柴达木盆地三湖地区磁力异常形成机理研究与异常分析   总被引：1，自引：0，他引：1       下载免费PDF全文

王志强  王财富  徐子远  李瑞 《地质找矿论丛》2008,23(4):339-342,347

柴达木盆地的油气资源丰富,近年来在该区发现了大量异常显示,但是各种异常形成机理各不相同,存在较大多解性,使得该区油气储量探明率很低.根据柴达木盆地以往开展的常规非地震勘探的现状及效果,以磁测找油机理为基础,采用磁力资料化极、剩余磁力异常提取和磁力平剖图等处理手段,对三湖地区生物气藏磁异常进行分析研究,取得明显的异常显示效果.  相似文献   

红旗渠任村镇白家庄至尖庄段一带地质灾害体特征及其稳定性评价     

尹红美  魏永齐  王培 《地下水》2008,30(6)

红旗渠是举世文明的引水工程,全长4 013.6 km.红旗渠沿线地质条件极为复杂,地质灾害频繁发生.林州市任村镇白家庄至尖庄一带为本次工作的勘查区,勘查中共发现零星崩塌3处,崩塌带1处、沟谷泥石流3处.本文针对发现的地质灾害的类型、规模、形态等进行描述并给以稳定性评价.  相似文献   

广东省五华县地质灾害形成特征及防治对策   总被引：6，自引：0，他引：6  

罗迎新 《中国地质灾害与防治学报》2008,19(3):96-101

五华县主要地质灾害类型有滑坡、崩塌、地面塌陷、水土流失等。其中以滑坡、崩塌为主,多分布在东南、南部花岗岩区、北部花岗岩风化土区等广大中低山及丘陵区,具有点多面广,灾害点个体规模小,稳定性差,活动频繁,地质灾害发育呈明显的地域性与季节性分布等特点。五华县地质灾害的形成与发生是多种致灾因素相互作用的结果。地层岩性是其形成的内在要素,它在一定程度上决定着地质灾害的发育程度与类型;地形地貌与植被是地质灾害形成的外在条件,它制约着崩、滑、塌等致灾地质作用的形成;大气降雨是地质灾害形成与发生的激发因素,决定着地质灾害发生的速度和时间;人类工程活动是影响地质灾害形成与发生的最主要、最直接的因素。对地质灾害的防治应采用避让、预防、监测及治理措施,做到避让与治理结合,以群测群防为基本手段,点状灾害以工程治理与生物防治为主;面状灾害以生物防治为主;采用点、面结合综合治理的方法。  相似文献   

矿泉水常识问答     

葛文彬  杨敏 《四川地质学报》2008,28(2):160-163

矿泉水中的饮用天然矿泉水在地下深循环条件下形成,化学成分稳定,水源卫生,细菌学指标安全。有一定含量的矿物盐、微量元素或二氧化碳气体,作为一种天然饮料,是其他饮用水无法比拟的,无须医生指导,长期饮用也不会对人体产生危害。  相似文献   

吉林省江源县地质灾害发育特征及防治对策     

孙秀菲  刘永贵  李忠水  王长江 《地质灾害与环境保护》2008,19(4):21-24

江源县位于吉林省东南部,处于长白山西麓,行政管辖隶属于吉林省白山市,具有丰富的矿产和旅游资源。近年来,由于经济的发展和人类工程活动的增强,加剧了区内地质灾害的形成,地质灾害对当地的经济发展和人民生命财产安全造成损失和潜在威胁。本文对该县的地质环境作了详尽的阐述,在此基础上对研究区内的泥石流、滑坡、地面塌陷、不稳定斜坡等地质灾害的发育特征和形成条件作了全面的分析研究,总结出它们的发展规律,同时对该县进行了地质灾害经济损失现状评估和预测评估,最后结合当地经济条件与地质灾害现状,给出了较为切实可行的地质灾害防治对策。  相似文献   

基于层次分析法的可拓学理论在山区公路泥石流危险性评价中的应用     

罗冠枝  徐林荣 《地质灾害与环境保护》2008,19(4):128-133

基于可拓工程方法,在物元模型理论的基础上建立了公路泥石流危险性评价的物元模型,并采用层次分析法计算物元模型中各评价指标的权系数。通过实际公路泥石流危险性等级的关联度计算,对四川地区雅泸高速公路的5条泥石流沟进行了评价,得出与实际相符合的结论。并与其他评价方法相比表明：该方法不仅可以应用在泥石流危险性评价上,而且所得的结果会更加合理,具有较好的适用性。  相似文献   

The discovery of metal trace elements in natural gas and its ecologic environmental significance.     

WANG Che-Xi DENG Mei-Zhou LIU Ying-Han LIU E-Wei LI Nie-Yun LU Ren-Ji 《地学前缘》2008,15(6):124

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焦作-郑州天然气输气管道工程地质灾害防治措施及防治建议     

朱洪生  田东升  刘占时  王建华 《安徽地质》2008,18(4):307-310

焦作-郑州天然气输气管道是较重要建设项目,输气管道起自焦作市博爱县磨头镇,南止郑州市惠济区古荥镇,该输气管道沿线地质环境条件复杂程度为简单-中等。地质灾害类型主要为崩塌、地裂缝、地面不均匀沉陷,黄土湿陷和沙土液化等地质灾害。工程建设有引发和加剧崩塌灾害的可能性,有遭受地质灾害的危险性。工程建设过程中应针对不同的灾害类型采取适当的预防或治理措施。  相似文献   

The dynamics and thermodynamics of large ash flows   总被引：6，自引：6，他引：0  

Marcus I. Bursik  Andrew W. Woods 《Bulletin of Volcanology》1996,58(2-3):175-193

 Ash flow deposits, containing up to 1000 km³ of material, have been produced by some of the largest volcanic eruptions known. Ash flows propagate several tens of kilometres from their source vents, produce extensive blankets of ash and are able to surmount topographic barriers hundreds of metres high. We present and test a new model of the motion of such flows as they propagate over a near horizontal surface from a collapsing fountain above a volcanic vent. The model predicts that for a given eruption rate, either a slow (10–100 m/s) and deep (1000–3000 m) subcritical flow or a fast (100–200 m/s) and shallow (500–1000 m) supercritical flow may develop. Subcritical ash flows propagate with a nearly constant volume flux, whereas supercritical flows entrain air and become progressively more voluminous. The run-out distance of such ash flows is controlled largely by the mass of air mixed into the collapsing fountain, the degree of fragmentation and the associated rate of loss of material into an underlying concentrated depositional system, and the mass eruption rate. However, in supercritical flows, the continued entrainment of air exerts a further important control on the flow evolution. Model predictions show that the run-out distance decreases with the mass of air entrained into the flow. Also, the mass of ash which may ascend from the flow into a buoyant coignimbrite cloud increases as more air is entrained into the flow. As a result, supercritical ash flows typically have shorter runout distances and more ash is elutriated into the associated coignimbrite eruption columns. We also show that one-dimensional, channellized ash flows typically propagate further than their radially spreading counterparts. As a Plinian eruption proceeds, the erupted mass flux often increases, leading to column collapse and the formation of pumiceous ash flows. Near the critical conditions for eruption column collapse, the flows are shed from high fountains which entrain large quantities of air per unit mass. Our model suggests that this will lead to relatively short ash flows with much of the erupted material being elutriated into the coignimbrite column. However, if the mass flux subseqently increases, then less air per unit mass is entrained into the collapsing fountain, and progressively larger flows, which propagate further from the vent, will develop. Our model is consistent with observations of a number of pyroclastic flow deposits, including the 1912 eruption of Katmai and the 1991 eruption of Pinatubo. The model suggests that many extensive flow sheets were emplaced from eruptions with mass fluxes of 10⁹–10¹⁰ kg/s over periods of 10³–10⁵ s, and that some indicators of flow "mobility" may need to be reinterpreted. Furthermore, in accordance with observations, the model predicts that the coignimbrite eruption columns produced from such ash flows rose between 20 and 40 km. Received: 25 August 1995 / Accepted: 3 April 1996  相似文献   

Bayesian estimation of seismic hazard for two sites in Switzerland     

Erik Rüttener  Juan José Egozcue  Dieter Mayer-Rosa  Stephan Mueller 《Natural Hazards》1996,14(2-3):165-178

Seismic hazard analysis is based on data and models, which both are imprecise and uncertain. Especially the interpretation of historical information into earthquake parameters, e.g. earthquake size and location, yields ambiguous and imprecise data. Models based on probability distributions have been developed in order to quantify and represent these uncertainties. Nevertheless, the majority of the procedures applied in seismic hazard assessment do not take into account these uncertainties, nor do they show the variance of the results. Therefore, a procedure based on Bayesian statistics was developed to estimate return periods for different ground motion intensities (MSK scale).Bayesian techniques provide a mathematical model to estimate the distribution of random variables in presence of uncertainties. The developed method estimates the probability distribution of the number of occurrences in a Poisson process described by the parameter . The input data are the historical occurrences of intensities for a particular site, represented by a discrete probability distribution for each earthquake. The calculation of these historical occurrences requires a careful preparation of all input parameters, i.e. a modelling of their uncertainties. The obtained results show that the variance of the recurrence rate is smaller in regions with higher seismic activity than in less active regions. It can also be demonstrated that long return periods cannot be estimated with confidence, because the time period of observation is too short. This indicates that the long return periods obtained by seismic source methods only reflects the delineated seismic sources and the chosen earthquake size distribution law.  相似文献