New method for in situ characterization of loose material for landslide mapping purpose     

Adrien Pantet  Aurle Parriaux  Philippe Thelin 《Engineering Geology》2007,94(3-4):166-179

The assessment of grain size distribution and plasticity of loose geological material, during in situ geological investigations, is not obvious. Visual appreciation allows an approximative quantification of the coarse granulometric fractions, but not of the fine ones. Field soils determination methods suggested until now, are visual and tactile tests leading to a very rough estimate, which is only qualitative and not very reproducible. The new proposed field test (GEOLEP method) allows a quick quantification of the fine fraction of loose material. It allows the determination of the sand fraction (fine and medium grained sands) as well as the methylene blue value of the samples. The necessary equipment to perform this test is light and compact and the time needed to analyze one sample is approximately 15 min. Thus it is also possible to carry out numerous measurements in one day. The calibrations were carried out on a selection of 13 natural samples, chosen for their representativeness of the typical alpine quaternary deposits. The results obtained with GEOLEP method are relevant compared with standardized laboratory tests; the obtained correlation indexes are of 73% for the comparison with laboratory stain test results and of 89% with a laboratory method using a similar procedure than the field test. The correlation we performed with Atterberg's limits tests shows that a rough approximation of plasticity index can also be obtained (R² = 75%). This method thus brings a new tool which should allow taking into account the lithological factor (by some quantitative and representative variables) in a reliable way for the evaluation of landslide hazards.  相似文献   

西安地区部分古遗址考古地磁研究          下载免费PDF全文

孟昭秦 《地质科学》1998,33(4):489-493

通过对陕西耀州窑遗址内4个古窑,临潼兵马俑一号坑,西铜一级公路经过黄堡工地开挖的两个五代窑,以及耀州窑博物馆仓库工地内开挖的一个金代窑和一个春秋窑遗址的古地磁研究,初步得出了西安地区古地磁场变化的规律,为鉴定从春秋到金代西安地区的古遗址、古文物提供了考古地磁学上的一个粗略的标准。  相似文献   

Microclimatic characterization of a karstic cave: human impact on microenvironmental parameters of a prehistoric rock art cave (Candamo Cave, northern Spain)   总被引：2，自引：0，他引：2  

M. Hoyos  V. Soler  J. C. Cañaveras  S. Sánchez-Moral  E. Sanz-Rubio 《Environmental Geology》1998,33(4):231-242

The Candamo Cave contains an important group of paleolithic paintings which have been seriously deteriorated due to mass tourism. In this work, an analysis was carried out of different climatic parameters (CO₂, temperature, humidity, ²²²Rn) during annual cycles with the cave closed to the public and during an experimental period of controlled visits. The effect of visits on the geochemical characteristics of karstic water was also analyzed together with the cave ventilation. The natural variations in the cave air CO₂ were above 3000 ppm, the increase produced through visits was only 100–110 ppm and since the humidity is almost permanently at saturation point, the critical parameter which limits the visitor capacity becomes air temperature. The temperature changes during the annual cycle are of the order of 1  °C in the external part and less than 0.5  °C in the internal part of the cave and a maximum increase of 0.13  °C was observed during the period of the visits. The ²²²Rn and CO₂ concentration minimums in the summer period (July–October) show that this is the most propitious time for visits, since the greatest ventilation is produced in the cave at this time and, therefore, the greatest capacity for recovery. The geochemistry of the water, on the other hand, indicated that this is the period of the year in which processes of wall corrosion can be most easily introduced, although this would be of limited magnitude. The visitor capacity calculated was 29 visitors/day. Received: 29 August 1996 · Accepted: 23 June 1997  相似文献   

自然灾害复杂性研究   总被引：32，自引：5，他引：27  

魏一鸣 《地理科学》1998,18(1):25-31

从自然灾害系统的观点出发,阐述了自然灾害系统的特点,提出了自然灾害复杂性的概念。基于前人研究的一些成果,讨论了分形,混沌,人工神经网络等非线性理论以及定性与定量综合集成技术在自然灾复杂性研究中的应用。  相似文献   

中国传统民居建筑文化的自然地理背景   总被引：17，自引：0，他引：17  

沙润 《地理科学》1998,(1)

讨论了气候、地貌与水文、地质与植被等自然地理要素对中国传统民居建筑的格局、型式、风格、特色等方面的影响。在此基础上分析了以功利观、审美观和生态观为内涵的中国传统民居建筑文化的自然观。  相似文献   

自然类比法对张北──尚义6.2级地震序列类型和震后趋势早期判断实例     

焦远碧 《高原地震》1998,(1)

用自然类比法对1998年1月10日张北─尚义6．2级地震序列类型和震后趋势进行了早期判断,找出了与之最相似的四个序列是1976年9月23日巴音木仁6．2级地震（S17）、1996年5月3日包头6．4级地震（558）、1985年4月18日禄劝6．3级地震（S34）和1984年5月21日南黄海6．0级地震（S33）。由此判断张北地震序列为主震余震型,推算最大余震震级应在4．3～4．7之间,一个月内4级以上余震数可能在11～22次之间。实测结果张北地震最大余震震级4．6,一个月内4级以上余震数18次,均在预测范围内。  相似文献   

Monitoring,causality, and uncertainty in a stratospheric context     

A. Barrie Pittock 《Pure and Applied Geophysics》1980,118(1):643-660

Our increasingly complex understanding of stratospheric chemistry and transport processes leaves us with various theoretical possibilities of appreciable and perhaps serious environmental impact due to human activities. These possibilities raise policy questions in which the economic and other costs of regulating human activities must be weighed against the possible consequences of no such regulation. The natural variability of the atmosphere, the physical and other limitations on our global sampling and monitoring abilities, and the difficulties in establishing causal connections leave us in a state of uncertainty as to the reality and magnitude of at least some of these theoretical environmental impacts. Policy-makers must make decisions in the face of these uncertainties.The proper role of scientists as such in narrowing and quantifying the uncertainties is discussed, with particular regard to the evidence that cultural and other biases often affect individual scientists' conclusions. Conscious efforts are needed to minimize bias, quantify uncertainties, and speed up the process of scientific consensus-building. A careful distinction should be drawn between scientifically determined probabilities, and cost-benefit analyses which necessarily involve value judgments.  相似文献   

The role of social norms in climate adaptation: Mediating risk perception and flood insurance purchase     

Alex Y. Lo 《Global Environmental Change》2013,23(5):1249-1257

Flood insurance plays an important role in climate adaptation by recovering insured losses in the event of catastrophic flooding. Voluntary adoption of flood insurance has been seen as a function of risk perception that is shaped by social norms. This paper attempts to clarify the relationship between these factors. It is based on a household survey conducted in the eastern cities of Australia and involving a total of 501 randomly selected residents. Results of a path analysis show that the likelihood of having flood insurance cover was associated with perceived social norms, but not perceived flood risk. In addition, perceived norms and risk were statistically related to each other. It is concluded that social norms played a mediating role between insuring decision and risk perception. Risk perception might influence the insuring decision indirectly through shaping perception of social norms. This implies that adaptive behaviour is not necessarily a function of risk perception, but an outcome of its impacts upon the ways in which the individuals situate themselves in their social circles or the society. There is a feedback process in which individual perceptions of risk manifest as both a cause and effect, shaping and being shaped by the socio-cultural context.  相似文献   

Oil migration driven by exhumation of the Canol Formation oil shale: A new conceptual model for the Norman Wells oil field,northwestern Canada     

《Marine and Petroleum Geology》2015

Thermal history, petroleum system, structural, and tectonic constraints are reviewed and integrated in order to derive a new conceptual model for the Norman Wells oil field, and a new play type for tectonically active foreland regions. The thermal history recorded by Devonian rocks suggests that source rocks experienced peak thermal conditions in the Triassic–Jurassic, during which time oil was likely generated. After initial oil generation and expulsion, the Canol Formation oil shale retained a certain fraction of hydrocarbons. The shallow reservoir (650–350 m) is a Devonian carbonate bank overlain by the Canol Formation and resides within a hanging wall block of the Norman Range thrust fault. Both reservoir and source rocks are naturally fractured and have produced high API non-biodegraded oil. Thrust faults in the region formed after the Paleocene, and a structural cross-section of the field shows that the source and reservoir rocks at Norman Wells have been exhumed by over 1 km since then.The key proposition of the exhumation model is that as Canol Formation rocks underwent thrust-driven exhumation, they crossed a ductile–brittle transition zone and dip-oriented fractures formed sympathetic to the thrust fault. The combination of pore overpressure and new dip-directed subvertical fractures liberated oil from the Canol Formation and allowed for up-dip oil migration. Reservoir rocks were similarly fractured and improved permeability enhanced charging and pooling of oil. GPS and seismicity data indicate that strain transfer across the northern Cordillera is a response to accretion of the Yakutat terrane along the northern Pacific margin of North America, which is also the probable driving force for foreland shortening and rock exhumation at Norman Wells.  相似文献   

曹县梁堤头地区第四系地裂缝成因及防治          下载免费PDF全文

冯超臣  黄文峰  郑秀荣 《山东国土资源》2015,31(5)

鲁豫交界的曹县黄河故道地区,地势较高的自然堤堤缘区是地裂缝等地质灾害的高发区。地裂缝主要由地表厚粘土层干湿胀缩产生,有一定的隐蔽性,并受地形和大气影响。地下水动态变化对地裂缝影响不大。地表裂隙张力的直接作用、建筑物的非均质土地基不均匀沉陷等因素的存在共同导致了该区民房开裂。可以采取加固地基和搬迁避让等方法进行防治。  相似文献