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2003年, 第23卷, 第S1期
刊出日期：2003-12-31
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大地测量与地球动力学. 2003, 23(S1): 1-7. https://doi.org/10.14075/j.jgg.2003.s1.001This is a summarized paper. Two topics are discussed: Firstly, the concept, development and application of four kinds of satellite gravity surveying technology are introduced; Secondly, some problems of theory and method, which must be considered in the study of the Earth’s gravity field based on satellite gravity data, are expounded.
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大地测量与地球动力学. 2003, 23(S1): 8-13. https://doi.org/10.14075/j.jgg.2003.s1.002The paper gives an overview of the principle and application of generating DEM from SAR, including the principle and processing flow of generating DEM from single SAR and SAR interferometry. Afterwards, the application fields of InSAR for terrain surveying, volcanic terrain surveying and D-InSAR for monitoring ground subsiding are listed and described as well. The problem and prospect of application are also pointed out in the last part of this paper.
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大地测量与地球动力学. 2003, 23(S1): 14-18,29. https://doi.org/10.14075/j.jgg.2003.s1.003The propagation path of satellite signals in the atmosphere is a curve thus it is very difficult to calculate its flexure correction accurately, a strict calculating expressions has so far not been derived. In this study, the flexure correction of the refraction curve is divided into two parts and their strict calculating expressions are derived. By use of the standard atmospheric model, the accurate flexure correction of the refraction curve is calculated for different zenith distance Z. On this basis, a calculation model is structured. This model is very simple in structure, convenient in use and high in accuracy. When Z is smaller than 85°,the accuracy of the correction exceeds 0.06 mm. The flexure correction is basically proportional to tan 2 Z and increases rapidly with the increase of Z. When Z >50°,the correction is smaller than 0.5 mm and can be neglected. When Z >50°, the correction must be made. When Z is 85°, 88° and 89°, the corrections are 198 mm, 8.911 m and 28.497 km, respectively. The calculation results shows that the correction estimate by Hopfield is correct when Z ≤80 °, but too small when Z =89°. The expression in this paper is applicable to any satellite.
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大地测量与地球动力学. 2003, 23(S1): 19-22. https://doi.org/10.14075/j.jgg.2003.s1.004In this paper, adjustment factors J and R put forward by professor Zhou Jiangwen are introduced and the nature of the adjustment factors and their role in evaluating adjustment structure is discussed and proved.
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大地测量与地球动力学. 2003, 23(S1): 23-29. https://doi.org/10.14075/j.jgg.2003.s1.005The QUAD(Quasi-Accurate Detection of gross errors) method which is originally developed to detect gross errors in the geodetic data is extended and used to select and identify relatively stable stations. The formulas and algorithm are described in detail. Some problems that should be noticed in the use of this method are discussed. Finally, this method is applied to some data observed in North China as an example.
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大地测量与地球动力学. 2003, 23(S1): 30-33,49. https://doi.org/10.14075/j.jgg.2003.s1.006In accordance with the geometric equations of elastic mechanics in the sphere coordinates, the displacement equation of blocks on asphere consisting of 6 deforming parameters is developed. The formula for distance between blocks is derived under the supposition that all block boundaries are prime arcs. The kinematic constraint and the penalty function for reasonable contact between blocks are developed. The normal equations and their coefficient matrix, based on the Least Squares Principle, are derived. The problem of adjudging penetration between blocks is discussed, and a solution is proposed.
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大地测量与地球动力学. 2003, 23(S1): 34-40. https://doi.org/10.14075/j.jgg.2003.s1.007Bouguer gravity anomaly in North China is decomposed with multi scale decomposition technique of wavelet transform. Gravity anomalies produced by anomalous density bodies of various scales are revealed from surface to Moho. Characteristics of anomalies of different orders and corresponding structural features are discussed. The result shows that details of wavelet transform of different orders reflect the distribution features of rock density at different depths and in various scales. In most cases, the two sides of a fault especially a deep and large fault in North China differ greatly in rock density. This difference records the history of the formation and evolution of the crust. Deep structural setting for the Ms≥7.0 strong earthquakes in this region is also discussed.
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大地测量与地球动力学. 2003, 23(S1): 41-49. https://doi.org/10.14075/j.jgg.2003.s1.008Global Positioning System (GPS) observations during four measurement campaigns from 1992 to 1999 are used in a study of the temporal and spatial variation characteristics of crustal deformation of active tectonic blocks in North China. The Euler vectors for these active blocks are determined on the basis of GPS velocities of a group relative stable points in 1992,1995,1996 and in 1996,1999 respectively. We have studied the relative motion between blocks at the boundaries and the intra block deformation field. We have also inverted the strain rate fields for these active blocks by bi cubic spline model based on the GPS velocity field. The results show that the intra block deformation rates are different from those in block boundary zones, and are also different in different periods; the deformational field is generally characterized by intra-block extension in North China.
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大地测量与地球动力学. 2003, 23(S1): 50-53,61. https://doi.org/10.14075/j.jgg.2003.s1.009The circum Pacific tectonic system that contains of convergent, divergent and transform boundaries, is the most active region of volcanoes and earthquakes in the world, and involves many important theoretical questions in geosciences. The relative motion and deformation of Pacific plate is still an active subject of research. In this note, we analyze the deformation of Pacific plate and obtain reliable results of the relative motion rates at the circum Pacific boundaries based on space geodetic data, which reveals the present day motion characteristics of Pacific plate.
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大地测量与地球动力学. 2003, 23(S1): 54-61. https://doi.org/10.14075/j.jgg.2003.s1.010A preliminary analysis of the time series of displacements at fiducial stations obtained from continuous GPS observations during the period of Sept. 1998 to Oct. 2001 in the Crustal Movement Observation Network of China (CMONOC) is made. The selection of datum for producing displacement time series suitable for earthquake prediction is discussed. Time series of horizontal crustal displacements are obtained by using a datum of a stable group of 9 stations with very small relative horizontal displacements in eastern China as reference. Time series of vertical crustal displacements are obtained by using a stable group of 7 stations scattered in different regions with relatively small relative vertical displacements as reference. During the period of 2000 to 2001, anomalous horizontal and vertical displacements occurred twice at the fiducial stations in western China. These anomalies may be related to seismic activities of magnitudes about 6 in the Yunnan region on the North South seismic belt.
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大地测量与地球动力学. 2003, 23(S1): 62-68. https://doi.org/10.14075/j.jgg.2003.s1.011On the basis of GPS observations in Yunnan from 1999 to 2001, we adopt the robust Bayesian least square estimation and multi fault dislocation model to analyze the quantitative kinematics models of the main faults in Yunnan. The geodetic inversion suggests that: (1) The horizontal movement of crust in Yunnan is affected distinctly by fault activity whose characters are consistent with geological results; (2) The activity of the north segment of the Red River fault zone is maximum, in the middle segment is moderate, and in the south segment is minimum; (3)Among others, the Xiaojiang fault zone has the strongest activity, the secondary are the Lancang fault zone and the north segment of Nujiang fault zone, the Qujiang fault zone shows the characteristic of hinge fault; (4)Each fault could produce an earthquake of Ms=6 more or less per year; (5) The larger value of maximum shear strain are mostly located along the main active fault zones and their intersections; earthquakes did not occur at the place of maximum shear strain, and mostly take place at the higher gradient zones, especially at its corner.
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大地测量与地球动力学. 2003, 23(S1): 69-73,82. https://doi.org/10.14075/j.jgg.2003.s1.012On ths basis of interaction between faults, a finite element model for Southwest China is constructed,and the stress adjustment due to the strong earthquake occurrence in this region was studied. The preliminary results show that many strong earthquakes occurred in the area of increased stress in the model. Though the results are preliminary, the quasi-3D finite element model is meaningful for strong earthquake prediction.
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大地测量与地球动力学. 2003, 23(S1): 74-78. https://doi.org/10.14075/j.jgg.2003.s1.013This paper discusses the regularization solution of ill-posed equation with the help of its spectral decomposition formula. It shows that regularization can filter the influence of the high frequency errors which are very sensitive to the parameters to be estimated, and gives a complete derivation of the spectral decomposition formulae of least squares adjustment, rank deficient adjustment and the regularization solution of ill-posed equation. It also shows the equivalence between the trace of the mean squares error and the expectation of the secondnorm of estimated parameter's total error.
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大地测量与地球动力学. 2003, 23(S1): 79-82. https://doi.org/10.14075/j.jgg.2003.s1.014Continuous Rapid Deformation (CRD) may be an important precursor before some strong earthquakes with magnitude greater than Ms5.0. This paper shows some characteristics of CRD, and proposes a method for identifying precursory CRD that is closely related to the process of earthquake preparation. From the deformation data in Yunnan Sichan provinces, we obtained the tilt and strain thresholds of 4.5ms/d and 5 ×10-7 /d, respectively. Compared the tilt CRD in this region before 9 earthquakes (short term fore shocks and after shocks not included) with magnitude greater than 5.8 in the period from January of 1990 to May of 2001, we found that 8 earthquakes occurred within 5 months after the CRD with a duration of more than 20 days and a tilt velocity of more than 4.5ms/d without false prediction, but with one failure in earthquake prediction. For the strain CRD, 5 earthquakes occurred after the CRD; there was no false prediction, but 4 earthquakes unpredicted. We have tried to increase the thresholds, but found either the failure ratio or the rate of false prediction increased, while the success rate not obvious increased.
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大地测量与地球动力学. 2003, 23(S1): 83-88. https://doi.org/10.14075/j.jgg.2003.s1.015The co seismic and post seismic deformation velocities of Ms 8.1 Kunlunshan earthquake on Nov. 14, 2001 were calculated from the results of 1991-2001 GPS data and 4 repeated GPS surveys after the event. The result indicates the maximum co seismic and post seismic changes are 1.9 m and 0.08 m respectively. On the basis of the result of post seismic velocity, we used an elastic dislocation model to inverse the crustal deformation characteristics of eastern Kunlun active fault. The result shows that the domain motion of eastern Kunlun fault is left lateral and strike slip. The trend of eastward motion for the southern block of Kunlun fault implies redistribution and reaccumulation of energy after the earthquake. It is possible that the seismicity will migrate to eastern region in the future according to the trend that strong earthquakes along Kunlun fault extended from west to east during the last several decades.
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大地测量与地球动力学. 2003, 23(S1): 89-93,107. https://doi.org/10.14075/j.jgg.2003.s1.016GPS observations of CMONOC and other network reveal that, relative to Dingxin fiducial station in Alashan block, the crustal movements of north eastern Qinghai Tibet plateau and its adjacent regions have the following characteristics:(i)The western part of Qilian block is shortening and moving mainly northeastward, the 8 mm/a motion of southern margin of Qaidam basin is almost completely absorbed by compressed subsidence of Qaidam basin and uplift of Qilian mountain; (ii) Eastern part of Qilian block manifests itself mainly as block like rotation or extrusion along Haiyuan left lateral fault,with an angular velocity of 0.135 /Ma; (iii) Due to the clockwise rotation of the eastern Qilian sub block in the NW Liupanshan range, Ordos block shows a slight anticlockwise rotation; (iv) Haiyuan left lateral fault and northern edge thrust fault of Qilian mountain jointly constitute the major northeastern boundary of Qinghai Tibet plateau judging from the present day crustal movement.
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大地测量与地球动力学. 2003, 23(S1): 94-100. https://doi.org/10.14075/j.jgg.2003.s1.017By processing and analyzing geodetic data of vertical deformation, fault deformation and horizontal deformation by GPS in Gansu Ningxia Qinghai area and by comparing them with geological structures and many medium to strong earthquake activities in this area, some features of recent tectonic deformation anomaly and the development of medium to strong earthquakes are studied. The results show that: ①Near the main faults tectonic deformations are relatively large. The amount of vertical movement and the deformation status evolve with time. The horizontal movement and deformation show obvious compressional strike slip character. ②The dominant stress of tectonic deformation and seismic development in this area comes from the persistent northeastward compression of Qinghai Tibet block;The time spatial distribution evolution of tectonic deformation and seismic activities are closely related to dynamic evolution of block motion and regional tectonic stress field. ③The abnormal uplift and high gradient deformation belts and remarkable fault deformation anormaly on the borders of regional tectonic blocks are indicators of developing moderate to strong earthquakes but earthquakes may not necessarily take place in the position of maxium deformation, it usually occurred in the region where fault deformation anormaly shows “trend accumulation acceleration turn ” variation character or nearby. On the basis of above study, a preliminary prediction for strong earthquake risk in this area is given.
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大地测量与地球动力学. 2003, 23(S1): 101-107. https://doi.org/10.14075/j.jgg.2003.s1.018Deformation measurements such as short range leveling, short baseline, continuous cross fault strain measurement are carried out at different intervals from 1982 to 2001.All these measurement sites are built across the boundary tectonic belts of Yunnan Sichuan block. On the basis of these deformation data, the annual deformation rates at all sites are calculated and their change curves with time are plotted respectively. With these calculated results, we analyze the vertical and horizontal movements of tectonic belts of Yunnan Sichuan block, and the relationship to grouped strong earthquakes occurred in the block are discussed as well. These results show that the tectonic activities in the western and southeastern Yunnan are intensive. Along some eastern boundary belts: from Qujiang, Xiaojiang fault belts in the south of Yunnan to Xianshuihe fault belts in northwestern Sichuan, present annual rate of horizontal deformation decreases.Along Xianshuihe, Xiaojiang and Longmenshan fault belts the rates of vertical deformation change are small,but the vertical deformation change rates along Anninghe and Zemuhe fault belts are comparatively large. The comprehensive analysis shows that grouped strong earthquakes will occur probably when the deformation rate changes sharply. Thus we think that sharp changes of deformation rates may be one of the seismic precursors.
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大地测量与地球动力学. 2003, 23(S1): 108-113. https://doi.org/10.14075/j.jgg.2003.s1.019Thermal stress in meteoroids by aerodynamic heating is calculated for the ideal case of an isotropic,homogeneous,elastic sphere being heated at the surface with a constant heat transfer coefficient.Given enough time,the tensile stress in the interior of the meteoroid can be as high as 10 kb.This stress value is greater than estimated tensile strengths of meteoroids and the aerodynamic compression they encounter.Significant thermal stress(1 kb) can develop quickly(within a few tens of seconds) in a small(radius<10 cm) stony meteoroid and a somewhat large(radius<1 m)metallic meteoroid,and thus may cause tensile fracture to initiate in the meteotoid's interior.Fracture by thermal stress may have contributed to such observations as the existence of dust particles in upper atmosphere,the breakup of meteoroids at relatively low altitudes,the angular shape of meteorites and their wide scattering in a strewn field,and the explosive features of impact craters.In large meteoroids that require longer heating for thermal stress to fully develop,its effect is probably insignificant.The calculated stress values may be upper limits for real meteoroids which suffer melting and ablation at the surface.
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大地测量与地球动力学. 2003, 23(S1): 114-118. https://doi.org/10.14075/j.jgg.2003.s1.020In this work, the authors present some results of strain monitoring within the territory of Vietnam from 1984 to 2001. Data analysis shows that (1) the Phu Lien area is tectonically stable with low strain rate, 1×10-6 /a; (2) the Hoa Binh area has indication of tectonic instability with relatively high strain rate of the earth crust: absolute value of the strain reaching 100×10-6, usual average strain amplitude of 60×10-6, whereas the monthly average strain intensity varies in a range from 30×10-6 to 50×10-6; (3) there are clear indications of the strain state of the earth crust before occurrence of earthquakes of medium or higher magnitude. This is a very important indication in the research and short term prediction of earthquakes, especially for the areas with low seismic stability like the NW of Vietnam.
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大地测量与地球动力学. 2003, 23(S1): 119-126. https://doi.org/10.14075/j.jgg.2003.s1.021Stratigraphy, the basis of geological dating was founded in the ⅩⅦ century on the three well known principles assumed by Stenon: superposition, continuity, original horizontality. These three principles came from a postulate in sedimentology: layers of sub soil are strata of ancient successive sediments. Stratigraphy is, therefore,based upon data acquired from sedimentology.On the basis of successive observations and experiments this paper realises and verifies that Stenon's stratigraphic model was not in line with experimental data because it had “overlooked” the major variable factor of sedimentology: the current and its chronological effects. The sedimentological process can, effectively, be divided into three phases: erosion, transport and deposit of sediments,with the liquid current being the vector of transport. Stenon's stratigraphy only took into account the third phase of sedimentology, the deposit, implicitly assuming the velocity of current to be nil. The author of this paper simulated the constitution of layers of sediment generated at variable velocities from differing granulometries.He reincorporated the chronology of currents into the field of his scientific investigations, as it was indispensable for modelling all the interlinked sequences in sedimentology, stratigraphy and geological dating.The author introduced paleohydraulics as the new approach to geological dating to integrate the two ends of the chain,and refers to radiometric dating measures of eruptive rocks recognised as aberrant in relation to the date of eruption.Generally speaking,the new approach paleohydraulics brings about the establishment of experimental sedimentology and Stenon's ⅩⅦ century postulate and principles are no more than interpretations that must be carefully checked with data from observation and the laboratory.
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