组合VLBI和SLR数据估计的全球板块运动参数

本文组合应用ＶＬＢＩ和ＳＬＲ数据导出了一个完全基于空间技术实测数据的现时板块运动模型，称为ＳＧＰＭＭ１。ＳＧＰＭＭ１与地学板块运动模型ＮＵＶＥＬ－１的比较指出：空间大地测量数据估计的板块运动总体上与地学估计值一致。经过地磁极倒转时间尺度修正，并考虑到冰斯后地壳回弹的影响，空间大地测量数据估计的北美，欧亚和澳大利亚板块之间的相对运动速率与地学估计值有极好的一致，但太平洋板块相对于北美、欧亚和澳大利亚     

利用空间技术建立绝对板块运动模型

利用欧拉定律和ITRF2005的速度场,给出了全球板块运动模型ITRF2005VEL,并计算了全球地壳旋转总角动量之和。采用离散的Tisserand条件对实测的全球台站运动速度进行约束,建立了一个新的基于NNR参考框架的实测的绝对板块运动模型NNR-ITRF2005,并与地学模型NNR-NUVEL1A和ITRF其他序列建立的NNR模型进行了比较和分析。结果表明,从整体上来看,NNR-ITRF2005比较接近于NNR-NU-VEL1A,但个别板块由于测站较少、分布不均或者测站观测时间短对板块的约束不够等原因,使得这些板块的欧拉极与地学模型的偏差较大。     

CGCS2000板块模型构建

基于中国地壳运动观测网络2001—2010年跨度长达10年的观测数据,采用基准优选、变异点数据分段处理等策略,计算获得ITRF2005框架下高精度速度场。同时针对国际上现有的NNR NUVEL1A、APKIM2005、PB2002等板块模型在中国区域适应性差,基于中国地质构造特性及实际速度场解算结果,构建了中国20个二级板块模型CPM-CGCS2000。采用本文提出的用板块模型参数将站点归算至CGCS2000的方法对板块模型进行外部检核,并用此方法验证所建的二级块体模型,精度可达2～3 cm。与国际上现有比较成熟的速度场模型———ITRF2005、APKIM2005、PB2002、NUVEL1A及国内文献[1—2]的板块模型进行的比较表明,CPM-CGCS2000板块模型实际精度优于目前现有的模型。     

基于全球板块运动模型分析大西洋扩张变化

基于现代空间测量技术SLR、VLBI和GPS实测资料，解算出大西洋中脊海底扩张速率，其中北大西洋的东西向扩张速率平均为35mm/a，赤道大西洋东西向扩张速度分别为20－25mm/a，南大西洋东西向扩张速率为22－28mm/a，证实全球板块运动的存在及大西洋扩张学说，并基于全球几百万年地质模型NNR－NUVEL1A，北大西洋的东西向扩张速率平均为24．3mm/a，基于最新全球板块运动模型ITRF2000VEL，北大西洋的东西向扩张速率平均为20．8mm/a，总体上大西洋实测东西扩张速度与根据地学资料推出的地球板块运动模型和最新ITRF2000VEL模型的结果基本一致。     

基于VLBI、SLR和GPS实测数据的现时板块运动模型

采用空间大地测量技术 (VL BI、 SLR、 GPS)实测板块运动的最新数据 ,导出了全球 7个主要板块 (欧亚、北美、太平洋、澳大利亚、非洲、南美、南极板块 )之间的相对运动欧拉矢量 ,建立了一个完全基于空间大地测量观测的现时板块运动模型 ,称为 SGPMM2。与地学板块运动模型 NUVEL-1 A相比两者基本一致 ,说明最近 3百万年内全球板块运动总体上是稳定的。作者还首次导出了南中国板块相对于欧亚板块的相对运动欧拉矢量 (2 0 .5°S,67.2°W,0 .3 0 0°/ Ma)。与 Armijo等 (1 989)根据欧亚板块内北西藏块体与周围块体的断层走向和滑动速率估计的北西藏块体相对于欧亚板块的欧拉矢量 (1 7.0°S,61 .4°W,0 .45 8°/Ma)相比 ,两者运动方向一致 ,但南中国板块的运动速率稍小。作为对印度板块高速插入欧亚板块之下的响应 ,这个结果证实了南中国板块受西藏块体东向挤压而向东南运动的构造学推断。     

多面函数拟合法及其在建立中国地壳平面运动速度场模型中的应用研究

基于现有的GPS观测值，将多面函数拟合法用于速度场模型的建立，得到了目前中国覆盖范围最广、分布最均匀、有实用价值的中国地壳平面运动整体速度场图像和NNR－NUVEL1A全球板块运动模型下的平面运动速度场图像。     

利用空间技术求解现时板块运动参数

本文综合利用GPS及VLBI技术，以站心坐标速度为观测量，求解了五个主要板块的绝对和相对板块运动参数，进行了精度分析。并与传统的NUIVEL-1 A地学板块运动模型进行了比较，在一定程度上说明全球板块运动在最近300万年内总体上趋于稳定。     

用甚长基线干涉测量（VLBI）数据导出的板块运动参数

本文采用最近获得的ＶＬＢＩ基线变化率，解算了全球５０个ＶＬＢＩ站的站速度。通过对ＶＬＢＩ台站构造稳定性的分析，用位于板块稳定地区台站的站速度求解了欧亚（ＥＵＲＡ）、北美（ＮＯＡＭ）和太平洋（ＰＣＦＣ）三个主要板块之间的相对运动欧拉矢量，这是完全基于ＶＬＢＩ数据导出的板块运动模型，称为ＶＰ－ＭＭ１。通过ＶＰＭＭ１与地学板块运动模型的比较，分析了板块运动的稳定性，得出了几点初步结论。     

现今板块运动模型的发展及其比较

从地质数据的不断完善到空间大地测量数据的广泛应用,现今板块运动模型的发展有了质的飞跃.评述了其现状与发展趋势;利用ITRF2005的速度场建立了一个完全基于现代空间大地测量实测结果的现今全球板块运动模型ITRF2005VEL,并与地质模型NNR-NUVEL1A进行了比较.结果表明,从整体上看ITRF2005VEL与NNR-NUVEL1A模型有较好的一致性,且较以往的ITRF序列的模型精度更高,但同时也存在着一定的差异性,这与观测台站、板块本身等相关因素都有关.     

大洋海岭相对运动的测定及其分析

基于现今实测全球板块运动模型ITRF2000VEL，分别建立了相对东太平洋海岭和南北大西洋海岭的绝对板块运动模型PRF-ITRF2000VEL、SRF-ITRF2000VEL和NRF-ITRF2000VEL，由此分析了大洋海岭间的相对运动，表明大西洋海岭与东太平洋海岭以平均10．9mm/a的速度在张开，反映了大洋海岭并非固定，由此得到的绝对板块运动模型均是“相对”的绝对板块运动模型。     

Results of the VLBI experiments conducted with Syowa Station, Antarctica

The first successful geodetic Very Long Baseline Interferometry (VLBI) observations to Antarctica were made on baselines from Syowa Station (Antarctica) to Tidbinbilla (Australia) and to Kashima (Japan) in January 1990. Regular geodetic experiments started in 1998 with the installation of a permanent VLBI terminal at Syowa Station. These observations are conducted at the standard geodetic VLBI frequencies of 2.3 and 8.4 GHz, S- and X-Bands. In the first year, the 11-m multipurpose antenna at Syowa Station observed together with the 26-m radio telescope of the University of Tasmania in Australia and the 26-m radio telescope of the Hartebeesthoek Radio Astronomy Observatory in South Africa. From 1999, the experiments were expanded to also include the O’Higgins Station in Antarctica, Fortaleza in Brazil and Kokee on Hawaii. From 1999 until the end of 2003, 25 observing sessions have been reduced and analyzed using the CALC/SOLVE geodetic VLBI data reduction package. The results show that the horizontal baseline of Syowa-Hobart is increasing at the rate of 57.0±1.9 mm/year. The baseline Syowa-Hartebeesthoek is also increasing, but at the lower rate of 9.8±1.9 mm/year. The VLBI result of 2.0±3.1 mm/year and the GPS result of −1.9±0.7 mm/year for the Syowa-O’Higgins horizontal baseline support the hypothesis of one rigid Antarctic plate without intra-plate deformation, which is consistent with the NNR-NUVEL-1A global plate motion model. The location of the Euler pole of the Antarctic plate by VLBI is estimated as 59.7°S and 62.6°E with a rotation rate of 0.190 deg/Myr, while that by GPS in our study is estimated as 60.6°S and 42.2°E with a rotation rate of 0.221 deg/Myr. These pole positions are slightly different to that implied by the NNR-NUVEL-1A model of 63.0°S and 64.2°E with a rotation rate of 0.238 deg/Myr. VLBI observations over a longer time span may resolve small discrepancy of current plate motion from the NNR-NUVEL-1A model. The consistency of the VLBI coordinates with the GPS coordinates at Syowa Station, after correction for the local tie vector components between the two reference markers, is also discussed.     

Present-day crustal deformation in China relative to ITRF97 kinematic plate model

 A global plate motion model is established based on the ITRF97 velocity fields and geological model NUVEL1. Sub-plate models are estimated by using the velocity fields derived from 45 global positioning system (GPS) sites under the ITRF97 reference frame in China. Comparisons between space geodesy and geological models are given. It is found that the Euler vector of the AFRC–EURA pair has an obvious discrepancy between space geodetic and geological models. The motion patterns of tectonic blocks in China predicted by GPS are consistent with those of geological data on the whole. Received: 9 November 2000 / Accepted: 17 September 2001     

空间技术观测数据对全球七大板块运动参数的精化

采用截止到2003年GPS观测数据和1997年的VLBI观测数据,利用它们的站速度信息,组合解算完全基于空间技术的板块运动参数;通过对站速度残差的精化分析,得出更加稳健的现时板块运动参数;并通过反复试算得出稳定台站的选取以及台站的分布对板块运动欧拉极有很大的影响。     

抗差主成分估计在板块运动参数解算中的应用

为解决在采用空间大地测量数据求解板块运动欧拉参数过程中可能出现的矩阵病态问题,以及消除粗差对解算结果的影响,利用抗差主成分估计方法,采用IGG3方案的选权迭代方案对北美板块的2 577个台站进行检测,剔除包含粗差的异常站数据,求出欧拉参数最优解,并进行误差估计,建立北美板块的运动模型。计算结果表明,剔除异常台站前后精度有一定的提高,参数结果与其他模型的解算结果具有较强的一致性。     

On rotation of frames and physical vectors: an exercise based on plate tectonics theory

The mathematical interaction between the simultaneous rotation of both a coordinate frame and a set of physical vectors in that frame is covered and theoretically and empirically explained. A practical example related to the secular motion of the pole determined using recent GPS results is addressed. A least-squares adjustment is introduced to determine a possible displacement of the geodetic north pole of the frame caused by plausible changes in the coordinates of the observing stations defining the frame due to the rotation of the plates on which these stations are located. Two examples of GPS networks are investigated both referred to the latest definition of the IGS08 geodetic frame. The positioning and velocities of the points were exclusively obtained using GPS data as published by the International GNSS Service (IGS). The first case comprises the complete GPS/IGS network of global stations; the second one assumes the closest GPS/IGS stations to the now discontinued International Latitude Service network. The results of this exercise hints at the possibility that the secular global rotation of the frame caused by plate rotations should be accounted for in order to rigorously determine the true absolute velocities referred to the IGS frame before the actual velocities of the rotation of the plates using GPS observations are published.     

New global positioning system reference station in Brazil

Co-located very long baseline interferometry (VLBI) and global positioning system (GPS) reference stations were installed near Fortaleza, Brazil, in 1993. Both have been important in the realization and maintenance of the International Terrestrial Reference Frame. A new-generation GPS system was installed in 2005 to replace the original station. Experience gained in the prior 12 years was used to improve the design of the GPS antenna mount. Preliminary indications are greatly improved data quality from the new station. Simultaneous observations from the nearly half-year of overlapping operation have been used to determine the local tie between the new and old GPS reference points to about 1 mm accuracy. This can be used to update the 1993 survey tie between the original GPS and the VLBI points, although there are questions about the accuracy of that measurement based on a comparison with space geodetic data. A test of removing the conical radome over the old GPS antenna indicates that it has biased the station height by about 16 mm downward, which probably accounts for most of the previous survey discrepancy.     

EPC: Matlab software to estimate Euler pole parameters

The estimation of Euler pole parameters has always been an important issue in global tectonics and geodynamics studies. In addition, the increasing number of permanent GPS stations and the ease of access to their data, along with advances in computers, promise new methods and tools for the estimation and the quantitative analysis of Euler pole parameters. Therefore, we developed the Euler pole calculator software using a set of mathematical algorithms based on the model of tectonic plate motion on a spherical surface. The software is able to calculate the expected velocities for any points located on the earth’s surface given the relevant Euler pole parameters and to estimate the Euler pole parameters given the observed velocities of a set of sites located on the same tectonic plate. Mathematical algorithms and functions of the software are explained in detail.