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1.
A total of 163 free-field acceleration time histories recorded at epicentral distances of up to 200 km from 32 earthquakes with moment magnitudes ranging from M w 4.9 to 7.4 have been used to investigate the predictive capabilities of the local, regional, and next generation attenuation (NGA) ground-motion prediction equations and determine their applicability for northern Iran. Two different statistical approaches, namely the likelihood method (LH) of Scherbaum et al. (Bull Seismol Soc Am 94:341–348, 2004) and the average log-likelihood method (LLH) of Scherbaum et al. (Bull Seismol Soc Am 99:3234–3247, 2009), have been applied for evaluation of these models. The best-fitting models (considering both the LH and LLH results) over the entire frequency range of interest are those of Ghasemi et al. (Seismol 13:499–515, 2009a) and Soghrat et al. (Geophys J Int 188:645–679, 2012) among the local models, Abrahamson and Silva (Earthq Spectra 24:67–97, 2008) and Chiou and Youngs (Earthq Spectra 24:173–215, 2008) among the NGA models, and finally Akkar and Bommer (Seism Res Lett 81:195–206, 2010) among the regional models.  相似文献   

2.
Three-dimensional, elastic and elasto-plastic finite element (FE) programs have permitted calculation of the displacements and the factor of safety (FOS) for the excavation for a tower, 132.70 m high (above foundation) on the island of Tenerife. The tower is supported by a 2 m thick reinforced concrete slab on jointed, vesicular and weathered basalt and scoria. The installation of rod extensometers at different depths below the slab has permitted comparison between measured and calculated displacements and the estimation of in situ deformation modulus. The moduli deduced from the simple empirical equations proposed by Hoek et al. (In: NARMS-TAC, 2002) and Gokceoglu et al. (Int J Rock Mech Min Sci 40:701–710, 2003) as a function of GSI, and Nicholson and Bieniawski (Int J Min Geol Eng 8:181–202, 1990) as a function of RMR, provide an acceptable fit with the measured settlements in this type of rock. Good correlation is also obtained with the empirical equation presented by Verman et al. (Rock Mech Rock Eng 30(3):121–127, 1997) that incorporates the influence of confining stress in the deformation modulus. The FOS obtained from different correlations with geomechanical classifications is within a relatively narrow range. These results increase our confidence in the use of classification schemes to estimate the deformation and stability in jointed rock.  相似文献   

3.
A Digital Elevation Model issued from the SRTM mission was assessed on a study area located in a dense equatorial forest setting in French Guiana. The SRTM DEM defined on a 90-m grid was compared to three check sources: (1) airborne laser altimeter data, (2) an accurate heliborne DEM, and (3) spot heights. The paper also includes a comparison with a radargrammetric RADARSAT DEM. The results show that the accuracy of the SRTM DEM is about 10 m (standard deviation of errors). For a given slope aspect, the absolute value and the standard deviation of elevation errors increase almost linearly with the slope value. The slope aspect has a major influence on the sign of the elevation error: elevations are underestimated for slope facing SRTM signal (foreslopes, northwest), and conversely in the opposite direction (backslopes, southeast). Maximum errors are observed along these two directions. To cite this article: B. Bourgine, N. Baghdadi, C. R. Geoscience 337 (2005).  相似文献   

4.
The successful operation of the TanDEM-X satellite mission is the start of a new era of globally consistent and accurate digital elevation data for planet Earth. In this work available 12 m-resolution intermediate TanDEM-X products (DEM: digital elevation model; HEM: height error map; COV: coverage map; WAM: water indication mask) are evaluated over Tasmania. Elevations from the TanDEM-X intermediate digital elevation model (IDEM) are compared with (a) other global DEMs (30 m-resolution SRTM1 USGS v3 and 30 m-resolution Advanced Spaceborne Thermal Emission Reflectometer (ASTER GDEM2), (b) the local 25 m-resolution DEM made available by Tasmanian environmental authority (DPIPWE), and (c) over 15 000 accurate ground-control-points (GCPs) from the Australian National Gravity Database (ANGD). The comparison with ASTER and SRTM over the area of Tasmania involves over 500 million valid TanDEM-X IDEM elevations. The root-mean-square (RMS) of 8.8 m indicates a reasonable to good agreement of TanDEM-X IDEM and SRTM, while ASTER shows almost twice the disagreement in terms of RMS (~16.5 m). Both, ASTER and SRTM show a (mean) offset of –1.9 m and –2.3 m w.r.t. TanDEM-X IDEM, respectively. By comparisons with GCPs, we find that SRTM and ASTER overestimate the terrain height. The comparison with the AGND GCPs also allows an estimate of the absolute accuracy of the IDEM, which is found to be superior to that of SRTM or ASTER. The RMS error of 6.6 m shows that the IDEM is close to the officially denoted 4 m absolute vertical accuracy considering that the GCPs are not error free. The height error map information layer is found to a suitable first indicator of the (local) accuracy of the IDEM in a relative sense. However, we find that the HEM tends to underestimate observed differences to the GCPs. Terrain-type analyses reveal that the TanDEM-X IDEM is a very consistent elevation database over Tasmania. In conclusion, our study demonstrates that the new TanDEM-X elevation data sets provide improved high-resolution terrain information over Tasmania and beyond.  相似文献   

5.
大别山构造地貌的DEM初步分析   总被引:7,自引:1,他引:6  
以地理信息系统(GIS)为平台,利用航天飞机雷达地形测量(SRTM)数据,构建了大别造山带地区的数字高程模型(DEM),对大别山地区的构造地貌进行了模拟解译分析.研究表明,大别山在造山带走向和垂直走向的方向上都是中间高、两边低,两边地势低的部位发育断陷盆地.SRTM DEM地貌图显示,郯庐等大断裂地貌特征明显,断裂构造严格控制了水系的发育,大别山水系多呈格子状分布,在地貌上主要表现为河流的大角度转弯以及主支流近直角交汇;由于本区地壳沿断裂作差异性升降运动,造成地堑谷、断块山和断陷盆地并存的地貌特点.本文统计分析了坡度与高程之间的相互关系,并提取了夷平面信息.   相似文献   

6.
The liquefaction potential of saturated cohesionless deposits in Guwahati city, Assam, was evaluated. The critical cyclic stress ratio required to cause liquefaction and the cyclic stress ratio induced by an earthquake were obtained using the simplified empirical method developed by Seed and Idriss (J soil Mech Found Eng ASCE 97(SM9):1249–1273, 1971, Ground motions and soil liquefaction during earthquakes. Earthquake Engineering Research Institute, Berkeley, CA, 1982) and Seed et al. (J Geotech Eng ASCE 109(3):458–483, 1983, J Geotech Eng ASCE 111(12):1425–1445, 1985) and the Idriss and Boulanger (2004) method. Critical cyclic stress ratio was based on the empirical relationship between standard penetration resistance and cyclic stress ratio. The liquefaction potential was evaluated by determining factor of safety against liquefaction with depth for areas in the city. A soil database from 200 boreholes covering an area of 262 km2 was used for the purpose. A design peak ground acceleration of 0.36 g was used since Guwahati falls in zone V according to the seismic zoning map of India. The results show that 48 sites in Guwahati are vulnerable to liquefaction according to the Seed and Idriss method and 49 sites are vulnerable to liquefaction according to the Idriss and Boulanger method. Results are presented as maps showing zones of levels of risk of liquefaction.  相似文献   

7.
DEM数据源及分辨率对HEC-HMS水文模拟的影响   总被引:2,自引:0,他引:2       下载免费PDF全文
DEM数据源及分辨率会影响流域特征参数的提取,进而影响水文模拟结果.将ASTER 30 m DEM、SRTM 90 m DEM及基于ASTER 30 m DEM的40 m、50 m、60 m、70 m、80 m、90 m重采样DEM作为HEC-geoHMS模型输入,提取流域特征,采用HEC-HMS模型,以西笤溪流域为研究区域,分析2011年6月和2011年8—9月的两场降雨径流过程中,DEM数据源和分辨率对水文模拟输出的影响.研究结果表明,两次径流模拟结果与实测数据拟合都较好,模型确定性系数都大于0.82,但是单峰的洪水模拟效果总体更好,基于SRTM 90 m的模型确定性系数比基于ASTER 30 m DEM、重采样90 m DEM的模型确定性系数都大.基于重采样DEM的模型确定性系数变化较大,而且与分辨率的变化呈非线性关系.在HEC-HMS的模拟中,基于ASTER 30 m DEM和基于SRTM 90 m DEM的模拟输出结果相对误差相差3%~5%,基于SRTM 90 m DEM和基于重采样90 m DEM的模拟输出结果相对误差相差2%~4%,基于重采样DEM的模拟输出结果相对误差相差最大达到了11%.  相似文献   

8.
高亚洲冰川区SRTM C-波段DEM数据透射深度研究   总被引:1,自引:0,他引:1  
SRTM数据是研究冰量变化的重要数据之一。基于SRTM C-波段和X-波段的高程数据,对高亚洲不同冰川区SRTM C-波段数据的透射深度进行了研究。结果表明:高亚洲地区SRTMC透射深度的空间分布特征存在较大差异,其中藏色岗日地区的透射深度最大为(5.3±2.1) m,中天山和念青唐古拉西段地区的透射深度最小仅为(0.8±0.6) m。透射深度整体空间分布呈由高亚洲边缘地区向青藏高原内陆先减小后增大,到羌塘高原地区SRTMC的透射深度最大的趋势。气温和降水量的空间差异共同作用是导致SRTMC透射深度呈上述分布状况的主要因素。此外,SRTM X-波段数据的覆盖状况和冰川样本数量的选择会导致不同研究估算出的SRTMC透射深度存在不确定性。  相似文献   

9.
Digital elevation model (DEM) is one of the input data derived from different satellite sensors for hydrologic and hydraulic modelings. Two prime questions could be answered before using these DEMs. First, the acceptability of datasets for our use and second appropriate resolution of the dataset. Three widely used DEMs SRTM 30m, ASTER 30m and SRTM 90m are analyzed to evaluate their suitability to delineate river network and basin boundary area. The hydrology tool of spatial analyst extension inbuilt in ArcGIS 10.2 (which uses the D8 method for calculation of flow direction) has been used for the delineation of both river networks and basin boundary. The assessment of river network alignment and boundary delineation is carried out in the seven sub-catchments of Gandak river basin having different morphological characteristics. The automatically delineated boundary area for all the three DEMs reflects a significant difference when compared with the digitized basin area from the Ganga flood control commission (GFCC) map. The maximum boundary area delineation error is 39137.20 km2 forASTER 30m, and minimum delineation error of 13239.28 km2 for SRTM 90m. In the stream network, delineation accuracy is good for SRTM 90m while, except Gandak trunk, ASTER 30m DEM shows better delineation accuracy indicated by mean absolute error (MAE) and standard deviation (SD).  相似文献   

10.
1:25万常德市幅自西向东跨武陵隆起和江汉—洞庭盆地,具复杂的第四纪隆-凹构造格局。以详细地表调查和大量第四系钻孔资料为基础,以第四纪构造活动、沉积作用以及现今地势高低和地貌形态特征为主要依据,对1∶25万常德市幅进行了构造-沉积地貌类型的划分与编图。构造-沉积地貌类型是以第四纪地质作用为依据对传统地貌类型和地貌单元所作的分解和细化。研究区共厘定出抬升剥蚀中低山(Ⅰ)、抬升剥蚀丘陵(Ⅱ)、沉积-抬蚀丘陵(Ⅲ)、沉积-抬蚀岗状平原(Ⅳ)、残坡积岗状平原(Ⅴ)、孤山(Ⅵ)、沉降沉积-抬蚀岗状平原(Ⅶ)、沉降沉积-抬升波状平原(Ⅷ)、稳定沉积低平原(Ⅸ)、沉降沉积低平原(Ⅹ)等10种构造-沉积地貌类型。详细的解析表明,不同构造-沉积地貌类型的地表高程、第四纪地壳升降特征、风化剥蚀和沉积作用等各具特征。构造-沉积地貌类型的划分及其地貌图的编制,不仅反映出地表地理环境暨地貌特征,同时提供了直观表达不同地区第四纪地层、构造特征及其反映的地质与环境演化过程的有效途径,有助于促进和深化江汉-洞庭盆地第四纪地质与环境研究。  相似文献   

11.
航天飞机雷达地形测绘(shuttle radar topography mission, SRTM)和先进星载热发射和反射辐射成像仪全球数字高程模型(advanced spaceborne thermal emission and reflection radiometer global digital elevation model, ASTER GDEM)提供了全球覆盖面积最广的数字高程模型(digital elevation model, DEM)数据, 但其高程精度还未得到充分验证, 传统地面测量方法很难适用于验证大面积范围的DEM精度.以冰、云和陆地高程卫星/地学激光测高系统(ICESat/GLAS)高程数据为参考, 综合利用地理信息系统(geographic information system, GIS)空间分析、三维可视化与统计分析方法, 对中国典型低海拔沿海平原地区和高海拔山地的两种DEM数据高程精度进行了对比分析.结果表明, 高程值小于20m的低海拔地区, SRTM高程精度达到2.39m, ASTER GDEM的精度达到4.83m, 均远远高于这两种数据的标称精度; 而在西南山地, 这两种DEM的精度大约为20m, 与标称精度相当.最后, 建立了ICESat/GLAS与SRTM和ASTER GDEM的一元线性回归模型, 该模型具有较高的拟合度和显著线性关系, 可用于改善这两种DEM的高程精度.   相似文献   

12.
D. K. Yoon 《Natural Hazards》2012,63(2):823-843
The purpose of this study is to examine and compare the methodologies being developed in assessing social vulnerability to natural disasters. Existing vulnerability literature shows that two methods have been used in developing social vulnerability indexes: (1) a deductive approach based on a theoretical understanding of relationships and (2) an inductive approach based on statistical relationships (Adger et al. in New indicators of vulnerability and adaptive capacity. Tyndall Centre for Climate Change Research, Norwich, 2004). Two techniques were also utilized in aggregating social vulnerability indicators: (1) a deductive approach using standardization techniques such as z scores or linear scaling (Wu et al. in Clim Res 22:255?C270, 2002; Chakraborty et al. in Nat Hazards Rev 6(1):23?C33, 2005) and (2) an inductive approach using data-reduction techniques such as factor analysis (Clark et al. in Mitig Adapt Strateg Glob Change 3(1):59?C82, 1998; Cutter et al. Soc Sci Quart 84(2):242?C261, 2003). This study empirically compares deductive and inductive index development and indicator aggregation methods in assessing social vulnerability to natural disasters in the Gulf of Mexico and Atlantic coastal areas. The aggregated social vulnerability index is used to examine a relationship with disaster losses in the Gulf of Mexico and Atlantic coastal areas. The results show that coastal counties with more vulnerability in terms of social achieved status are positively associated with disaster damages, while variations in the development of the index using deductive and inductive measurement approaches produce different outcomes.  相似文献   

13.
Tianjin coastal plain is flat and its landform is not easy to be divided. The grain size of the sediments is fine, with poor remote sensing interpretation accuracy and field identification, which leads to weak geological map expression effect by the traditional geological survey method. Digital Elevation Model (DEM) is a digital representation of the topographic surface and it has 3D visual information that cannot be expressed by the general topographic map, which can truly reflect the features of the landform. The authors divided the geomorphic units of shallow sediments during the geological mapping process of Tianjin coastal plain based on DEM and the geological survey of the route, the construction of the shallow groove drilling and the sample testing. The shallow sediments can be divided into three sedimentary systems: fluvial sedimentary system, transgression sedimentary systm and deltaic sedimentary system. The fluvial sedimentary system includes several genetic types of point bar, oxbow lake, crevasse splay, natural levee, flood basin and lake marsh. And the transgression sedimentary system can be divided into beach ridge, overland fan, high tide flat, residual lagoon, while the deltaic sedimentary system includes the delta front. DEM can fully make up for the shortage of remote sensing images after the comparative analysis with the results of remote sensing interpretation of different types. Besides, DEM can also be used for the detailed genetic classification of the shallow sediments and improve the cognition about shallow geological process, which will guide the field mapping. The application of high-precision DEM data to the geological mapping on the covered areas of quaternary system can greatly improve the mapping accuracy and efficiency, and provide basic geological support for urban ecological security, territorial space planning and industrial structure layout.  相似文献   

14.
天津市滨海平原地区地势平坦,地貌类型不易划分,沉积物粒度较细,遥感解译精度及实地可识别性差,按照传统的地质调查方法开展填图,图面表达效果不佳。数字高程模型(Digital Elevation Model, DEM)是地形的数字化表达,具有一般地形图无法表达的三维可视化信息,能够真实反映地形地貌特征。在开展天津滨海平原地质填图过程中,通过建立研究区DEM,并结合路线地质调查、槽型浅钻施工、样品测试分析,进行了地貌单元划分,将浅地表沉积物划分为河流、海侵和三角洲3个沉积体系: 河流沉积体系包含边滩(曲流砂坝)、充填河槽(牛轭湖)、决口扇、天然堤、洪泛盆地和湖沼沉积微相; 海侵沉积体系包含海滩脊、越岸扇、高潮坪和残留潟湖沉积微相; 三角洲沉积体系主要为三角洲前缘沉积。通过与不同类型遥感解译结果进行对比分析可知,DEM可充分弥补遥感影像的不足,对浅地表沉积物进行详细的成因类型划分,提升对浅地表地质作用过程的认知程度,较好地指导野外地质填图。将高精度DEM数据应用于第四系覆盖区地质填图,可以大大提高填图精度及效率,为城市生态安全保障、国土空间规划、产业结构布局等提供基础地质依据。  相似文献   

15.
In this paper, we propose a semiautomatic method for landscape analysis of biosphere reserve Eastern Carpathians with both spectral and morphometric constituents. The Shuttle Radar Topography Mission (SRTM) has provided digital elevation models for approximately 80 % of the earth’s land surface. SRTM data are used to calculate first derivatives (slope) and second derivatives of elevation (such as minimum curvature, maximum curvatures, and cross-sectional curvature) by fitting a bivariate quadratic surface with a window size of 9 by 9. Together with multispectral remote sensing data like Landsat 7 ETM+ with 28.5 m raster elements, these data provide comprehensive information for the analysis of the landscape in the study area. Unsupervised neural network algorithm—self-organizing map—divided all input vectors into inclusive and exhaustive classes on the basis of similarity between attribute vectors. An optimal self-organizing map with 21 classes using 1,000 iterations and a final neighborhood radius of 0.05 provided a low average quantization error of 0.3394 and was used for further analysis. Morphometric analysis, spectral signature analysis, and feature space analysis are used to assign semantic meaning to the classes as landscape elements according to form, cover, and slope, e.g., deciduous forest on ridge (convex landform) with steep slopes. The results revealed the efficiency of self-organizing map to integrate SRTM and Landsat data for landscape classification. This makes it possible to develop an alternative method for fast assessment and comparison of landscapes over large areas. This procedure is reproducible for the same applications with consistent results.  相似文献   

16.
In this paper, we study solving iteratively the coupling of flow and mechanics. We demonstrate the stability and convergence of two widely used schemes: the undrained split method and the fixed stress split method. To our knowledge, this is the first time that such results have been rigorously obtained and published in the scientific literature. In addition, we propose a new stress split method, with faster convergence rate than known schemes. These results are specially important today due to the interest in hydraulic fracturing (Dean and Schmidt SPE J. 14:707–714, 2009; Ji et al. SPE J. 14:423–430, 2009; Samier and De Gennaro 2007; Settari and Maurits SPE J. 3:219–226, 1998), in oil and gas shale reservoirs.  相似文献   

17.
孙杰  刘静  仲振维 《地质通报》2009,28(6):726-737
河流地貌和侵蚀是构造地貌研究的核心内容。90m分辨率的SRTM3数字高程模型被广泛运用于构造地貌学的研究,但数据空白区是其在河流地貌定量研究中的瓶颈。对SRTM3数据与中国1:25万DEM数据的对比分析表明,1:25万DEM数据在生成数字河网和河流纵剖面方面不如SRTM3数据,尤其是其在平原区数字河网提取中易发生错误,但在高山峡谷地区数据质量较好,而这正是SRTM3数据空洞的主要区域。对比国内外各种SRTM空洞填补方法发现,相对于算法的改进,高精度数据的参与是填充SRTM3数据空洞的关键。因此,利用SRTM3与1:25万DEM数据的互补性,对SRTM3进行数据优化,是现阶段青藏高原河流地貌定量研究的基础。详细介绍了SRTM3空洞充填的步骤,具有实际参考价值。  相似文献   

18.
A digital terrain model and a 3D fly-through model of the Nigde province in central Anatolia, Turkey were generated and quantitatively analyzed employing the shuttle radar topographic mission (SRTM) digital elevation model (DEM). Besides, stream drainage patterns, lineaments and structural–geological features were extracted and analyzed. In the process of analyzing and interpreting the DEM for landforms, criteria such as color and color tones (attributes of heights), topography (shaded DEM and 3D fly-through model) and stream drainage patterns were employed to acquire geo-information about the land, such as hydrologic, geomorphologic, topographic and tectonic structures. In this study, the SRTM DEM data of the study region were experimentally used for both DEM classification and quantitative analysis of the digital terrain model. The results of the DEM classification are: (1) low plain including the plains of Bor and Altunhisar (20.7%); (2) high plain including the Misli (Konakli) plain (28.8%); (3) plateau plain including the Melendiz (Ciftlik) plateau plain (1.0%); (4) mountain including the Nigde massif (33.3%); and (5) high mountain (16.2%). High mountain areas include a caldera complex of Mt Melendiz, Mt Hasan and Mt Pozanti apart from the Ala mountains called Aladaglar and the Bolkar mountains called Bolkarlar in the study region (7,312 km2). Analysis of both the stream drainage patterns and the lineaments revealed that the Nigde province has a valley zone called Karasu valley zone (KVZ) or Nigde valley zone (NVZ), where settlements and agricultural plains, particularly the Bor plain in addition to settlements of the Bor town and the central city of Nigde have the most flooding risk when a heavy raining occurs. The study revealed that the NVZ diagonally divides the study region roughly into two equal parts, heading from northeast to southwest. According to the map created in this study, the right side of the NVZ has more mountainous area, where the Aladaglar is a wildlife national park consisting of many species of fauna and flora whereas the left side of the NVZ has more agricultural plain, with exception of a caldera complex of Mt Melendiz and volcanic Mt Hasan. The south of the study region includes the Bolkarlar. In addition, the Ecemis fault zone (EFZ) lying along the Ecemis rivulet, running from north to south at the west side of the Aladaglar, forms the most important and sensitive location in the region in terms of the tectonics.  相似文献   

19.
河流地貌和侵蚀是构造地貌研究的核心内容。90m分辨率的SRTM3数字高程模 型被广泛运用于构造地貌学的研究,但数据空白区是其在河流地貌定量研究中的 瓶颈。对SRTM3数据与中国1∶25万DEM数据的对比分析表明,1∶25万DEM数据在 生成数字河网和河流纵剖面方面不如SRTM3数据,尤其是其在平原区数字河网提 取中易发生错误,但在高山峡谷地区数据质量较好,而这正是SRTM3数据空洞的主 要区域。对比国内外各种SRTM空洞填补方法发现,相对于算法的改进,高精度数 据的参与是填充SRTM3数据空洞的关键。因此,利用SRTM3与1∶25万DEM数据的互 补性,对SRTM3进行数据优化,是现阶段青藏高原河流地貌定量研究的基础。详细 介绍了SRTM3空洞充填的步骤,具有实际参考价值。  相似文献   

20.
This paper describes a boundary element code development on coupled thermal–mechanical processes of rock fracture propagation. The code development was based on the fracture mechanics code FRACOD that has previously been developed by Shen and Stephansson (Int J Eng Fracture Mech 47:177–189, 1993) and FRACOM (A fracture propagation code—FRACOD, User’s manual. FRACOM Ltd. 2002) and simulates complex fracture propagation in rocks governed by both tensile and shear mechanisms. For the coupled thermal-fracturing analysis, an indirect boundary element method, namely the fictitious heat source method, was implemented in FRACOD to simulate the temperature change and thermal stresses in rocks. This indirect method is particularly suitable for the thermal-fracturing coupling in FRACOD where the displacement discontinuity method is used for mechanical simulation. The coupled code was also extended to simulate multiple region problems in which rock mass, concrete linings and insulation layers with different thermal and mechanical properties were present. Both verification and application cases were presented where a point heat source in a 2D infinite medium and a pilot LNG underground cavern were solved and studied using the coupled code. Good agreement was observed between the simulation results, analytical solutions and in situ measurements which validates an applicability of the developed coupled code.  相似文献   

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