A Comprehensive Investigation of an Offshore Active Fault in the Western Sagami Bay, Central Japan   总被引：1，自引：0，他引：1  

Izumi SAKAMOTO  How Kin WONG 《《地质学报》英文版》2002,76(3):300-307

Offshore active faults, especially those in the deep sea, are very difficult to study because of the water and sedimentary cover. To characterize the nature and geometry of offshore active faults, a combination of methods must be employed. Generally, seismic profiling is used to map these faults, but often only fault-related folds rather than fracture planes are imaged. Multi-beam swath bathymetry provides information on the structure and growth history of a fault because movements of an active fault are reflected in the bottom morphology. Submersible and deep-tow surveys allow direct observations of deformations on the seafloor (including fracture zones and microstructures). In the deep sea, linearly aligned cold seep communities provide indirect evidence for active faults and the spatial migration of their activities.The Western Sagami Bay fault (WSBF) in the western Sagami Bay off central Japan is an active fault that has been studied in detail using the above methods. The bottom morphology, fracture  相似文献   

Water Resource Development in the Quaternary Ryukyu Limestone Regions of Japan:Application of the GIS to the Site Selection of Underground Dams     

Kaijun JIANG  Hiroyasu FURUKAWA  Yuji ONOYAMA  Testuro ESAKI 《《地质学报》英文版》2001,75(3):254-259

Based on the natural and social conditions as well as hydrogeological characteristics of the Ryukyu limestone, a major aquifer in the Ryukyu Islands, a conception of underground dam, was proposed in the early 1970s in order to develop ground water resources in the Quaternary Ryukyu limestone regions of Japan. The practice of nearly thirty years has shown that the underground dam is an environment-friendly and effective way for developing ground water in these regions.To further improve the technology associated with underground dam, the authors introduced related analytic methods. The application of the geographical information system technology to site selection of the underground dam is reported in this paper.  相似文献   

Rb−Sr age of Gaik granite,Ladakh batholith,northwest Himalaya     

J R Trivedi  K Gopalan  Kewal Kisharma  K R Gupta  V M Choubey 《Journal of Earth System Science》1982,91(1):65-73

The Gaik Granite is a part of the Ladakh batholith outcropping between Gaik and Kiari in NW Himalaya. This is a pink porphyritic granite rich in biotite and poor in hornblende. Rb-Sr analyses have been made on six whole-rock samples of the Gaik Granite. Though the samples are poorly enriched in radiogenic Sr, they define a reliable isochron corresponding to an age of 235±13 (2σ) m.y. and initial⁸⁷Sr/⁸⁶Sr ratio of 0·7081±0·0004 (2σ). Biotite, plagioclase and potash feldspar fractions separated from two of the samples have yielded a much younger mineral isochron at 30±1·5 m.y. indicating a nearly complete redistribution of Sr isotopes between mineral phases at a time much later than the primary emplacement of the granite. The present results show that at least some components of the Ladakh batholith are of Permo-Triassic age. These rocks were isotopically re-equilibrated on a mineral scale during Upper Oligocene in response to the Himalayan orogeny.  相似文献   

On the origin of the low energy cosmic rays from stellar sources     

S Biswas  N Durgaprasad  Sushma S Trivedi 《Journal of Earth System Science》1981,90(4):337-344

  相似文献   

Horizontal geomagnetic field variations at low latitude in South Atlantic Magnetic Anomaly     

N. D. Kaushika  N. B. Trivedi 《Pure and Applied Geophysics》1972,99(1):99-107

Summary Horizontal geomagnetic field variations on international quiet days at a low latitude station situated in the South Atlantic Magnetic Anomaly are studied with reference to the problem whether these variations are caused by the daytime increases or by the night time depressions of the field. It is found that both the mechanisms are operative significantly. The correction for noncyclic change decreases the magnitude of the night time depression. However, it does not account fully for the same. Possible causes for the night depressions are also discussed.  相似文献   

断层岩与断层模式   总被引：7，自引：0，他引：7  

林爱明 《高校地质学报》1996,2(3):295-306

本文通过对断层岩的结构、构造特征及其力学成因研究现状的综述，提出以下几点看法：（１）断层岩是在特定的地质环境下形成的，其结构特征直接反映所处境的地质构造运动特性所以通过研究断层岩的内部组构可以直接了解形变环境及其区域地质构造发展史；（２）断层财的线理和面理结构既可以在韧塑性条件下形成，也可以在脆性条件下形成，因此是否具有线理与面理结构不能作支岩分类的决定性基准；（３）断层岩母岩结晶的大小直接影响断  相似文献   

焉耆盆地活动构造的遥感图像特征   总被引：1，自引：1，他引：1       下载免费PDF全文

郭建明  傅碧宏  林爱明  狩野谦一  完山正 《地震地质》2003,25(2):195-202

焉耆盆地是一个位于天山东南部的山间盆地 ,在遥感图像上 ,可以看到盆地西面的活动构造在地表留下的痕迹 :清楚的线形构造 ,被错开的水系、冲沟等。经分析认为 ,这些活动构造主要由北边的活动褶皱和南边的右行走滑活动断裂组成。野外的实际调查与图像分析的结果十分吻合 ,表明遥感图像在研究活动构造方面是一个十分有力和快速的工具。活动断层的最大水平位移为 2 10m ,最大垂直位移为 2 0m ,主要以走滑作用为主。天山地区活动构造的发育表明印度板块向欧亚板块的碰撞仍在持续  相似文献   

DISTRIBUTION OF AEROSOL EXTINCTION IN THE LOWER TROPOSPHERE BY MICRO-PULSE LIDAR OBSERVATION          下载免费PDF全文

吴永华  胡欢陵  周军 《Acta Meteorologica Sinica》2000,(4)

The profiles of aerosol extinction coefficients are investigated by micro-pulse lidar(MPL)combined with the meteorological data in the lower troposphere at Meteorological ResearchInstitute(MRI).Japan.Larger extinction values of aerosol are demonstrated in the nocturnalstable air layer with larger Richardson number,and light wind velocities are favorable for aerosolconcentrating in the planetary boundary layer(PBL).But aerosol extinction coefficients showlarger values over the altitudes of 2.0 to 5.0km where correspond to higher relative humidity(RH).The tops of PBL identified by the aerosol extinction profiles almost agree with ones byradiosonde data.The diurnal variations of aerosol extinction profiles are clearly displayed,intensive aerosol layers usually are formed over the period of mid-morning to 1400 Loeal Time(LT).then elapse in the cloudless late afternoon and nighttime.Thermal eonvection or turbulenttransport from the surfaee probably dominates these temporal and spatial changes of aerosoldistribution.  相似文献   

Characteristics of Intraslab Stress Field and Tectonic Implication in the Nankai Trough, Japan     

XU Jiren  ZHAO Zhixin Institute of Geology  Chinese Academy of Geological Science  Beijing  China Kono Yoshiteru Faculty of Science  Kanazawa University  Kanazawa -  Japan 《Continental Dynamics》2000,(1)

1. IntroductionThe Nankai Trough region (Fig. 1.1) of southwest Japan is one of the most tectonically complex subduction zones in the world. The subduction of the Philippine Sea plate (PH) beneath the Eurasian plate (EU) has caused a series of large and great interplate earthquakes. It is generally accepted that great earthquakes have occurred at intervals of 100-150 years along the Nankai subduction zone since the 684 Hakuho earthquake (Fig. 1.2). However, a large earthquake (M>7.5) has…  相似文献   

Mechanisms of bottom boundary fluxes in a numerical model of the Shetland shelf     

Arjav Trivedi  Ralf Toumi 《Ocean Dynamics》2017,67(1):1-21

Across-slope bottom boundary layer (BBL) fluxes on the shelf-edge connect this region to deeper waters. Two proposed ways in which across-slope BBL fluxes can occur, in regions that have a slope current aligned to the bathymetry, are the frictional veering of bottom currents termed the ‘Ekman drain’ and through local wind-forced downwelling (wind-driven surface Ekman flow with an associated bottom flow). We investigate the variability, magnitude and spatial scale of BBL fluxes on the Shetland shelf, which has a prominent slope current, using a high-resolution (～2 km) configuration of the MITgcm model. Fluxes are analysed in the BBL at the shelf break near the 200 m isobath and are found to have a seasonal variability with high/low volume transport in winter/summer respectively. By using a multivariate regression approach, we find that the locally wind-driven Ekman transport plays no explicit role in explaining daily bottom fluxes. We can better explain the variability of the across-slope BBL flux as a linear function of the speed and across-slope component of the interior flow, corresponding to an Ekman plus mean-flow flux. We estimate that the mean-flow is a greater contributor than the Ekman flux to the BBL flux. The spatial heterogeneity of the BBL fluxes can be attributed to the mean-flow, which has a much shorter decorrelation length compared to the Ekman flux. We conclude that both the speed and direction of the interior current determines the daily BBL flux. The wind does not explicitly contribute through local downwelling, but may influence the interior current and therefore implicitly the BBL fluxes on longer timescales.  相似文献