New Bathymetry and Magnetic Lineations Identifications in the Northernmost South China Sea and their Tectonic Implications   总被引：12，自引：1，他引：12  

Shu-Kun Hsu  Yi-ching Yeh  Wen-Bin Doo  Ching-Hui Tsai 《Marine Geophysical Researches》2004,25(1-2):29-44

The seafloor spreading of the South China Sea (SCS) was previously believed to take place between ca. 32 and 15 Ma (magnetic anomaly C11 to C5c). New magnetic data acquired in the northernmost SCS however suggests the existence of E–W trending magnetic polarity reversal patterns. Magnetic modeling demonstrates that the oldest SCS oceanic crust could be Late Eocene (as old as 37 Ma, magnetic anomaly C17), with a half-spreading rate of 44 mm/yr. The new identified continent–ocean boundary (COB) in the northern SCS generally follows the base of the continental slope. The COB is also marked by the presence of a relatively low magnetization zone, corresponding to the thinned portion of the continental crust. We suggest that the northern extension of the SCS oceanic crust is terminated by an inactive NW–SE trending trench-trench transform fault, called the Luzon–Ryukyu Transform Plate Boundary (LRTPB). The LRTPB is suggested to be a left-lateral transform fault connecting the former southeast-dipping Manila Trench in the south and the northwest-dipping Ryukyu Trench in the north. The existence of the LRTPB is demonstrated by the different patterns of the magnetic anomalies as well as the different seafloor morphology and basement relief on both sides of the LRTPB. Particularly, the northwestern portion of the LRTPB is marked by a steep northeast-dipping escarpment, along which the Formosa Canyon has developed. The LRTPB probably became inactive at ca. 20 Ma while the former Manila Trench prolonged northeastwards and connected to the former Ryukyu Trench by another transform fault. This reorganization of the plate boundaries might cause the southwestern portion of the former Ryukyu Trench to become extinct and a piece of the Philippine Sea Plate was therefore trapped amongst the LRTPB, the Manila Trench and the continental margin.  相似文献   

An investigation on internal solitary waves in a two-layer fluid: Propagation and reflection from steep slopes   总被引：2，自引：0，他引：2  

Chen-Yuan Chen  John Rong-Chung Hsu  Min-Hung Cheng  Hsin-Hsun Chen  Ching-Feng Kuo 《Ocean Engineering》2007,34(1):171-184

Experimental investigations on internal solitary wave (ISW) propagation and their reflection from a smooth uniform slope were conducted in a two-layered fluid system with a free surface. A 12-meter-long wave flume was in use which incorporated with: (1) a movable vertical gate for generating ISW; (2) six ultrasonic probes for measuring the fluctuation of an ISW; and (3) a steep uniform slope (from one of θ=30°, 50°, 60°, 90°, 120° and 130°) much greater than those ever published in the literature. This paper presents the wave profile properties of the ISW recorded in the flume and their nonlinear features in comparison with the existing Korteweg de Vries (KdV) and modified Korteweg-de Vries (MKdV) theories. Experimental results show that the KdV theory is suitable for most small-amplituded ISWs and MKdV theory is appropriate for the reflected ISWs from various uniform slopes. In addition, both the amplitude-based reflection coefficient and reflected energy approach a constant value asymptotically when plotted against the slope and the characteristic length ratio, respectively. The reflected wave amplitudes calculated from experimental data agree well with those reported elsewhere. The optimum reflection coefficient is found within the limit of 0.85 for wave amplitude, among the test runs from steep normal slope of 30° to inverse angle of 130°, and around 0.75 for the reflected wave energy, produced by an ISW on a vertical wall.  相似文献   

Theory and application of calibration techniques for an NDBC directional wave measurements buoy   总被引：1，自引：0，他引：1  

Steele  K. Joseph Lau Yuan-Huang Hsu 《Oceanic Engineering, IEEE Journal of》1985,10(4):382-396

The National Data Buoy Center (NDBC) of the National Oceanic and Atmospheric Administration (NOAA) deployed a 10-m-diameter discus-type hull in the Pacific Ocean some 185 km southwest of Los Angeles, California, in April 1984. Aboard this hull was an electronic system capable of acquiring, processing, and transmitting to shore directional wave measurements. For this system to produce accurate data, a number of factors had to be taken into account. These factors included noise, amplitude and phase alterations due to mechanical and electrical components, and magnetic fields arising from the hull. Comprehensive calibration and verification techniques were developed and applied to ensure data quality. The system configuration is described with emphasis on the methods used in the data processing to correct for the various factors. Examples of the resulting corrected data are given.  相似文献   

Deformation Front Development at the Northeast Margin of the Tainan Basin, Tainan–Kaohsiung Area, Taiwan     

Shiuh-Tsann Huang  Kenn-Ming Yang  Jih-Hao Hung  Jong-Chang Wu  Hsin-Hsiu Ting  Wen-Wei Mei  Shiang-Horng Hsu  Min Lee 《Marine Geophysical Researches》2004,25(1-2):139-156

The geological setting south of the Tsengwen River and the Tsochen Fault is the transitional zone between the Tainan foreland basin and Manila accretionary wedge in Southwestern Taiwan. This transitional zone is characterized by the triangle zone geological model associated with back thrusts that is quite unique compared to the other parts of the Western foreland that are dominated by thrust imbrications. The Hsinhua structure, the Tainan anticline, and the offshore H2 anticline are the first group of major culminations in the westernmost part of the Fold-and-Thrust belt that formed during the Penglay Orogeny. Structures in the the Tainan and Kaohsiung areas provide important features of the initial mountain building stage in Western Taiwan. A deeply buried basal detachment with ramp-flat geometry existed in the constructed geological sections. A typical triangle is found by back thrusting, such as where the Hsinhua Fault cuts upsection of the Upper Pliocene and Pleistocene from a lower detachment along the lower Gutingkeng Formation. The Tainan structure is a southward extension of the Hinhua Fault and has an asymmetric geometry of gentle western and steep eastern limbs. Our studies suggest that the Tainan anticline is similar to the structure formed by the Hsinhua Fault. Both are characterized by back thrusts and rooted into a detachment about 5 km deep. The triangle zone structure stops at H2 anticline offshore Tainan and beyond the west of it, All the structures are replaced by rift tectonic settings developed in the passive continental margin. On the basal detachment, a major ramp interpreted as a tectonic discontinuity was found in this study. Above the northeastern end of the major ramp of basal detachment, the Lungchuan Fault is associated with a triangle system development, while at the southwestern end a thrust wedge is present. It could be deduced that a thrust wedge intrudes northwestward. The area below the major ramp, or equivalent to the trailing edge of the basal detachment, mud diapers often occur in relation to the thickest deposits of the Gutingkeng Formation and caused by the mechanism of detachment folding  相似文献   

Calculations of wave transformation across the surf zone     

Ching-Piao Tsai  Hong-Bin Chen  John R. -C. Hsu 《Ocean Engineering》2001,28(8)

The accuracy of predicting wave transformation in the nearshore is very important to wave hydrodynamics, sediment transport and design of coastal structures. An efficient numerical model based on the time-dependent mild-slope equation is presented in this paper for the estimation of wave deformation across the surf zone. This model incorporates an approximate nonlinear shoaling formula and an energy dissipation factor due to wave breaking to improve the accuracy of the calculation of wave height deformation prior to wave breaking and also in the surf zone. The model also computes the location of first wave breaking, wave recovery and second wave breaking, if physical condition permits. Good agreement is found upon comparison with experimental data over several one-dimensional beach profiles, including uniform slope, bar and step profiles.  相似文献   

The growth of Chinese minority populations     

Hsu M 《GeoJournal》1993,30(3):279-282

The 55 recognized minority races in PRChina have a total population of 91.2 million. These peoples are distributed widely in two–thirds of China's territories.The minority population has grown rapidly since the 1960s. In this paper, I examine the major causes of this growth. They are the significant improvement of public health in the 1950s and 1960s, the leniency in the implementation of the birth control policies in minority communities, the relatively high birth and fertility rates in these communities, and the reaffirmation of racial identity in the 1980s.Most minority settlements are located in the less developed interior of China. Some of these areas are rich in minerals but they are not used most efficiently. Meanwhile, the land is over used. Today the Chinese advocate a faster economic development and a stricter birth control program for these areas.  相似文献   

我国动力大地测量学的进展   总被引：8，自引：0，他引：8  

HSU Houtze  蒋福珍  张赤军 《地球科学进展》2000,15(2):127-133

综合了近40年,特别是近10年来我国利用大地测量学、地球物理学和天体测量学的理论、方法和技术研究固体潮汐和非潮汐重力、地极移动和自转速率变化、大地水准面和海平面变化、板块运动和地壳形变、地球内部物质运动及其与地表变化的关系等五个方面的成果以及国际合作的情况,说明我国在动力大地测量学方面虽然起步较晚,但进展较快,已在生态环境、灾害预测预报等关系国计民生的研究中起到了一定作用,在国内国际的地学研究中占有一席之地。随着国际大地测量协会“亚太空间动力学研究计划”、国家攀登计划项目“现代地壳运动和地球动力学研究”、国家大型科学工程重大项目“中国地壳运动观测网络”等项目的启动、实施,动力大地测量学研究必将取得快速进展。  相似文献   

Detecting surface geostrophic currents using wavelet filter from satellite geodesy   总被引：4，自引：0，他引：4  

HSU HouTse 《中国科学D辑(英文版)》2007,50(6):918-926

According to the features of spatial spectrum of the dynamic ocean topography (DOT),wavelet filter is proposed to reduce short-wavelength and noise signals in DOT. The surface geostrophic currents calculated from the DOT models filtered by wavelet filter in global and Kuroshio regions show more detailed information than those from the DOT models filtered by Gaussian filter. Based on a satellite gravity field model (CG01C) and a gravity field model (EGM96),combining an altimetry-derived mean sea surface height model (KMSS04),two mean DOT models are estimated. The short-wavelength and noise signals of these two DOT models are removed by using wavelet filter,and the DOT models asso-ciated global mean surface geostrophic current fields are calculated separately. Comparison of the surface geostrophic currents from CG01C and EGM96 model in global,Kuroshio and equatorial Pacific regions with that from oceanography,and comparison of influences of the two gravity models errors on the precision of the surface geostrophic currents velocity show that the accuracy of CG01C model has been greatly improved over pre-existing models at long wavelengths. At large and middle scale,the surface geostrophic current from satellite gravity and satellite altimetry agrees well with that from oceanography,which indicates that ocean currents detected by satellite measurement have reached relatively high precision.  相似文献   

Check of Earth’s free oscillations excited by Sumatra-Andaman Large Earthquake and discussions on the anisotropy of inner core     

Lei XiangE  Sun HePing  Hsu HouTse  Shi YaoLin 《中国科学D辑(英文版)》2007,50(6):909-917

Sumatra-Andaman Large Earthquake on Dec. 26, 2004 generated not only the Indian Ocean Tsunami but also the Earth’s free oscillations (EFO). The signals of Earth’s free oscillations were perfectly recorded by the superconducting gravimeter C0-32 at Wuhan station in China. After the pre-treatment and spectral analysis on the observational data from Wuhan station, we obtained more than ninety EFO modes including 42 fundamental modes, 2 radial modes and 49 harmonic modes. On the basis of the discussions on some observed harmonic modes and abnormal splitting phenomena, we considered that the real rigidity might be lower than the theoretical prediction of PREM model in the inner core and however the anisotropy of compressive wave was brightly higher than the present estimations in the inner core. This suggested that the anisotropy of the inner core could be much more complicated than our present understanding, and there might be some new geophysical phenomena in the formation process of the inner core. Supported jointly by the National Natural Science Foundation of China (Grant Nos. 40404005 and 40374029) and the Excellent Prize of President Scholarship and Hundred Talents Program of the Chinese Academy of Sciences  相似文献   

潮汐解算中地核问题的分析   总被引：8，自引：0，他引：8  

彭龙辉  李国营  许厚泽 《测绘学报》1998,27(4):287-292

随着地球模型越来越接近真实地球,对潮汐的数值模拟理论也不断深化,潮汐解算过程中随之将出现新的问题。在解算三维地球模型潮汐响应前,首先要获得径向对称地球模型沿径向的分布,其中最大的困难是在地核中的解算,本文通过一转换解决了这一问题。  相似文献