＳＲＥＨＩ）的固体潮汐响应的结果之间存在明显分歧，特别是Ｌｏｖｅ数ｋ及重力潮汐因子δ对纬度的依赖情况截然不同，本文借助于摄动法与张量正则分量的广义球谐展开建立起来的侧向非均匀、自转微椭、粘弹地球的潮汐模拟理论，计算了ＳＲＥＨＩ地球的潮汐形变及相应的引力位变化．结果表明，描述径向位移的Ｌｏｖｅ数的纬度依赖部分系数ｈ＿＋与球对称部分ｈ＿０＋δｈ＿０之比不大于１．０‰；对Ｏ＿１波为０．２７‰；对Ｍ＿２波为０．１９‰；对Ｍ＿３波为０．４９‰；对Ｍ＿４波为０．８８‰．描述地球引力位变化的Ｌｏｖｅ数的纬度依赖部分系数ｋ＿＋与球对称部分ｋ＿０＋δｋ＿０之比小于３．０‰；对Ｏ＿１波为２．６７‰；对Ｍ＿２波为１．８９‰；对Ｍ＿３波为２．２４‰；对Ｍ＿４波为２．７０‰．  相似文献   

降雨对地电阻率干扰的分析   总被引：8，自引：0，他引：8  

张学民  郑慰坤 《华北地震科学》1996,14(4):71-75

在一些地电阻率观测台站受本身台址条件的限制，观测深度较浅，因此，观测值受到降雨等气象因素的影响。本文选取昌黎台ＥＷ向１９８３－１９９４年观测资料月均值，用褶积滤波和多元回归方法对ρｓ进行了降雨校正，将将之作为一个灰箱系统，将资料外推至１９９５４上，然后与原始观测值作残差分析，取得了一定效果。  相似文献   

The Coupled Re—Os and Pt—Os Systematics：A Theoretical Consideration     

熊永良  翟裕生 《中国地球化学学报》1995,14(1):52-59

The ^190Pt-^186Os system should be a unique tracer for mantle processes be-cause both Pt and Os are concentrated in the mantle.The ^190Pt-^186Os system will also be a good supplement to the ^187Re-^187Os system for dating and tracing mantle pro-cesses because the ^190Pt-^186Os system is not so easily contaminated by crustal materials as the ^187Re-^187Os system.In turn,the application of the ^187Re-^187Os system to Pt-enriched materials uncontaminated by crustal materials will indirectly refine the half life of ^190Pt.The ^190Pt is refined.In the coupled ^187Re-^187Os and ^190Pt-^186Os sys-tematics,an ^186Os*/^190Pt-^187Os*/^187Re Concordia diagram similar to the ^206Pb*/^238U-^208Pb*/^232Th Concordia can be constructed.In such a Concordia diagram,a date will be obtained so long as the ^190Pt-^186Os system remains closed even if the ^187Re-^187Os sys -tem is contaminated by crustal materials.In addition ,for the coupled ^190Pt-^186Os and ^187Re-^187Os systematics,the mantle processes and the interactions between the mantle and the crust will be described by two ratios:^186Os/^188Os and ^187Os/^188Os .The coupled ^187Re-^187Os and ^190Pt-^186Os systematics will be a powerful tool in the investigation of the geodynamic history of the Earth because the ^187Re-^187Os system is sensitive to the interactions between the mantle and the crust,while the ^190Pt-^186Os system is a good tracer for mantle processes.  相似文献   

“数字地球”科学工程   总被引：10，自引：0，他引：10  

崔伟宏  李小娟 《地球信息科学学报》1999,1(1):36-41

“数字地球”是集科学、技术和工程于一体的一项宏伟的科学体系。“数字地球”由基础研究、技术支撑和科学工程三部分组成,其中科学工程是“数字地球”的核心和目标。文章在我国“数字地球”科学工程现状分析的基础上,结合国情,对我国“数字地球”科学工程的发展提出了建议。  相似文献