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基于MCBI的网络RTK流动站定位精度分析 总被引：1，自引：1，他引：0
介绍了改进的综合误差内插法,使用高精度GPS解算软件,结合广州、江苏和天津CORS网对流动站进行了后处理,分析了不同星历类型和不同纬度下流动站定位精度,得到了一些有益的结论。 相似文献
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地球内部物质组成的研究涉及对地表现象的深入解释,与地球动力学、地球热结构及宇宙演化有着密切的关系.本文综述了这方面的研究结果及近期的进展,指出两种地幔模型的主要分歧点,讨论了地幔中的主要相变及与间断面的关系,对今后研究提出四点意见. 相似文献
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Zhen Guo Yuliang Cao Xianguang Wang Y. John Chen Jieyuan Ning Weiguang He Youcai Tang Yongge Feng 《地震科学（英文版）》2014,27(3):265-275
P-wave and S-wave receiver function analyses have been performed along a profile consisted of 27 broadband seismic stations to image the crustal and upper mantle discontinuities across Northeast China. The results show that the average Moho depth varies from about 37 km beneath the Daxing’anling orogenic belt in the west to about 33 km beneath the Songliao Basin, and to about 35 km beneath the Changbai mountain region in the east. Our results reveal that the Moho is generally flat beneath the Daxing’anling region and a remarkable Moho offset (about 4 km) exists beneath the basin-mountain boundary, the Daxing’anling-Taihang Gravity Line. Beneath the Tanlu faults zone, which seperates the Songliao Basin and Changbai region, the Moho is uplift and the crustal thickness changes rapidly. We interpret this feature as that the Tanlu faults might deeply penetrate into the upper mantle, and facilitate the mantle upwelling along the faults during the Cenozoic era. The average depth of the lithosphere-asthenosphere boundary (LAB) is ~80 km along the profile which is thinner than an average thickness of a continental lithosphere. The LAB shows an arc-like shape in the basin, with the shallowest part approximately beneath the center of the basin. The uplift LAB beneath the basin might be related to the extensive lithospheric stretching in the Mesozoic. In the mantle transition zone, a structurally complicated 660 km discontinuity with a maximum 35 km depression beneath the Changbai region is observed. The 35 km depression is roughly coincident with the location of the stagnant western pacific slab on top of the 660 km discontinuity revealed by the recent P wave tomography. 相似文献
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The 2008 Wenchuan earthquake, a major intraplate earthquake with M w 7.9, occurred on the slowly deforming Longmenshan fault. To better understand the causes of this devastating earthquake, we need knowledge of the regional stress field and the underlying geodynamic processes. Here, we determine focal mechanism solutions (FMSs) of the 2008 Wenchuan earthquake sequence (WES) using both P-wave first-motion polarity data and SH/P amplitude ratio (AR) data. As P-wave polarities are more reliable information, they are given priority over SH/P AR, the latter of which are used only when the former has loose constraint on the FMSs. We collect data from three categories: (1) permanent stations deployed by the China Earthquake Administration (CEA); (2) the Western Sichuan Passive Seismic Array (WSPSA) deployed by Institute of Geology, CEA; (3) global stations from Incorporated Research Institutions for Seismology. Finally, 129 events with magnitude over M s 4.0 in the 2008 WES are identified to have well-constrained FMSs. Among them, 83 are well constrained by P-wave polarities only as shown by Cai et al. (Earthq Sci 24(1):115–125, 2011), and the rest of which are newly constrained by incorporating SH/P AR. Based on the spatial distribution and FMSs of the WES, we draw following conclusions: (1) the principle compressional directions of most FMSs of the WES are subhorizontal, generally in agreement with the conclusion given by Cai et al. (2011) but with a few modifications that the compressional directions are WNW–ESE around Wenchuan and ENE–WSW around Qingchuan, respectively. The subhorizontal compressional direction along the Longmenshan fault from SW to NE seems to have a left-lateral rotation, which agrees well with regional stress field inverted by former researchers (e.g., Xu et al., Acta Seismol Sin 30(5), 1987; Acta Geophys Sin 32(6), 1989; Cui et al., Seismol Geol 27(2):234–242, 2005); (2) the FMSs of the events not only reflected the regional stress state of the Longmenshan region, but also were obviously controlled by the faults to some extent, which was pointed out by Cai et al. (2011) and Yi et al. (Chin J Geophys 55(4):1213–1227, 2012); (3) while the 2008 Wenchuan earthquake and some of its strong aftershocks released most of the elastic energy accumulated on the Longmenshan fault, some other aftershocks seem to occur just for releasing the elastic energy promptly created by the 2008 Wenchuan earthquake and some of its strong aftershocks. (4) Our results further suggest that the Longmenshan fault from Wenchuan to Beichuan was nearly fully destroyed by the 2008 Wenchuan earthquake and accordingly propose that there is less probability for great earthquakes in the middle part of the Longmenshan fault in the near future, although there might be a barrier to the southwest of Wenchuan and it is needed to pay some attention on it in the near future. 相似文献
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Euler vectors of 12 plates, including Philippine Sea plate (PH), relative to a randomly fixed Pacific plate(PA) were determined
by inverting the 1122 data from NUVEL-1 global plate motion model, earthquake slip vectors along Philippine Sea plate boundary,
and GPS observed velocities. Euler vectors of Philippine Sea plate relative to adjacent plates are also gained. Our results
are well consistent with observed data and can satisfy the geological and geophysical constraints along the Caroline(CR)-PH
and PA-CR boundaries. Deformation of Philippine Sea plate is also discussed by using the plate motion Euler parameters. 相似文献
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Intermediate-depth earthquakes beneath the Pamir-Hindu Kush Region:Evidence for collision between two opposite subduction zones 总被引：1，自引：0，他引：1
We employed a double-difference algorithm(hypoDD)to relocate earthquakes within the region bounded by 66°E-78°E and 32°N-42°N in the period of 1964?2003 reported by the International Seismological Center(ISC).The improved hypocentral locations delineate a double-layered Wadati-Benioff zone in the eastern Hindu Kush intermediate seismic belt.Based on this feature and other evidences,we propose that the intermediate-depth earthquakes beneath the Pamir-Hindu Kush region may occur in two collided subduction zon... 相似文献
9.
Yongcai Tang Yongshun John Chen Yuanyuan V. Fu Haiyang Wang Shiyong Zhou Eric Sandvol Jieyuan Ning Yongge Feng Mian Liu 《地震科学（英文版）》2010,23(6):549-553
Located at the northeastern margin of the Tibetan plateau,the Ordos block is a stable tectonic unit in North China.With its active boundary fault zones,the Ordos block played an important role in the eastward extrusion mechanism of the Tibetan plateau.Peking University deployed a linear array of 15 portable broadband seismometers across the western Weihe graben during September 2005 to August 2006 and later a 2-D seismic array(Southwest Ordos Array) of 14 portable broadband seismometers during 2007-2008 at its southwestern boundary.Analyses of shear wave splitting of SKS and SKKS phases at these stations show that the fast directions trend ～110° with an average delay time of 0.9 s in the southwestern margin of the Ordos block.The agreement between the lithosphere deformation indicated by GPS data and Quaternary fault slip-rate observations and the mantle flow represented by shear wave splitting implies that accordant deformation patterns from lithosphere to asthenosphere in relation to the eastward extrusion of the Tibetan plateau could extend at least to 200 km depth.Spatial distribution of splitting polarization directions indicates that the mantle flow driven by the Tibetan plateau is blocked by the Ordos block and locally restricted in a narrow channel along the Qinling-Dabie fault zones between the Ordos block and Sichuan basin. 相似文献
10.
美国哈佛大学1977——2004年的矩心矩张量结果显示, 我国川西北次级地块、 滇中次级地块的西部及滇中次级地块的东部的应力场特征有明显的差别. 应用滑动矢量拟合法, 反演了这三个区域的应力场特征: 川西北次级地块以近南北向的水平主张应力轴和西倾的主压应力轴为特征; 滇中次级地块的西部以倾向北东东的主张应力轴以及近南北的水平中等主应力轴为特征; 滇中次级地块的东部以南西西——北东东向的水平主张应力轴以及北北西——南南东向的水平主压应力轴为特征. 有限元模拟结果清楚地显示出, 川滇地块在阿萨姆楔附近受到来自印度板块的强烈挤压, 随着远离阿萨姆楔, 这种挤压应力逐渐衰减; 同时, 该地区的主张应力方向明显地形成了围绕阿萨姆楔的环线. 其中, 内部物质性质均匀、 地表和底部边界自由、 侧部边界采用GPS观测约束的弹性有限元模拟显示, 在川西北次级地块, 模拟结果与震源机制解结果相一致; 在滇中次级地块, 模拟结果所显示的图象与震源机制解观测结果有差别, 不仅没有显示出与大面积的东部地区的震源机制解相一致的特征, 反而显示出与该地区西部震源机制解相一致的特征. 通过调节地块内部物质的弹性常数, 可以实现在滇中次级地块东部部分地区出现与震源机制 相似文献