The low seismic activity of the Korean Peninsula surrounded by high earthquake countries   总被引：1，自引：0，他引：1  

S.G. Kim  E. Lkhasuren  P.-H. Park 《Journal of Seismology》2004,8(1):91-103

Although the Korean Peninsula is locatednear several great earthquake regions suchas NE China and SW Japan, it has neversuffered from catastrophic earthquakes forthe last 2000 years according to historicaland instrumental records. We investigatedthe low seismicity of Korea based on thehypothesis of the Baikal-Korea Plate (BKP)or Amurian Plate movement which isinitiated by the Baikal Rift Zone spreadingin a southeastward motion with acounter-clockwise rotation due to thecollision of the Indian Plate against theEurasian Plate. Many disastrous earthquakesof NE China, SW Japan and Sakhalin releaselarge amounts of seismic energy along theboundary of the Baikal-Korea Plate. It isnecessary to compute the released seismicenergy along the presumed boundary of theBaikal-Korea Plate compared to the KoreanPeninsula in order to estimate themicro-plate boundary. The total energyreleases (1900–1999) from the majordisastrous earthquakes (M6.0) alongthe Baikal-Korea plate are about10³–10⁴ times as much as theKorean Peninsula (M3.0). The focalmechanisms for the intra-continentalearthquakes near and/or along theBaikal-Korea Plate boundary of NE China, SW Japan, Sakhalin and Mongolia mostlyrepresent the horizontal motions of theright-lateral strike slip type, indicatingthat the Baikal-Korea Plate is acounter-clockwise and transcurrent motion. The relative displacement vectors of GPS(global positioning system) also indicatedthat the Baikal-Korea Plate movescounter-clockwise around the KoreanPeninsula. These factors may indicate thatthe Korean Peninsula is not located at thePlate boundary, but just within a margin ofthe Baikal-Korea Plate which movessoutheastward with a counter-clockwiserotation from the Baikal Rift Zone in NEAsia. Therefore there is no enoughaccumulated strain to generate largeearthquakes in the Korean Peninsula and itmakes the Korean Peninsula free fromseismic hazard of large catastrophicearthquakes.  相似文献   

Interannual and long-term variation in the nearshore fish community of the mesohaline Hudson River estuary     

Thomas?P.?HurstEmail author  Kim?A.?McKown  David?O.?Conover 《Estuaries and Coasts》2004,27(4):659-669

The detection of long-term shifts in species composition and spatial structuring of aquatic communities may be obscured by high levels of interannual variation. Estuarine fish communities are likely to exhibit high levels of variation owing to the influence of riverine forcing and the importance of anadromous and transient species, whose abundances may not be locally controlled. We describe patterns of interannual variation and long-term shifts in the nearshore fish community of the mesohaline Hudson River estuary based on 21 yr of beach seine sampling conducted annually between late August and mid November. Of the 60 species encountered, the most abundant were Atlantic silversides (Menidia menidia), striped bass (Morone saxatilis), white perch (Morone americana), American shad (Alosa sapidissima), and blueback herring (Alosa aestivalis). Relationships between annual community composition and seasonal flow and temperature regimes were examined with canonical correspondence analysis. Annual variation was most closely correlated with river flows in the 3-mo period preceding fish sampling, indicating a persistent effect of environmental conditions on community structure. Despite significant interannual variation in composition, longer-term trends in community structure were observed. These included declines in catch rates of freshwater and estuarine species and a dramatic increase in the catch of Atlantic silversides, an annual marine species. Associated with these changes were declines in community diversity and increased compositional variation. These results indicate that analyses of temporal changes in community structure need to account for the multiple time scales under which forcing factors and community composition vary.  相似文献   

Is TOL 1326-379 a Prototype of γ-Ray Emitting FR0 Radio Galaxy?     

Wen-Jing Fu  Hai-Ming Zhang  Jin Zhang  Yun-Feng Liang  Su Yao  En-Wei Liang 《天文和天体物理学研究(英文版)》2022,(3):47-56

With the possible spacial association to the Fermi/LAT source 3FGL J 1330.0-3818,TOL 1326-379 may be the first one that is identified as a γ-ray emitting Fanaro...  相似文献   

Uniform head in horizontal and vertical wells   总被引：1，自引：0，他引：1  

Steward DR  Jin W 《Ground water》2006,44(1):86-90

The steady-state head within a fully penetrating well may be estimated by evaluating the Thiem equation at the radius of the well. A method is presented here to extend results from the Thiem equation to horizontal wells and to partially penetrating wells. The particular model used in this investigation is based upon the analytic element method; it accurately reproduces a boundary condition of uniform head along the cylindrical surface at the perforated face of the well. This model is exercised over a representative range of parameters including the well's length, radius, and pumping rate, and the aquifer's hydraulic conductivity and thickness. Results are presented in a set of figures and tables that compare the well's drawdown to the drawdown that would have been obtained using the Thiem solution with the same pumping rate and radius. A methodology is presented to estimate the head within a horizontal or partially penetrating well by adding a correction term to results that can be readily obtained from computer models of vertical fully penetrating wells. This approach may also be used to contrast the differences in head between horizontal and vertical wells of various lengths, radii, and placement elevations.  相似文献   

基于球面六边形网格系统的空间信息处理方法   总被引：3，自引：1，他引：2  

张永生  贲进  童晓冲  戴晨光 《测绘科学技术学报》2006,23(2):110-114

利用球面离散网格系统管理全球海量空间信息是一种受到普遍关注的新途径.文中提出的方法首先采用施奈德等积多面体投影将平面多分辨率六边形网格映射到球面构成网格系统;然后通过边界点四元组将球面六边形网格之间的空间关系转化为球面三角四叉树处理,利用扩展的QTM编码方案在3轴离散网格坐标系下实现了经纬度和单元地址码之间的转换;最后提出了单元分析和检索算法.实验结果表明,这种数据处理方法直接对单元地址编码进行操作,具有较高的效率.  相似文献   

Three-dimensional distributions of sewage markers in Tokyo Bay water--fluorescent whitening agents (FWAs)     

Managaki S  Takada H  Kim DM  Horiguchi T  Shiraishi H 《Marine pollution bulletin》2006,52(3):281-292

Three-dimensional distributions of fluorescent whitening agents (FWAs: more specifically, DSBP and DAS1), which are sewage-derived water-soluble markers, were observed in Tokyo Bay water through multi-layer sampling of water at 20 locations. In summer, FWAs predominated in the surface layers, with trace but significant concentration of FWAs in bottom water due to stratification of seawater. In winter, on the other hand, FWAs were extensively mixed into the bottom layers because of the vertical mixing of seawater. In the surface layer, FWA concentrations and the DSBP/DAS1 ratio (the concentration ratio of DSBP to DAS1) were lower in summer than in winter, suggesting more efficient photodegradation of FWAs in euphotic zones during the summer due to stronger solar radiation. Horizontally, FWAs were widely distributed over the surface layer of Tokyo Bay. Surface water with DSBP concentrations above 50ng/L, corresponding to <200 times dilution of sewage effluent, was found to have spread up to 10km from the coastline. In addition, an offshore decline in FWA concentrations was observed, showing a half-distance of 10-20km. The decrease was caused by dilution by seawater of fresh water containing FWAs. The eastern part of the bay was different with respect to surface layers, with higher concentrations seen in northeastern parts. Furthermore, dispersion of combined sewer overflow (CSO)-derived water mass was observed in Tokyo Bay after heavy rain.  相似文献   

Photosynthetic characteristics of dominant tree species and canopy in the broadleaved Korean pine forest of Changbai Mountains     

Wu Jiabing  Guan Dexin  Sun Xiaomin  Zhang Mi  Shi Tingting  Han Shijie  Jin Changjie 《中国科学D辑(英文版)》2006,49(2):89-98

Based on the light-photosynthesis response measurement at leaf level, combined with over-and under-canopy eddy covariance measurements, research on photosynthetic characteristics of single trees and forest canopy was conducted. The relationship between light intensity and photosynthetic rates for leaves and canopy can be well fitted by a non-rectangular hyperbola model. Mongolian oak presented a high light compensation point, L _cp (28 μmol·m^?2·s^?1), a light saturation point L _sp (>1800 μmol·m^?2·s^?1), and a maximal net photosynthetic rate P _max (9.96 μmol·m^?2·s^?1), which suggest that it is a typical heliophilous plant. Mono maple presented the highest apparent quantum efficiency α (0.066) but the lowest, L _cp (16 μmol·m^?2·s^?1), L _sp (≈800 μmol·m^?2·s^?1), and P _max (4.51 μmol·m^?2·s^?1), which suggest that it is heliophilous plant. Korean pine showed the lowest α value but a higher P _max, which suggest that it is a semi-heliophilous plant. At the canopy level, the values of both α and P _max approached the upper limit of reported values in temperate forests, while L _cp was within the lower limit. Canopy photosynthetic characteristics were well consistent with those of leaves. Both showed a high ability to photosynthesize. However, environmental stresses, especially high vapor pressure deficits, could significantly reduce the photosynthetic ability of leaves and canopy.  相似文献   

Fluid evolution in the Rushan lode gold deposit of Jiaodong Peninsula, eastern China   总被引：2，自引：0，他引：2  

Fang-Fang Hu  Hong-Rui Fan  Ming-Guo Zhai  Cheng-Wei Jin 《Journal of Geochemical Exploration》2006,89(1-3):161

The Rushan gold deposit in the Jiaodong Peninsula is currently the largest lode gold in China. Gold occurs mainly in pyrite- and polymetallic sulfide–quartz vein/veinlet stockworks. Fluid inclusions in the deposit are divided into three main types, namely CO₂–H₂O, H₂O–CO₂ ± CH₄ and aqueous ones. Microthermometric data show that the pre-gold fluids were CO₂-dominant (X_CO2 up to 0.53), and the total homogenization temperatures fall in the range of 298377 °C. These fluids, modified by fluid/wallrock reactions, gradually evolved into fluids with less CO₂ (X_CO2 = 0.010.19) in the main ore-forming stage, and the total homogenization temperatures range from 170 to 324 °C. Hydrogen and oxygen stable isotope data suggest that ore-forming fluids were mixture of magmatic and meteoritic origin. Co-occurrence of gold and sulfides implies that gold was most likely transported in the form of gold–sulfide complexes. The wide distribution of CO₂ inclusions means that the pH variation during gold transportation was controlled by CO₂ buffering.  相似文献   

Calibration of GPS receivers based on IGS and CORS techniques     

SHI Kun  QIU Yunfeng  ZHAO Biyun  NIE Jin  CHEN Yuhan 《地球空间信息科学学报》2012,15(3):213-217

  相似文献   

An evaluation of potential solar radio emission power threat on GPS and GLONASS performance   总被引：1，自引：1，他引：0  

Vladislav V. Demyanov  Edward L. Afraimovich  Shuanggen Jin 《GPS Solutions》2012,16(4):411-424

The L-band solar radio emission has recently been regarded as a potential threat to stable GPS and GLONASS performance. However, the threat has not been completely investigated or assessed so far. We evaluate in detail the occurrence of GPS/GLONASS signal tracking failures under the direct exposure of wideband solar radio emission. By means of theoretical analysis, we found that the solar radio emission power level of 1,000?sfu (solar flux units) or higher can cause GPS/GLONASS signal tracking failures especially at L2 frequency. In order to prove this evaluation, we investigated GPS/GLONASS signal tracking failures at L1 and L2 frequencies during power solar flares X6.5 (December 6, 2006) and X3.4 (December 13, 2006). Comparing these events with weaker solar flare X17.2 on October 28, 2003, we found that L2 signal tracking failures appeared when the solar radio emission power exceeds 1,000?sfu. Therefore, our theoretical and experimental results confirm the earlier results by other authors.  相似文献