Using an airborne laser scanner for the identification of shallow landslides and susceptibility assessment in an area of ignimbrite overlain by permeable pyroclastics   总被引：3，自引：1，他引：2  

Masahiro?ChigiraEmail author  Fengjun?Duan  Hiroshi?Yagi  Takahiko?Furuya 《Landslides》2004,1(3):203-209

An airborne laser scanner can identify shallow landslides even when they are only several meters in diameter and are hidden by vegetation, if the vegetation is coniferous or deciduous trees in a season with fewer leaves. We used an airborne laser scanner to survey an area of the 1998 Fukushima disaster, during which more than 1,000 shallow landslides occurred on slopes of vapor-phase crystallized ignimbrite overlain by permeable pyroclastics. We identified landslides that have occurred at the 1998 event and also previous landslides that were hidden by vegetation. The landslide density of slopes steeper than 20° was 117 landslides/km² before the 1998 disaster. This event increased the density by 233 landslides/km² indicating that this area is highly susceptible to shallow landsliding.  相似文献   

一个海气耦合环流模式中的ENSO循环特征及控制机理     

赵珊珊  杨修群 《气象科学》2000,21(3):389-399

本文利用中科院大气所两层全球大气环流模式和十四层热带太平洋模式的耦合环流模式１００年积分中的后３０年的月平均输出资料,通过分析海表面温度、上层海洋热容量和海表面高度异常的年际变化,揭示了模式ＥＮＳＯ循环（包括其产生、发展、成熟和消亡过程）的特征及其控制机理。结果表明,控制本文耦合环流模式中ＥＮＳＯ循环的机理是“时滞振子”模态,这和由中间复杂程度耦合模式得到的ＥＮＳＯ控制机理是一致的。反映了“时滞振  相似文献   

DISCOVERY OF ORGANIC MOLECULES IN DEEP-SEA IRON COSMIC DUST     

彭汉昌  徐培苍 《中国海洋湖沼学报》1995,13(1):9-12

A great quartity of cosmic dust(spherules) was found in deep-sea sediments during May to July,1983manganese nodule investigations by the R/V“XIANGYANGHONG 16”in the area 7°-11°N,167°-178°Win the Pacific.Comprehensive study of the cosmic dust and determination with Laser Raman MolecularMicroprobe(LRMM) of the molecules in it showed that besides Fe-Fe,Fe~(3+)-O,Fe-Ni,Al-O,Fe-Obr-Si and Si-Onb,it also contained the organic molecules C-H-O and C-H-S-O,various no fixed form molecules of C,CH_2,CH_3 and volatile molecules CO_2,H_2O,OH~- and H_2S,etc…The study result has very important applications for exploring the origin of interplanetary dust parti-cles and life material.  相似文献   

热带太平洋ENSO事件和印度洋的DIPOLE事件   总被引：12，自引：2，他引：12       下载免费PDF全文

巢纪平  巢清尘  刘琳 《气象学报》2005,63(5):594-602

在热带太平洋和印度洋的次表层构造了一个气候上的海温距平极值曲面(接近由20℃定义的温跃层曲面),分析了1960~2000年海温距平在这一曲面上演变的统计行为,指出,在这个曲面上分析海温距平的演变要比分析海表温度距平的演变规律更清楚,例如热带太平洋的ENSO事件,海温距平信号在赤道和南北10°左右的纬带附近呈逆时针方向传播,在传播过程中其强度产生变化甚至变号;在热带印度洋的Dipole若在最大海温距平曲面上来分析,则西、东印度洋的海温距平在统计上呈负相关(真正物理意义下的Dipole),而不像用海表温度距平分析那样只在西、东温度距平梯度上呈现年际的正、负号变化。进一步的分析表明,ENSO和Dipole的发展,在统计上呈现出时滞的相互关系,一般赤道东太平洋的海温距平变化在前(一个季度左右),联系这两者变化之间的纽带是赤道太平洋和印度洋的一对反相转动的Walker环流的耦合演变。  相似文献   

激光共聚焦扫描显微检测技术在大庆探区储层分析研究中的新进展   总被引：3，自引：0，他引：3  

孙先达  索丽敏张民志王璞珺 《岩石学报》2005,21(5):1479-1488

激光共聚焦扫描显微镜（Laser Confocal Scanning Microscope）分析技术是20世纪80年代末、90年代初兴起的一项新的光学显微测试方法，它具有普通光学显微镜和扫描电子显微镜不具备的很多优点，如样品制备十分简单、分层扫描和三维立体图像重建、清晰分辨有机和无机质等。我们将该技术应用到大庆探区的储层研究中，进行了储层孔隙和微裂缝的三维结构重建，对储层中原油形态进行了详细研究，其中原油形态观察对薄差水淹层的研究有重要意义，研究了裂缝中次生包裹体特征及形成期次，此外，该方法应用于微体古生物化石研究在大庆探区发现了以前本区未见的孢子化石种类。在原油乳化机理研究方面，首次应用共聚焦观察了乳化油的内部结构，通过动态分析可以确定其稳定性，这为乳化油乳化机理研究提供了科学可靠的依据。激光扫描共聚焦显微检测技术在大庆探区储层分析研究中取得了前所未有的效果。  相似文献   

东天山香山镁铁-超镁铁岩中富CH4流体包裹体的特征及其意义   总被引：1，自引：0，他引：1  

潘小菲  刘伟 《岩石学报》2005,21(1):211-218

香山岩体是东天山镁铁-超镁铁杂岩带的一个典型岩体，相带发育。各相带都含有韭闪石质普通角闪石巨晶，后环绕橄榄石和拉长石生长，构成包橄结构和包含结构，表明母岩浆富水。本研究的样品采自于香山岩体中岩体。拉长石和橄榄石中的流体包裹体孤立分布，或成群分布，大小不等，无明显方向性，或成串分布，平行于寄主矿物的颗粒边界和生长晶面。流体包裹体主要为原生，一部分为次生或假次生，是在以角闪石结晶为标志的岩浆流体大量出溶期间捕获的，因而代表了岩浆源区的流体。运用显微激光拉曼光谱仪，在100～4000cm。全波段范围内对拉长石和橄榄石中的50多个流体包裹体的气泡进行了分析。结果表明，流体包裹体的气体成分分为4类：a)富CH4气体；b)富H2O气体；c)H2O CH4混合气体；d)多组分(C2H6 N2 CH4，C2H6 CH4 N2 C4H6)混合气体。因而，香山岩体所携带的流体是一种富CH4等还原性挥发份和富H2O的流体。由于上地幔处于相对氧化状态，上地幔的挥发份以CO2为主。因而，香山岩体的母岩浆和流体应该来自于地幔过渡带或软流圈，这同时也表明新疆北部晚古生代的地幔过渡带或软流圈可能是未被氧化的、含C—H系列流体的圈层。俯冲板片的再循环，为地幔深处的H2O提供了来源。富CH4还原性C—H流体和富H2O流体，为地幔深处的熔融发挥了重要作用，进而产生了新疆北部造山后广泛分布的镁铁一超镁铁岩浆以及铜镍硫化物矿床。  相似文献   

Correction of laser scanning intensity data: Data and model-driven approaches   总被引：7，自引：0，他引：7  

Bernhard Hfle  Norbert Pfeifer 《ISPRS Journal of Photogrammetry and Remote Sensing》2007,62(6):415-433

Most airborne and terrestrial laser scanning systems additionally record the received signal intensity for each measurement. Multiple studies show the potential of this intensity value for a great variety of applications (e.g. strip adjustment, forestry, glaciology), but also state problems if using the original recorded values. Three main factors, a) spherical loss, b) topographic and c) atmospheric effects, influence the backscatter of the emitted laser power, which leads to a noticeably heterogeneous representation of the received power. This paper describes two different methods for correcting the laser scanning intensity data for these known influences resulting in a value proportional to the reflectance of the scanned surface. The first approach – data-driven correction – uses predefined homogeneous areas to empirically estimate the best parameters (least-squares adjustment) for a given global correction function accounting for all range-dependent influences. The second approach – model-driven correction – corrects each intensity independently based on the physical principle of radar systems. The evaluation of both methods, based on homogeneous reflecting areas acquired at different heights in different missions, indicates a clear reduction of intensity variation, to 1/3.5 of the original variation, and offsets between flight strips to 1/10. The presented correction methods establish a great potential for laser scanning intensity to be used for surface classification and multi-temporal analyses.  相似文献   

Coupled equations for transient water flow, heat flow, and deformation in hydrogeological systems     

T. N. Narasimhan 《Journal of Earth System Science》2006,115(2):219-228

  相似文献   

Application of a long-range Terrestrial Laser Scanner to a detailed rockfall study at Vall de Núria (Eastern Pyrenees, Spain)     

A. Abelln  J.M. Vilaplana  J. Martínez 《Engineering Geology》2006,88(3-4):136-148

In this study we show the application of a long-range Terrestrial Laser Scanner (TLS) to a detailed rockfall study in a test zone at Vall de Núria, located in the Eastern Pyrenees. Data acquisition was carried out using TLS-Ilris3D, the new generation of reflector-less laser scanners with a high range, accuracy and velocity of measurements. Eight scans were performed at 3 stations to acquire coordinates of almost 4 million points. The results from the acquired data are a high accuracy Digital Elevation Model (DEM) and the reconstruction of the joint geometry. The former is used for inventory of rockfalls and for more accurate rockfall simulation (trajectories and velocities). The latter allows us to model the geometry and volume of the source area in recent rockfalls. Our findings suggest that TLS technology could be a tool of reference in rockfall studies in the near future.  相似文献   

Zircon Ce4+/Ce3+ ratios and ages for Yulong ore-bearing porphyries in eastern Tibet     

Hua-Ying Liang  Ian H. Campbell  Charlotte Allen  Wei-Dong Sun  Cong-Qiang Liu  Heng-Xiang Yu  Ying-Wen Xie  Yu-Qiang Zhang 《Mineralium Deposita》2006,41(2):152-159

Yulong ore-bearing porphyries, along the northwestern extension of the Red River–Ailao Shan fault system in eastern Tibet, consist of five porphyry deposits, containing a total of more than 8 million tons of copper resources. U–Th–Pb laser inductively coupled plasma mass spectrometry dating of zircon shows that the porphyries were emplaced in Early Tertiary (41.2–36.9 Ma), covering a period of ∼4.3 Ma, with formation ages decreasing systematically from northwest to southeast. The start of porphyry magmatism coincided with the onset of transpressional movement along the Red River–Ailao Shan fault system, implying a close link between these two events. Age sequence in intrusions can be plausibly explained by assuming that a region of melting in the lower northwestern plate moved southeasternward along the Tuoba–Mangkang fault relative to the upper plate. Zircon grains from the Yulong ore-bearing porphyries have higher Ce⁴⁺/Ce³⁺ than those from barren porphyries in the region. This suggests that the ore-bearing porphyries crystallized from a relatively oxidized magma, which has important implications for future ore exploration in the region and other Cu deposits in convergent margin environments in general.  相似文献