Crustal structure of the continental margin of Korea in the East Sea (Japan Sea) from deep seismic sounding data: evidence for rifting affected by the hotter than normal mantle   总被引：1，自引：0，他引：1  

Han-Joon Kim  Hyeong-Tae Jou  Hyun-Moo Cho  Harmen Bijwaard  Takeshi Sato  Jong-Kuk Hong  Hai-Soo Yoo  Chang-Eob Baag 《Tectonophysics》2003,364(1-2):25-42

Despite the various opening models of the southwestern part of the East Sea (Japan Sea) between the Korean Peninsula and the Japan Arc, the continental margin of the Korean Peninsula remains unknown in crustal structure. As a result, continental rifting and subsequent seafloor spreading processes to explain the opening of the East Sea have not been adequately addressed. We investigated crustal and sedimentary velocity structures across the Korean margin into the adjacent Ulleung Basin from multichannel seismic (MCS) reflection and ocean bottom seismometer (OBS) data. The Ulleung Basin shows crustal velocity structure typical of oceanic although its crustal thickness of about 10 km is greater than normal. The continental margin documents rapid transition from continental to oceanic crust, exhibiting a remarkable decrease in crustal thickness accompanied by shallowing of Moho over a distance of about 50 km. The crustal model of the margin is characterized by a high-velocity (up to 7.4 km/s) lower crustal (HVLC) layer that is thicker than 10 km under the slope base and pinches out seawards. The HVLC layer is interpreted as magmatic underplating emplaced during continental rifting in response to high upper mantle temperature. The acoustic basement of the slope base shows an igneous stratigraphy developed by massive volcanic eruption. These features suggest that the evolution of the Korean margin can be explained by the processes occurring at volcanic rifted margins. Global earthquake tomography supports our interpretation by defining the abnormally hot upper mantle across the Korean margin and in the Ulleung Basin.  相似文献   

软粘土层上的油罐差异沉降     

徐光明  王铁儒  易进栋 《岩土力学》2003,(Z2)

根据某一大型油罐软基加固处理工程方案设计和优选需要,按照离心模型相似律,开展了三组模型试验,分别模拟了天然地基、土工合成材料袋装碎石垫层和既在填土层中设置袋装碎石垫层又在淤泥质粘土层设置土工合成材料排水板三种情况,以研究这一加固布置形式对减小高压缩性软土层地基上油罐罐底的差异沉降效果反应。模型油罐地基采用原型土重塑制备,现场土工合成材料袋装碎石采用柔性机织玻璃纤维细管塞装粗砂条模拟,并在不停机运转条件下模拟了多次充放水预压加载。试验结果表明,油罐软弱地基经土工合成材料袋装碎石加固后,罐底总沉降值和差异沉降值均明显小于天然地基情形下对应的沉降值,罐底畸变得到显著减小,就本文所述的土质条件、土层厚度和预压荷载强度,地基经加固处理后,油罐罐底畸变减小了近50 %。最后就土工合成材料在加固油罐地基布置形式的合理性进行了初步探讨。  相似文献   

射线透射图像中轻物质自动识别算法的研究     

邵立康  易素君  韩裕生  秦晓燕  丁厚本  沈建华  许小明 《CT理论与应用研究》2003,12(4):1-4

目的：针对射线透射图像中轻物质的自动识别存在的难点问题进行研究。方法：提出了基于轮廓特征和灰度特征的识别算法，结果：详细地阐述了利用识别算法进行识别的过程；结论：给出了识别算法的实验结果。  相似文献   

Theory of satellite ground-track crossovers     

M. C. Kim 《Journal of Geodesy》1997,71(12):749-767

The fundamental geometry of satellite ground tracks and their crossover problem are investigated. For idealized nominal ground tracks, the geometry is governed by a few constant parameters whose variations lead to qualitative changes in the crossover solutions. On the basis that the theory to locate crossovers has not been studied in sufficient detail, such changes are described in regard to the number of crossover solutions in conjunction with their bifurcations. Employing the spinor algebra as a tool for establishing the ground-track crossing condition, numerical methodologies to locate crossovers appearing in general dual-satellite ground-track configurations are also presented. The methodologies are applied to precisely determined orbital ephemerides of the GEOSAT, ERS-1, and TOPEX/POSEIDON altimeter satellites. Received: 19 November 1996 / Accepted: 12 May 1997  相似文献   

SEDIMENTATION STUDY ON PUMPED-STORAGE POWER STATION OF PUSHI RIVER     

WANG Tiefeng Northeast Investigation  Design  Research Institute  China ZHANG Zhi Northeast Investigation  Design  Research Institute  China YI Yue Northeast Investigation. Design  Research Institute  China 《国际泥沙研究》1997,(3)

I.INTRODUCTIONThePtlmped-storagepoll,erprojectofPushiriverisconsistedofupperreservoir,lobal-erreset'oir.watertransmissionSystemandpotvergeneratingsystem.ThelowerreservoirIviththecatchmentbasinareaof1141kmZisthewatersupplierl-c'hichislocatedonthedownstreamofthePushiriverinthesouthernpactofNortheastChina.Theupperreservoirisabout300-400metershigherthanthelowerresen!oirattheleftsideoftheriverwithcatchmentbasinareaof1.12km2.Thecharacteristicsoftheprojectandreservoirareshottviintablel-l.Ino…  相似文献   

Application of an optimum design technique for determining the coefficient of consolidation by using piezocone test data   总被引：4，自引：0，他引：4  

Y.S. Kim  S.R. Lee  Y.T. Kim 《Computers and Geotechnics》1997,21(4):885-293

For normally consolidated clay, several researchers have developed a number of theoretical time factors to determine the coefficient of consolidation from piezocone test results. However, depending on assumptions and analytical techniques, it could vary considerably, even for a specific degree of consolidation. In this paper a method is proposed to determine a consistent coefficient of consolidation by applying the concept of an optimum design technique over all ranges of the degree of consolidation. Initial excess pore pressure distribution is assumed to be capable of being obtained by the successive spherical cavity expansion theory. The dissipation of pore pressure is simulated by means of a two-dimensional linear-uncoupled axi-symmetric consolidation analysis. The minimization of differences between measured and predicted excess pore pressure was carried out by the BFGS unconstrained optimum design algorithm with a one-dimensional golden section search technique. By analyzing numerical examples and in-situ test results, it was found that the adopted optimum design technique gives consistent and convergent results.  相似文献   

Regime interplay: the case of biodiversity and climate change     

Joy A. Kim   《Global Environmental Change》2004,14(4):54

In this paper, the interplay between the biodiversity and climate change regimes is examined in the context of a case study. An understanding of how the regimes interact is crucial to their successful operation, since it provides insight into how policy options might be drawn up to create synergy rather than conflict among the respective regimes’ objectives. Despite the increasing importance of the study of regime interplay, due to its potential influence on regime effectiveness, there is limited understanding of why regimes interact and how their interplay may affect their successful operation, since few empirical studies have been conducted in this area. By analysing the causes of the regime interplay and the potential effects thereof, this paper draws policy implications regarding how the interacting regimes might be better co-ordinated to create synergy.  相似文献   

Influence of the total atmospheric optical depth and cloud cover on solar irradiance components     

K. O. Ogunjobi  Y. J. Kim  Z. He   《Atmospheric Research》2004,70(3-4):209-227

Broadband solar irradiance data obtained in the spectral range 400–940 nm at Kwangju, South Korea from 1999–2000 have been analyzed to investigate the effects of cloud cover and atmospheric optical depth on solar radiation components. Results from measurements indicate that the percentage of direct and diffuse horizontal components of solar irradiance depend largely on total optical depth (TOD) and cloud cover. During summer and spring, the percentages of diffuse solar irradiance relative to the global irradiance were 5.0% and 4.9% as compared to 2.2% and 3.0% during winter and autumn. The diffuse solar irradiance is higher than the direct in spring and summer by 24.2%, and 40.6%, respectively, which may largely be attributed to the attenuation (scattering) of radiation by heavy dust pollution and large cloud amount. In cloud-free conditions with cloud cover ≤2/10, the fraction of the direct and diffuse components were 66.0% and 34.0%, respectively, with a mean daily global irradiance value of 7.92±2.91 MJ m⁻² day⁻¹. However, under cloudy conditions (with cloud cover ≥8/10), the diffuse and direct fractions were 97.9% and 2.2% of the global component, respectively. The annual mean TOD under cloudless conditions (cloud cover≤2/10) yields 0.74±0.33 and increased to as much as 3.15±0.67 under cloudy conditions with cloud amount ≥8/10. An empirical formula is derived for estimating the diffuse and direct components of horizontal solar irradiance by considering the total atmospheric optical depth (TOD). Results from statistical models are shown for the estimation of solar irradiance components as a function of TOD with sufficient accuracy as indicated by low standard error for each solar zenith angle (SZA).  相似文献   

Similarities between strike-slip faults at different scales and a simple age determining method for active faults   总被引：1，自引：0，他引：1  

Young-Seog Kim  David J. Sanderson 《Island Arc》2004,13(1):128-143

Abstract Several differently scaled strike‐slip faults were examined. The faults shared many geometric features, such as secondary fractures and linkage structures (damage zones). Differences in fault style were not related to specific scale ranges. However, it was recognized that differences in style may occur in different tectonic settings (e.g. dilational/contractional relays or wall/linkage/tip zones), different locations along the master fault or different fault evolution stages. Fractal dimensions were compared for two faults (Gozo and San Andreas), which supports the idea of self‐similarity. Fractal dimensions for traces of faults and fractures of damage zones were higher (D ～1.35) than for the main fault traces (D ～1.005) because of increased complexity due to secondary faults and fractures. Based on the statistical analysis of another fault evolution study, single event movements in earthquake faults typically have a maximum earthquake slip : rupture length ratio of approximately 10^?4, although this has only been established for large earthquake faults because of limited data. Most geological faults have a much higher maximum cumulative displacement : fault length ratio; that is, approximately 10^?2 to 10^?1 (e.g. Gozo, ～10^?2; San Andreas, ～10^?1). The final cumulative displacement on a fault is produced by accumulation of slip along ruptures. Hence, using the available information from earthquake faults, such as earthquake slip, recurrence interval, maximum cumulative displacement and fault length, the approximate age of active faults can be estimated. The lower limit of estimated active fault age is expressed with maximum cumulative displacement, earthquake slip and recurrence interval as T ? (d_max /u) · I(M).  相似文献   

On the Effects of Non-planar Geometry for Blind Thrust Faults on Strong Ground Motion     

Hideo Aochi  Kim B. Olsen 《Pure and Applied Geophysics》2004,161(11-12):2139-2153

— We quantify the effects of complex fault geometry on low-frequency (<1 Hz) strong ground motion using numerical modeling of dynamic rupture. Our tests include the computation of synthetic seismograms for several simple rupture scenarios with planar and curved fault approximations of the 1994 Northridge earthquake. We use the boundary integral equation method (BIEM) to compute the dynamic rupture process, which includes the normal stress effects along the curved fault geometries. The wave propagation and computation of synthetic seismograms are modeled using a fourth-order finite-difference method (FDM). The near-field ground motion is significantly affected by the acceleration, deceleration and arrest of rupture due to the curvature of the faults, as well as the variation in directivity of the rupture. For example, a 6-km-long hanging-wall or footwall splay with a maximum offset of 1 km can change 1-Hz peak velocities by up to a factor of 2-3 near the fault. Our tests suggest that the differences in waveform are larger on the hanging wall compared to those on the footwall, although the differences in amplitude are larger in the forward rupture direction (footwall). The results imply that kinematic ground motion estimates may be biased by the omission of dynamic rupture effects and even relatively gentle variation in fault geometry, and even for long-period waves.  相似文献