晋北区中小地震活动与晋冀蒙交界区6级地震的关系   总被引：1，自引：1，他引：1       下载免费PDF全文

王化宇  殷志刚 《地震工程学报》2005,27(1):80-84

分析了晋北区中小地震(3.0≤ML≤5.0)的活动特征。统计发现,在1989 年山西大同-阳高6.1、1996年内蒙包头6.4和1998年河北张北6.2 级中强地震前1~2 年内晋北地区的中小地震活动年频次有明显的增强-衰减-发震这一特征;震前主震近场区的地震条带活动对主震位置有预示意义,而较远场的地震活动仅反映主震前应力水平的增强。并有震前活动向未来强震区靠近的特征。  相似文献   

内蒙古中西部地区震源参数和场地响应反演   总被引：15，自引：0，他引：15       下载免费PDF全文

高立新  郑斯华  丁风和 《地震工程学报》2005,27(2):109-114

采用Atkinson方法，基于遗传算法，利用呼和浩特数字地震台网7个子台记录的9次质量较高的地震事件资料，计算了内蒙古中西部地区的品质因子Q值和非弹性衰减系数c（f）。在所研究的频率范围内，前者和频率．厂有很好的线形关系：Q（f）=116．8f^1.000后者与频率．厂的变化关系不明显。在此基础上采用Moya方法反演了7个地震台的场地响应和地震的震源参数，并对它们之间的相互关系进行了讨论。结果显示在所研究的频率域内7个基岩台站的场地均不同程度的存在放大作用，其次震源参数间具有较好的线性关系。本文还详细介绍了Atkinson方法和Moya方法的原理和计算步骤。  相似文献   

Spatial damage distribution of August 16,2003,Inner Mongolia,China,M_S=5.9 earth-quake and analysis     

高孟潭  许力生  郭文生  万波  俞言祥 《地震学报(英文版)》2005,18(2)

Introduction The ground motion is generally estimated by attenuation relation in seismic hazard assesment.The attenuation relation is usually the function of earthquake magnitude and distance.Actually the focal mechanism and other source parameters may also have significant impacts on the ground motion,especially in the near-source region.Recent post-earthquake investigations show that the damages have close relation with the closest fault-plane distance.On August16,2003,a MS=5.9earthquake o…  相似文献   

内蒙古中西部地区土壤水分对沙尘暴的贡献   总被引：2，自引：0，他引：2  

李彰俊  李宁  顾卫  吴学宏 《地球科学进展》2005,20(1):24-28

以2001年4月至2002年6月内蒙中部地区逐时观测的土壤水分资料为基础，论证了该区日土壤水分和日平均风速的变化规律，统计分析了日平均风速与土壤水分对沙尘暴的成生综合贡献。得出的主要结论是：①该地区沙尘暴发生时日平均风速的最小值是3．5m／s。如果日平均风速大于8．0m／s，预示着有沙尘暴的发生。②在平均风速大于3.5m／s的条件下，观测样本中18．4％日数发生沙尘暴，而81．6％日数没有发生。说明大风的天气条件不应当被视其为沙尘暴的唯一重要的因子。③在同一地点、同样的风力条件下，在沙尘暴发生时，日平均风速与日平均土壤水分呈明显的反相关变化；而它们的反相关关系不明显时，沙尘暴就很少发生。  相似文献   

Stability and accuracy analysis of the central difference method for real‐time substructure testing     

B. Wu  H. Bao  J. Ou  S. Tian 《地震工程与结构动力学》2005,34(7):705-718

The central difference method (CDM) that is explicit for pseudo‐dynamic testing is also believed to be explicit for real‐time substructure testing (RST). However, to obtain the correct velocity dependent restoring force of the physical substructure being tested, the target velocity is required to be calculated as well as the displacement. The standard CDM provides only explicit target displacement but not explicit target velocity. This paper investigates the required modification of the standard central difference method when applied to RST and analyzes the stability and accuracy of the modified CDM for RST. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Incorporating Spatial Dependence in Predictive Vegetation Models: Residual Interpolation Methods*     

Jennifer Miller 《The Professional geographer》2005,57(2):169-184

Predictive vegetation modeling can be used statistically to relate the distribution of vegetation across a landscape as a function of important environmental variables. Often these models are developed without considering the spatial pattern that is inherent in biogeographical data, resulting from either biotic processes or missing or misspecified environmental variables. Including spatial dependence explicitly in a predictive model can be an efficient way to improve model accuracy with the available data. In this study, model residuals were interpolated and added to model predictions, and the resulting prediction accuracies were assessed. Adding kriged residuals improved model accuracy more often than adding simulated residuals, although some alliances showed no improvement or worse accuracy when residuals were added. In general, the prediction accuracies that were not increased by adding kriged residuals were either rare in the sample or had high nonspatial model accuracy. Regression interpolation methods can be an important addition to current tools used in predictive vegetation models as they allow observations that are predicted well by environmental variables to be left alone, while adjusting over‐ and underpredicted observations based on local factors.  相似文献   

Correcting the Smoothing Effect of Ordinary Kriging Estimates   总被引：2，自引：0，他引：2  

Jorge Kazuo Yamamoto 《Mathematical Geology》2005,37(1):69-94

The smoothing effect of ordinary kriging is a well-known dangerous effect associated with this estimation technique. Consequently kriging estimates do not reproduce both histogram and semivariogram model of sample data. A four-step procedure for correcting the smoothing effect of ordinary kriging estimates is shown to be efficient for the reproduction of histogram and semivariogram without loss of local accuracy. Furthermore, this procedure provides a unique map sharing both local and global accuracies. Ordinary kriging with a proper correction for smoothing effect can be revitalized as a reliable estimation method that allows a better use of the available information.  相似文献   

内蒙古大青山-乌拉山地区孔兹岩系的早期变质地层结构——下地壳近水平顺层滑脱变形的产物   总被引：4，自引：0，他引：4  

徐仲元刘正宏  杨振升 《地层学杂志》2005,29(11):423-432

近年来孔兹岩系作为高级变质岩区一套特征性的变质沉积岩石组合而受到广泛关注，但其变质地层结构及其相关的构造作用和构造样式还不为人所了解。通过对内蒙古大青山一乌拉山地区以孔兹岩系发育为特征的高级变质杂岩的研究发现，区内孔兹岩系自下而上由3个岩石地层单位组成：榴云片麻岩岩组、透辉片麻岩岩组和大理岩岩组，表现出由细碎屑沉积-碎屑沉积和钙质化学沉积的混合物-镁质碳酸盐组成的沉积旋回。这些变质地层不仅遭受到具有近等温降压顺时针P-T演化特征的麻粒岩相变质作用的改造，同时，还遭受到近水平顺层滑脱变形构造、穹-褶构造和近东西向陡倾叶理带这三种构造形式为主的多期变形的改造。由此，这些变质地层在空间上多以不规则条带状、不规则团块状或透镜状形式出露，同时，各地层单位在空间上具有“犬牙交错，参差产出”，“岩层缺失，隔层相触”的特征。研究结果表明，区内孔兹岩系目前的产出状态及“犬牙交错，参差产出”的特征是穹-褶构造尤其是近东西向陡倾叶理带叠加改造的结果，在消除其改造的影响后可以确定，由于近水平顺层滑脱变形改造的结果，这些变质地层发生“岩层缺失，隔层相触”，在空间上表现为以近水平的长轴近东西向的扁豆体堆叠而成的早期变质地层结构，这是高级变质地层所特有的变质地层结构。  相似文献   

Snow model sensitivity analysis to understand spatial and temporal snow dynamics in a high‐elevation catchment          下载免费PDF全文

Michael Engel  Claudia Notarnicola  Stefano Endrizzi  Giacomo Bertoldi 《水文研究》2017,31(23):4151-4168

In this paper, we addressed a sensitivity analysis of the snow module of the GEOtop2.0 model at point and catchment scale in a small high‐elevation catchment in the Eastern Italian Alps (catchment size: 61 km²). Simulated snow depth and snow water equivalent at the point scale were compared with measured data at four locations from 2009 to 2013. At the catchment scale, simulated snow‐covered area (SCA) was compared with binary snow cover maps derived from moderate‐resolution imaging spectroradiometer (MODIS) and Landsat satellite imagery. Sensitivity analyses were used to assess the effect of different model parameterizations on model performance at both scales and the effect of different thresholds of simulated snow depth on the agreement with MODIS data. Our results at point scale indicated that modifying only the “snow correction factor” resulted in substantial improvements of the snow model and effectively compensated inaccurate winter precipitation by enhancing snow accumulation. SCA inaccuracies at catchment scale during accumulation and melt period were affected little by different snow depth thresholds when using calibrated winter precipitation from point scale. However, inaccuracies were strongly controlled by topographic characteristics and model parameterizations driving snow albedo (“snow ageing coefficient” and “extinction of snow albedo”) during accumulation and melt period. Although highest accuracies (overall accuracy = 1 in 86% of the catchment area) were observed during winter, lower accuracies (overall accuracy < 0.7) occurred during the early accumulation and melt period (in 29% and 23%, respectively), mostly present in areas with grassland and forest, slopes of 20–40°, areas exposed NW or areas with a topographic roughness index of ?0.25 to 0 m. These findings may give recommendations for defining more effective model parameterization strategies and guide future work, in which simulated and MODIS SCA may be combined to generate improved products for SCA monitoring in Alpine catchments.  相似文献   

基于决策树分类的大屯矿区地物信息提取及矿区污染分析     

于海若  燕琴  董春  战丽丽 《测绘与空间地理信息》2016,(4):67-69,72

本文在对国内外遥感图像分类方法充分研究分析的基础上,选择决策树分类法对大屯矿区的Landsat 8遥感图像进行分类研究。选取样本提取并分析研究区典型地类光谱特征曲线,依据光谱曲线特征和归一化植被指数建立了土地利用分类决策树模型,通过反复试验和修正,筛选出适宜大屯矿区地物分类的决策树最优阈值,对研究区进行分类和精度评价,最后通过分类结果对研究区的水体污染状况进行简要分析。  相似文献