中国—欧洲共同体地震科学合作项目“北京西北延庆—怀来盆地地震学研究”进展

为探索强烈地震的前兆，在欧洲共同体的支持下，中国和英国的地震学家共同在北京西北的延庆—怀来盆地建立了一个数字地震台网．延庆—怀来数字地震台网由５个野外台和一个中心台构成。研究工作的重点是探索强烈地震前地震横波分裂现象中的参数变化．１９９５年４月３０日台网建成并投入运作．１９９５年７月下旬．怀来地区发生ＭＬ＝４．０地震及其余震，延庆—怀来数字地震台网很好地记录了这一地震序列。初步的分析表明．这一地震序列表明了怀来县城以南６—８ｋｍ处，怀来盆地南缘下部的断层活动，它与怀来地区地表有明显出露的主要断裂没有明显的直接联系。     

Automated mapping of land components from digital elevation data

An algorithm for automating the mapping of land components from digital elevation data is described. Land components are areas of relatively uniform slope and aspect and often correspond with ridge crests, shoulders, head slopes, back slopes or foot slopes. Aspect regions, which generally span from stream to ridge, are first identified by generalizing an aspect map derived from digital elevation data. The aspect regions are then split successively into land components by grouping pixels above or below an automatically determined contour of elevation or ‘distance from stream’. The contour approximates a slope break. The land components mapped in this way give a complete polygonization of a hilly landscape and are a reasonable approximation of manually mapped land components.     

化探数据K－L变换图像分析及其在金矿成矿规律研究中的应用

Ｋ－Ｌ变换是遥感数字图像处理中常用的方法之一。文中用Ｋ－Ｌ变换图像分析的方法对冀北区域化探数据进行再分析，提取出张家口—赤城金矿化集中区金矿成矿期次的信息，并用数字图像复合分析的方法探讨了各成矿期在空间上的发育情况。     

广西金牙金矿含金流体的动力学迁移

根据广西金牙及右江三叠纪贫地中的众多微细浸染型金矿床的均位于三叠纪盆地水下碳酸盐台地的边缘且弧形断裂的预顶部位这一事实,作者在金牙金矿物质和成矿流体来源于沉积盆地的基础上,对台地边缘区作沉积构造分析和流体动力学分析,应用流体势理论及数字化模拟技术得出;成矿流体在压力下趋于向台地边缘斜坡且弧形断裂的弧顶部位集中。     

数字地球的时空维实现

在全球变化研究和持续发展战略推动下形成的地理信息科学是数字地球的科学技术基础,而数字地球也为地理信息科学的发展提供了源动力。数字地球将深刻改变人类的政治、经济和科技格局。现在还不能给数字地球一个明确的定义,但可以认为数字地球的核心是一个分布式、多尺度、多维的地理信息系统。TGIS研究是实现数字地球的关键技术之一。目前可以本着综合型和分解型两种思路对TGIS进行平行探索。     

Assessing global Sentinel-2 coverage dynamics and data availability for operational Earth observation (EO) applications using the EO-Compass

ABSTRACT

Sentinel-2 scenes are increasingly being used in operational Earth observation (EO) applications at regional, continental and global scales, in near-real time applications, and with multi-temporal approaches. On a broader scale, they are therefore one of the most important facilitators of the Digital Earth. However, the data quality and availability are not spatially and temporally homogeneous due to effects related to cloudiness, the position on the Earth or the acquisition plan. The spatio-temporal inhomogeneity of the underlying data may therefore affect any big remote sensing analysis and is important to consider. This study presents an assessment of the metadata for all accessible Sentinel-2 Level-1C scenes acquired in 2017, enabling the spatio-temporal coverage and availability to be quantified, including scene availability and cloudiness. Spatial exploratory analysis of the global, multi-temporal metadata also reveals that higher acquisition frequencies do not necessarily yield more cloud-free scenes and exposes metadata quality issues, e.g. systematically incorrect cloud cover estimation in high, non-vegetated altitudes. The continuously updated datasets and analysis results are accessible as a Web application called EO-Compass. It contributes to a better understanding and selection of Sentinel-2 scenes, and improves the planning and interpretation of remote sensing analyses.     

地震前兆信息系统的信息分解与浓缩

本文运用数值分类学中的因子分析方法,试图从多种前兆观测时序集中浓缩与分解出与地震孕育发生有关的成因信息。并用诸如“地震过程”这样一些概念来代表和归纳一组互相紧密相关的前兆现象和特征。这是与孕震系统在统一区域应力场作用下的整体性行为及子系统之间的协同关联运动的事实在思路上是相一致的。若干震例的研究结果表明,数值分类学是我们实现多台站、多手段,时、空动态综合预报思路的一种较好的方法。     

Extraction of sedimentological information via computer-based image analyses of gray shales in carboniferous coal-bearing sections of Indiana and Kansas, USA

Fine-scale fabric within shales can be used to interpret environments of deposition. In particular, systematic variations in lamina thicknesses can be used to suggest the presence or absence of specific sedimentological controlling factors, such as tides. Herein, shale fabric is analyzed from Carboniferous coal-bearing and siliciclastic-rich formations in Indiana and Kansas. The shales exhibit well developed, normally graded lamina. Sediment grain sizes range from silt and sand at the base of the lamina up to silt and clay at the top. Computer-based optical scanning of prepared shale samples was undertaken so that the lamina thicknesses could be extracted automatically and then used for thickness-series analysis. The sands and silts tend to be very light in color because they consist of well sorted, quartz-rich sands. Conversely, the silt and clay that cap the laminae tend to be dark because of the small grain size; such fine-grained layers also contain large amounts of macerated and coalified plant material. Grain size and sedimentological differences within the laminae can be detected by optical properties and this facilitates automated image processing. Extraction of laminae thicknesses and harmonic analyses of laminae-thickness series can then be used to test the reasonability of specific environmental processes, such as tidal forcing, that were operative during the formation of these shales.     

长江三峡工程构造应力场数值模拟

本文分别进行了长江三峡工程区域1/100万现今构造应力场有限元数值模拟和长江三峡工程库首区1/50万燕山期、新构造期和现今构造应力场演化规律模拟和分析。区域模拟结果表明:坝区不存在发生大于5级地震的构造应力场背景,库首区模拟结果表明:坝区不存在发生大于3级地震的构造应力场背景。