Landslide susceptibility assessment using evidential belief function,certainty factor and frequency ratio model at Baxie River basin,NW China

This study evaluates and compares landslide susceptibility maps of the Baxie River basin, Gansu Province, China, using three models: evidential belief function (EBF), certainty factor (CF) and frequency ratio (FR). First, a landslide inventory map is constructed from satellite image interpretation and extensive field data. Second, the study area is partitioned into 17,142 slope units, and modelled using nine landslide influence parameters: elevation, slope angle, slope aspect, relief amplitude, cutting depth, gully density, lithology, normalized difference vegetation index and distance to roads. Finally, landslide susceptibility maps are presented based on EBF, CF and FR models and validated using area under curve (AUC) analysis. The success rates of the EBF, CF and FR models are 0.8038, 0.7924 and 0.8088, respectively, while the prediction rates of the three models are 0.8056, 0.7922 and 0.7989, respectively. The result of this study can be reliably used in land use management and planning.     

Theoretical and quantitative analyses of the fault slip rate uncertainties from single event and erosion of the accumulated offset

Fault slip rate is one of the most important subjects in active tectonics research, which reveals the activity and seismic potential of a fault. Due to the improvement of dating precision with the development of dating methods, Holocene geological markers, even the young markers of thousands or hundreds of years old, are widely used in fault slip rate calculation. Usually, uncertainties from a single event and erosion of the accumulated offsets are involved in fault slip rate determination. Two types of uncertainties are related to a single event; the first is the time elapsed since the latest (the most recent) event; the second is the period since the formation of the geological marker to the occurrence of the first event. High‐slip‐rate faults are more sensitive to these uncertainties than low‐slip‐rate faults. In this study, we studied quantitatively the effects of a single event on fault slip rate following the three classic earthquake models: the characteristic earthquake, uniform slip and variable slip models. We suggest that the erosion of the accumulated offset–lateral erosion on a strike‐slip fault, should also be considered in fault slip estimation. Therefore, we propose a differential method to obtain a reliable fault slip rate. In the differential method, the slip rate is the ratio of offset differentials and corresponding age differentials between the older and younger terraces along strike‐slip faults. This kind of differential method could avoid the uncertainties from the first and latest events, as well as that from the lateral erosion. By applying the differential method, we got the revised slip rates of ∼5–10 mm/year on the Altyn Tagh and Kunlun faults. These low slip rates could fit previous geodetic and geological fault slip rates and shortening rates as well as the millennial recurrence intervals of strong earthquakes along the major segments of these faults.     

The method of fundamental solution for 3‐D wave scattering in a fluid‐saturated poroelastic infinite domain

By using a complete set of poroelastodynamic spherical wave potentials (SWPs) representing a fast compressional wave P_I, a slow compressional wave P_II, and a shear wave S with 3 vectorial potentials (not all are independent), a solution scheme based on the method of fundamental solution (MFS) is devised to solve 3‐D wave scattering and dynamic stress concentration problems due to inhomogeneous inclusions and cavities embedded in an infinite poroelastic domain. The method is verified by comparing the result with the elastic analytical solution, which is a degenerated case, as well as with poroelastic solution obtained using other numerical methods. The accuracy and stability of the SWP‐MFS are also demonstrated. The displacement, hoop stress, and fluid pore pressure around spherical cavity and poroelastic inclusion with permeable and impermeable boundary are investigated for incident plane P_I and SV waves. The scattering characteristics are examined for a range of material properties, such as porosity and shear modulus contrast, over a range of frequency. Compared with other boundary‐based numerical strategy, such as the boundary element method and the indirect boundary integral equation method, the current SWP‐MFS is a meshless method that does not need elements to approximate the geometry and is free from the treatment of singularities. The SWP‐MFS is a highly accurate and efficient solution methodology for wave scattering problems of arbitrary geometry, particularly when a part of the domain extends to infinity.     

东南太平洋热液区硫化物样品富集培养物中Fe3＋还原细菌的多样性分析

采集了东南太平洋热液区DYl15-20V一$35一TVGl7站位的沉积物硫化物样品,其含有76．717％（m／m）强还原性的磁性良好的黄铁矿．以乳酸钠为电子供体,不溶性的氢氧化铁为电子受体,对该样品进行Fe¨还原细菌的定向富集培养．通过构建该茵群的16SrDNA基因文库,随机挑选82个阳性克隆子进行群落结构多样性分析．研究结果表明：82个克隆代表的6种基因型分别属于4个主要类群,其中ε一变形杆菌占有绝对优势,达到55．2％．此外其还包括厚壁菌门、β一变形杆菌和仅．变形杆菌,克隆子比例依次为27．6％、10．3％、6．9％．在富集产物中还原氢氧化铁的功能菌群主要是具有硫还原作用的ε一变形菌中的硫还原菌．     

LiDAR技术在活动构造研究中的应用

沿断裂带的大比例尺地貌填图是活动构造研究的重要基础。传统方法一般通过遥感、航片解译以及典型地点的实地测量进行详细填图。因此传统方法一般只能获得二维变形特征,或者局部的三维变形。激光雷达测量(Light Detection And Ranging-LiDAR)技术优势为对地貌的高精度、全方位、三维直接测量,可以为活动构造研究提供沿整条断裂带的高精度地貌高程基础数据。基于LiDAR数据的量化分析是未来活动构造研究的趋势。目前,美国、欧洲、日本以及我国台湾地区等均已经开展沿主要活动断裂带的大规模机载LiDAR测量。与传统方法相比,LiDAR技术在森林覆盖区和城区的活动断裂填图中具有巨大的优势,在沿断裂位错测量上也更精准,更有效。并且震前与震后LiDAR数据对比也是研究同震变形特征、探索断裂发震模式的重要手段。本文综述LiDAR技术在活动构造研究中的主要应用,介绍LiDAR技术在活动构造研究中的优势与前景。分析表明,激光雷达技术在活动构造研究中的应用势在必行,沿国内主要活动断裂带的机载LiDAR测量将成为未来国内活动断裂研究基础数据获取的重要手段。     

云南江城钾盐基准井钻进工艺分析

云南江城钾盐基准井位于思茅凹陷东区南部向斜翼部两条断层交汇处,构造相对发育,岩石破碎。其施工目的主要目的是通过取心钻进获取＂中、新生代＂含盐建造完整的地层序列,建立一个可供找钾参照的＂标杆地层柱＂。其施工的难点是上部地层以石英砂岩为主,与泥岩互层,泥岩较软、易水化、难取心;砂岩坚硬、研磨性强;下部地层主要以泥岩为主夹薄层砂岩,泥岩致密硬脆,在孔底呈弹塑性,可钻性极差。通过选择合理的钻井设备,优化钻具组合,制订切合实际的钻进参数,采用镁基盐水钻井液,进行川-74取心筒传统取心和绳索取心钻进,获得了盐矿心无溶蚀现象,井眼轨迹和岩心采取率均达到设计要求的较好效果。     

The existence of a Smale horseshoe in a planar circular restricted four-body problem

In this paper we study the existence of a Smale horseshoe in a planar circular restricted four-body problem. For this planar four-body system there exists a transversal homoclinic orbit, but the fixed point is a degenerate saddle, so that the standard Smale–Birkhoff homoclinic theorem cannot be directly applied. We therefore apply the Conley–Moser conditions to prove the existence of a Smale horseshoe. Specifically, we first use the transversal structure of stable and unstable manifolds to make a linear transformation and then introduce a nonlinear Poincaré map $P$ by considering the truncated flow near the degenerate saddle; based on this Poincaré map $P$ , we define an invertible map $f$ , which is a composite function; by carefully checking the satisfiability of the Conley–Moser conditions for $f$ we finally prove that $f$ is a Smale horseshoe map, which implies that our restricted four-body problem has the chaotic dynamics of the Smale horseshoe type.     

MATLAB-Based Simulation of Buoyancy-Driven Underwater Glider Motion

The mass configuration of the buoyancy-driven underwater glider is decomposed and defined. The coupling between the glider body and its internal masses is addressed using the energy law. A glider motion model is established, and the corresponding simulation program is derived using MATLAB. The characteristics of the glider motion are explored using this program. The simulation results show that the basic characteristic of a buoyancy-driven underwater glider is the periodic alternation of downward and upward motions. The glider＇s spiral motion can be applied to missions in restricted regions. The glider＇s horizontal velocity, gliding depth and its motion radius in spiral motion can be changed to meet different application purposes by using different glider parameter designs. The simulation also shows that the model is appropriate and the program has strong simulation functions.     

2007年冬季大连市区气溶胶垂直剖面特征

选用2007年1月8—30日期间8个无云天的激光雷达资料进行分析。基于Fernald方法反演得到气溶胶消光系数廓线,结合无线电探空资料分析了边界层内气溶胶时空分布,并将反演的激光雷达最低观测高度处(180 m)的气溶胶消光系数与地面PM10、能见度资料进行对比分析。结果表明：冬季大连市区气溶胶主要分布在2 km以下区域,早晨和夜间在0.5 km以下区域经常存在一个气溶胶层;气溶胶消光系数廓线与探空资料较吻合;反演激光雷达最低观测高度处(180 m)的气溶胶消光系数与地面的PM10浓度呈正相关,与能见度呈负相关,相关性较好。