Probabilistic modeling of seismically triggered landslides using Monte Carlo simulations

The 2004 Chuetsu earthquakes of Niigata (Japan) triggered numerous landslides, and the most widespread types of landslides were highly disrupted, relatively shallow slides and soil (debris) flows. This paper presented a method to evaluate slope instability using Newmark displacement on a pixel-by-pixel basis in a given area. The proposed method was able to integrate Newmark displacement modeling and Monte Carlo simulations within geographical information systems. In the modeling, an empirical attenuation relationship was utilized to calculate Arias intensity over this study area, and the variability of geotechnical parameters was taken into account to calculate coseismic landslide displacement. Before deriving the displacement from related inputs, the Monte Carlo simulations ran 1,500 times and generated 1,500 displacement values for each grid cell, and then means and standard deviations of displacement were calculated and probabilistic distributions can be obtained. Finally, given 10 cm as a threshold value of displacement, estimated probabilities of displacement exceeding 10 cm were shown as a map of seismic landslide hazards. The resulting hazard map was classified into four categories from very low to high level.     

煤层气固井声幅测井方法探讨

影响煤层气固井声幅测井的因素较多,如地层软硬变化大、套管内径或壁厚不均、仪器不居中、发射能量不足、接收灵敏度不够等,这些因素的存在将会导致首波丢失、时差曲线产生周波跳跃或波动现象。为提高煤层气固井声幅测井质量,要尽量保证所用仪器外径接近套管内径,以减少无效传播和能量损失,另外需提高仪器的发射能量及接收灵敏度;在自由套管和声波强吸收地层,必须保证自由套管首波不限幅、声波强吸收地层首波不丢失。在现场解释时,一般以＂自由套管＂处的偏转幅度值A为标准,将固井声幅曲线幅度的20%A和40%A作为分界点,评价固井效果。     

Climate change in Mt. Qomolangma region since 1971

Using monthly average, maximum, minimum air temperature and monthly precipitation data from 5 weather stations in Mt. Qomolangma region in China from 1971 to 2004, climatic linear trend, moving average, low-pass filter and accumulated variance analysis methods, the spatial and temporal patterns of the climatic change in this region were analyzed. The main findings can be summarized as follows: (1) There is obvious ascending tendency for the interannual change of air temperature in Mt. Qomolangma region and the ascending tendency of Tingri, the highest station, is the most significant. The rate of increasing air temperature is 0.234 oC/decade in Mt. Qomolangma region, 0.302 oC/decade in Tingri. The air temperature increases more strongly in non-growing season. (2) Compared with China and the global average, the warming of Mt. Qomolangma region occurred early. The linear rates of temperature increase in Mt. Qomolangma region exceed those for China and the global average in the same period. This is attributed to the sensitivity of mountainous regions to climate change. (3) The southern and northern parts of Mt. Qomolangma region are quite different in precipitation changes. Stations in the northern part show increasing trends but are not statistically significant. Nyalam in the southern part shows a decreasing trend and the sudden decreasing of precipitation occurred in the early 1990s. (4) Compared with the previous studies, we find that the warming of Mt. Qomolangma high-elevation region is most significant in China in the same period. The highest automatic meteorological comprehensive observation station in the world set up at the base camp of Mt. Qomolangma with a height of 5032 m a.s.l will play an important role in monitoring the global climate change.     

吉林伊通盆地莫里青断陷古近系双阳组储集层成岩作用研究

古近系双阳组是在吉林省伊通盆地莫里青断陷中，油气赋存的主要层位,储层主要为湖底扇和扇三角洲的砂体。依据双阳组储层的大量薄片、扫描电镜、粘土矿物分析的资料研究了该储集层的成岩作用。研究结果表明双阳组储集层：成岩作用经历了压实、压溶、胶结、交代和溶解6方面的作用。双储集层中的自生粘土矿物蒙皂石向伊利石转化具有明显的特征：主要演化过程经历了蒙皂石渐变带，第一迅速转化带和第二迅速转化带，相应的成岩作用阶段可划分为早成岩阶段B期、晚成岩阶段A1期和晚成岩阶段A2期。依据在垂向上的成岩变化,建立了莫里青断陷双阳组储集层的成岩作用演化序列。在垂向上成岩作用的类型和强度均存在明显的差异，造成了储层物性的垂向分带。     

基于遥感信息的华北冬小麦区域生长模型及模拟研究

卫星遥感估产和作物生长模拟在作物监测和产量预测方面有各自不可替代的优势。但是,遥感估产难以揭示作物生长发育和产量形成的内在机理,作物模拟在区域应用时初始值的获取和参数的区域化遇到很多困难。如何利用二者的互补性使其相互结合受到人们关注。该文在Wofost模型本地化和区域化的基础上,首次利用同化法的思路探讨了MODIS遥感信息与华北冬小麦生长模拟模型结合的可行性和方法,初步建立了潜在生产水平(水分适宜条件)下区域遥感-作物模拟框架模型(WSPFRS模型)。模拟结果显示:WSPFRS模型对区域尺度的出苗期重新初始化后,模拟的开花期、成熟期空间分布的准确性比Wofost模拟结果有所改进;利用遥感信息对区域尺度上返青期生物量重新初始化后,模拟贮存器官干重的空间分布更接近实际单产的分布,贮存器官干重的高值区与实际高产区基本相符。该研究将为下一步实际水分供应条件下基于遥感信息的冬小麦区域生长模拟研究奠定了基础。     

^40Ar／^39Ar Fast Neutron Activation Ages of Quartz from the Jinman Vein Copper Dposit in Western Yunnan and Their Significance

Quartz samples collected from the Jinman vein copper deposit in the Lanping Basin of western Yunnan were determined by⁴⁰Ar/³⁹Ar fast neutron activation techniques, and the spectra are characterized as being saddle-shaped. The samples yielded a plateau age of 58.05 ± 0.54 Ma, a minimum appearance age of 56.76 ±0.81 Ma and an isochron age of 54.30 ± 0.15 Ma, the three ages being close to each other, indicating that the ages of the quartz samples so far determined are true and reliable. The plateau age represents the time of formation of Cu-bearing quartz veins, which is corresponding to Early Himalayan. This age is also consistent with the time at which a tectonically thermal event (60 Ma) took place within the Lanping Basin, Yunnan Province. In consideration of the fact that copper ore and other ore types in the vast area of western Yunnan are concentrated mainly in the Early Himalayan strata, the authors believe that there must have existed some indispensable key factors leading to metallogenesis on a large scale during the Early Himalayan period in western Yunnan and also constraining in union the formation of ore deposits there.     

基于图论的树状河系结构化绘制模型研究

结合树状河系自身的结构特点和图论的思想，提出了基于图论的河系结构化绘制模型的建立，利用图论的思想描述了河系的结构并建立其自动符号化模型，阐述了主流、流向自动确定和结构化绘制实现的详细算法，并对通用图形数据格式DXF文件记录的河系数据进行了测试。     

Laboratory Simulation of the Formation Process of Surface Geochemical Anomalies Applied to Hydrocarbon Exploration

The formation mechanisms and processes of geochemical anomalies used as proxies in surface geochemistry exploration (SGE) have not been well understood. Previous studies cannot realize 3D measurement of microseeping hydrocarbons from reservoirs to the surface, which made it difficult to understand the features and pathways of deep hydrocarbon microseepages. Understanding the processes of hydrocarbon microseepages will contribute to the acceptance and effectiveness of surface geochemistry. Based on a simplified geological model of hydrocarbon microseepages, including hydrocarbon reservoir, direct caprock, overlying strata and Quaternary sediments, this work established a 3D experimental system to simulate the mechanisms and processes of deep hydrocarbon microseepes extending to the surface. The dispersive halos of microseeping hydrocarbons in the subsurface were adequately described by using this 3D experimental system. Results indicate that different migration patterns of hydrocarbons above the point gas source within the simulated caprock and overlying strata can be reflected by the ratio of i-butane to n-butane (i-C4/n-C4), which follow diffusion and infiltration (buoyancy) mechanisms. This is not the case for vertical measurement lines far from the point gas source. A vertical gas flow in the form of a plume was found during hydrocarbon microseepage. For sampling methods, the high-density grid sampling is favorable for delineating prospecting targets. Hydrocarbon infiltration or buoyancy flow occurs in the zones of infiltration clusters, coupling with a diffusion mechanism at the top of the water table and forming surface geochemical anomalies. These results are significant in understanding hydrocarbon microseepage and interpreting SGE data.     

桂西地区二叠系合山组铝土岩的沉积环境*

桂西地区二叠系合山组铝土岩的沉积环境存在海相、陆相之争。通过对桂西二叠系铝土岩的区域调查及钻孔样品微量元素地球化学数据的分析,认为桂西二叠系铝土岩产出于陆相环境。从铝土岩分布情况看,桂西二叠纪各孤立碳酸盐岩台地上均广泛分布铝土岩沉积,该区域产出特征证明矿层是在碳酸盐岩台地全部暴露地表的环境下形成的。从铝土岩层与下伏茅口组灰岩的接触关系来看,铝土岩层底部存在茅口组灰岩砾石,在部分剖面尚见下伏茅口组灰岩中充填铝土岩等现象,说明铝土岩矿化过程直接于茅口组灰岩的古喀斯特面上完成。此外,在矿层中发现古植物根茎化石也是铝土岩形成于陆相环境的有力证据。从微量元素地球化学结果来看,来自铝土岩层样品的硼含量均小于10×10^-6,Sr/Ba值范围为0.29~1.61,平均值为0.92,Rb/K值范围为0.0011~0.0025,平均值为0.0017,以上指标结合V/Zr-Zr/Cu图解的判别,结果均指示铝土岩形成于陆相淡水环境。     

Indicator-based spatiotemporal characteristics of apple drought in North China

Natural Hazards - Frequent occurrences of drought stress caused by dry weather create severe destroy in apple yield and quality in North China. Although appropriate drought stress is beneficial to...