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01 July 2011, Volume 31 Issue 3
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. 2011, 31(3): 1-7.On the basis of cubic spline function and stack InSAR,we used the GPS data of more than 10 years and over 200 SAR images from 2003 to 2007 to calculate the 3D velocity diagram in the area including Kashi depression and the border region of Pamir and the south Tianshan.
There is an obvious boundary feature for the vertical changes in Kashi depression where its north boundary is the south Atushi fault, its sorthwest boundary is the Wupar fault and its east boundary is the Tarim basin. The vertical changes within the interior of Kashi depression is featured by subsidence at 1mm/a, while the peripheral region is featured by uplift at 1mm/a and decreasing from east to west. The front boundary between the basement of Tarim basin, the south Tianshan and the Pamir Plateau are south Autshi fault and Wupar fault. The vertical change of Keping nappe is characteristiced by its tectonics structure. The fold belts uplift and the vally area subside at a rate about 1--1.5 mm/a. Although the Puchang fault crosscuts the Keping nappe, there are not obvious vertical changes in both sides revealed from profiles across the fault. The lateral changes of the shorten rate of Tianshan across Puchang fault from GPS are evident, which indicates that the Puchang fault is a quasi transform fault dominated by strike slip. -
NUMERICALLY MODELING THE INFLUENCE OF RHEOLOGICALPROPERTIES ON TECTONIC DEFORMATION OF TIBET PLATEAU. 2011, 31(3): 8-14.In order to analyze the effects of the rheological properties against the contemporary tectonic deformation of the Tibet plateau,
we carries out numerical simulation by building up a 3D finite element viscoelastic model which use the standard linear solid model’s constitutive relation. The results show following characteristics.1) Under the control of rheological mechanism
of crustal medium, the eastward displacement components become bigger and bigger from west to east in the Tibet plateau. The maximum appears in the region south to GanziYushuXianshuihe faults, it implies that the mass under the Tibet plateau flow eastward. 2) The model simulated contemporary tectonic movement characteristics in this region which show that in the middle and south part of the rhombus block,
the southwest parts of SichuanYunnan region clockwise rotate around the Himalaya eastern tectonic joint.
The crust moves southeastward in the east while southwestward in the west. 3) The results of two models with stronger rheological property in middle crust and in lower crust respectively have similar characteristics: both can model the eastward flow in plateau and clockwise rotation around the eastern Himalayan syntax. 4) The rheological properties play an important role in the tectonic deformation of Tibet plateau. -
. 2011, 31(3): 15-19.On the basis of the GPS data of Chinese Crustal Motion Network in North China, the velocities and the strain rates on blocks in North China were calculated, as well as these on block’s boundary fault zones.
The North China subplates’ motion and features of the strain rate, and also the features of the strain stress of the block’s boundary fault zones were studied. The results show that the direction of the westeast movement field of North China subplates turns from east to southeast, the NENNE fault zone is of rightlateral strike slip activity and the NWWEW fault zone is of leftlateral strike slip activity. The directions of the principal compressive strain axis of the subblocks are different. The present strain of the block’s boundary fault zones indicates that the force of the north part of Tanlu fault zone and the Shanxi downfaulted zone is mainly compressive, the strain energy is accumulating,
but the strain rate is small, the speed of the accumulation is slow, so we should pay attention to the variation in future. -
. 2011, 31(3): 20-24.By using threedimension nonlinear dynamic finite method and GPS velocity fields in two time periods,the late tectonic deformation features of HaiyuanLiupanshan arc fault and its Surrounding Area were studied. The following results are obtained.1) HaiyuanLiupanshan fault is of left lateral slip in whole but they are different in the two sections that the left lateral slip rate of Haiyuan fault is 2-5.5 mm/a and Liupanshan fault about 1.0 mm/a. 2) At present, the junction segment of Haiyuan fault with Liupanshan fault is in strong locking state, where the moving deformation difference is relatively strong and strain engery accumulate rapidly. As a result, the strong
seismogenic background may exist in this area. -
. 2011, 31(3): 25-28.The relation between vertical crustal movement and the gravity change was considered and simulated.
The gravity change was calculated with the digital elevation data and the velocity of vertical motion in the western China, was compared with the gravity change of the satellite observations. Results indicate that the characteristics of gravity change is highly relevant with the velocity of vertical motion.The Himalaya Mountain has the greatest positive value of gravity change in the south of the QinghaiTibet Plateau, because it has the greatest positive velocity of vertical motion. The Junggar Basin has the greatest negative value of gravity change, because it has
velocity of the greatest negative value of vertical motion. The Tarim Basin and Qaidam Basin have velocity of smaller negative value of vertical motion than The Jungar Basin’s, so they have gravity change of smaller negative value too. -
. 2011, 31(3): 29-33.Using the data of GPS fiducial stations in China and IGS stations around the epicenter, we studied the horizontal microdynamic crustal deformations before and after Indonesia \%M\%w9.0 earthquake in far field. The E component showed regional distinction changes before the earthquake. It was that the stations located in northeast from the epicenter moved east, controlled by pinching action, whereas, stations located in northwest from the epicenter moved west ward, effected by stretching force. It showed a characteristic of harmony and consistency in a largescale space, corresponding better with the theoretical seismogenic patterns. Small but significant coseismic jumps are clearly detected by the stations which are more than 3 000 km far from the epicenter. The coseismic deformation vectors almost pointed towards the earthquake epicenter on the whole, reflecting the flocking impact of the diving slab towards overlaying plate on a farfield. And some of these sites change their dislocations obviously acted by the strong movement of earthquake fault after the earthquake.
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. 2011, 31(3): 34-37.According to the state specifications for the first and second order leveling(GB/T 129872006), the methods and formulae for several corrections including correction of leveling staff for temperature,
correction for normal nonparallel levels, correction for abnormal gravity, correction to solid tide and the load of sea tide,
are given, and the necessity of those corrections for analysis and calculation of crustal deformation in seismic study are discussed. The results of this work emphasize that doing corrections or not must be the same for the new leveling data and old one in crust deformation analysis and calculation. If the old leveling data are not corrected, it is not necessary to correct the new ones. Otherwise, more unreasonable results
may appear. For scientific research and multiple usage of leveling data, it is suggested that all the accessorial observation data in every leveling correction should be preserved completely in seismically leveling. -
. 2011, 31(3): 38-41.On the basis of crustal gravity isostasy theory,the theoretic isostatic crustal thickness(D) with Airy’s isostatic model in Hexi area was computed. In the same time, real crustal thickness(M) from the Bouguer gravity data was inverted,and then
compared these two thicknesses with each other
for researching crustal isostatic stability．The results indicate that the value D is generally larger than the value M and it means that the crust is in a monisostatic state. -
. 2011, 31(3): 42-46.The rates of Antarctic ice mass change have been estimated by use of the gravity solutions from GRACE level2 RL04 for the period of January 2003 to August 2008 released by UTCSR. Because C0 of GRACE is not accurate enough, C20 from Satellite Laser Ranging (SLR) is adopted instead. The decorrelation filter technique is used for the stripe shape signal presenting in the longitude direction. Antarctic ice mass change rates are investigated again when
the gravity in some one month has been chosen to get rid of, and the results are that the rates of Antarctic ice mass do not change a lot in the same area. Gravity model, filtering technique and ICE5G postglacial rebound model are combined to observe the ice loss in the west Amundsen Sea Embayment and the northern Antarctic Peninsula, the rates are -5.28±0.95 cm/a and -1.82±0.77cm/a respectively. Whereas ice mass rates in Southern Ronne Ice Shelf and Enderby land in east Antarctic are positive, and the rates are 1.42±0.69 cm/a and 1.43±0.72 cm/a respectively. Compared with the existing research results, the mass in the west Amundsen Sea Embayment is melting fast, whereas the mass rates in Southern Ronne Ice Shelf and Enderby land in east Antarctic change a little. -
. 2011, 31(3): 47-50.It has been verified by plentiful existing observations that the ionospheric disturbance do appear prior to earthquake.In this paper,on the basis of the ionospheric TEC derived from the GPS observation data from the reference stations of Crustal Movement Observational Network of China, we processed and analyzed the ionospheric TEC data prior to the WENCHUAN Ms8.0 earthquake by
Kalman filtering and then we compared the results with the previous conclusion,the results indicate that the establishment of the model of the Kalman filter is reasonable and reliable in the detection of the ionospheric TEC anomaly prior to earthquake effectively. -
. 2011, 31(3): 51-57.The implemented international Martian exploration programs including “Mars, Zond and Phobos1/2” in USSR, “Mariner, Viking, Mars Observer, Mars Global Surveyor, Mars Pathfinder, Mars Climate Orbiter, Mars Polar Lander, Mars Odyssey, Spirit, Opportunity, Mars Reconnaissance Orbiter and Phoenix” in USA, “Mars96” in Russia, “Hope” in Japan and “Mars Express” in Europe, and the future domestic and overseas Martian measurement missions are presented. The Martian gravitational field models produced by Martian observations are introduced amply,which including.1) the U.S.: 6×4, 6×6, 10×10, Mars50c, MGS75B, MGS75D/E, MGS85F/F2/H2, MGS95I/J, GMM1, GMM2B, GGM1025 and GGM1041C.2) the U.K.: 6×6.3) France: 18×18 and MGGM08A. The measuring principle and advantages in the SGGDopplerVLBI tracking mode are described,which will be applied in the future firststage China’s Martian satellite gravity measurement. It is concluded that the electrostatic suspension gravity gradiometer is preferable in the future firststage Martian satellite gravity gradiometry mission in China by a comparison of strongpoints and shortcomings from electrostatic suspension, superconducting and quantum gravity gradiometers.
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. 2011, 31(3): 58-62.For the purpose of the research on the two current main methods of coordinate transformation, I expanded the Burse transformation model which was only fit for narrow angle to fit any angle transformation. Improved Burse transformation model of 7 parameters and 13 parameters transformation model are studied. Associating an example of the shield calculating the coordinate by the mean of three prism calculation, We did the comparison and drew a conclusion through the two sets of data including wideangle data and narrowangle data and programming.
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. 2011, 31(3): 63-68.The synchronous transformation method of GPS coordinate and height based on GPS control network threedimension constraint adjustment theory is given out.The steps of the method are as follows.At first, the baseline vector between two points is calculated from the threedimension rectangular coordinate of GPS points, and the rotation parameters, scale parameter and the coordinate parameters in
state coordinate system are also regarded as the unknown parameters, the coordinate and height transformation of GPS points are completed through the common points constraint. Finally,a case of GPS control network is used to test the method. The results show that the method is flexible, effective, and the transformation accuracy of coordinate and height are also well. -
. 2011, 31(3): 69-74.The instrument noise level is one of the most important factor for the evaluation of SG053. The tidal gravity residual time series of the SG053 has been analyised with maximum likelihood estimation (MLE) and three noise(white noise, flicker noise, walk noise) models and their combination.
It is shown that there is color noise in the tidal gravity residual,the white noise level is 1.40×10 -8 ms -2,the flicker noise 1.85×10 -8 ms -2 and the random walk noise 2.40×10 -8 ms -2. This analysis result is consistent with the tidal analysis. -
. 2011, 31(3): 75-78.The effect of tidal, peak, step, instrument drift and trend from the continuous tidal gravity data was removed by using the automatic extraction algorithm based on EMD and earthquake triggering algorithm, and achieved successfully the automatic extraction of tidal and nontidal gravitational information.
The examples show that the algorithm greatly reduces the manual work and it may be used for batch processing and quickly extracting the information of nontidal changes of a large number of stations. -
. 2011, 31(3): 79-84.Satellite gravity gradient data reduction and gridding are indispensable steps for recovering the Earth’s gravity field with spacewise method. The secondorder radial correction formula for gravity gradient data reduction is given, and the results show that the use of highprecision reference gravity field model can effectively reduce the reduction errors. The gridding accuracy and applicability of weighted average method, Shepard surface fitting and least squares collocation method are compared. As a test, the radial gravity gradient data that added with different types of noises are gridded with the above three gridding methods. The results show that the LSC method has obvious advantages compared with the weighted average and Shepard surface fitting methods, and it can be used for highaccuracy Earth’s gravity field recovery, so the LSC method is recommended for GOCE gravity gradient data gridded processing.
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. 2011, 31(3): 85-89.The results of combined GPS/GLONASS single point positioning (SPP) are compared with each other under different observation weights by using singlefrequency pseudorange observations and broadcast ephemeris data and then the effect of atmospheric errors on SPP is discussed and analyzed. Finally, the computation of SPP is conducted with the Least Square and Kalman filter algorithms. The results indicate that the combined GPS/GLONASS SPP can achieve accuracies better than 2.5 m in the horizontal components and 4.5 m in the vertical component for singleepoch solutions. In addition, accuracies better than 1 m in three coordinate components can be obtained during a 24hour observation period. Compared with GPSonly SPP, the accuracy improvement is significant for both algorithms.
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. 2011, 31(3): 90-93.On the basis of the influence of geomagnetic field on ionosphere, the position of geomagnetic north pole in geographic coordinates was estimated by using GPS signal and Klobuchar model, and the corresponding mathematical model was established. This method is validated to be feasible by theoretical analysis and simulated data, and it is further summarized that the regionalized improved Klobuchar model and perfect arithmetic will be in favor of the precision and reliability of estimating geomagnetic north pole.
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. 2011, 31(3): 94-97.An ambiguity groupsearching method is brought forward.At first,decomposing the ambiguities into two groups according to their variance can reduce the influence caused by the low precision floats and minimize the searching space efficiently. Moreover, a new verification by comparing the search output is used in ambiguity validation. The results of the experiments indicate that the new method can efficiently reduce searching space, increase searching speed and enhance the success rate of ambiguity resolution.
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. 2011, 31(3): 98-101.A preliminary study was carried out to analyze the pseudorange multipath effect from reference stations of Continuous Operation Reference System (CORS) in Hebei province from the following four aspects. 1)A comparison was made among the pseudoramge multioath effects under different cutoff elevation angles(5°, 15° and 25°)
and then the relations between the multipath effects and elevation angles are figured out.
2)All the reference stations are equipped with the same type of combinations of receiver and antenna, the discrepancy of the multipath can mainly due to the distinct environment of each receivers, taking several typical multipathaffected severely stations as examples, based on the basis of the skyplot of multipath, the effects of azimuth and elevationdependent effect of multipath were exactly examined, at meantime, a filed inspection of environment surrounding the stations was held, and the abovementioned factors further was verified.3)The dataset respectively from the strongest and weakest multipathaffected reference stations at the same day was processed, and the influences of multipath on the convergence time and repeatability of PPP solutions further were examined. -
. 2011, 31(3): 102-105.Interacting multiple model algorithm is proposed to control the influence of observation outliers in GPS/INS navigation. Redundant observations are not requested in this method. A multimodel set which includes both normal and exceptional observational models is established. The Markov transition probabilities are used to switch one model to another. When observations are normal, the normal observation model is used chiefly for the others the exceptional observation model works. Consequently, the algorithm can effectively control the influence of observation outliers in GPS/INS navigation.
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. 2011, 31(3): 106-109.The necessity of the shortterm prediction of polar motion and the current common prediction approach are discussed. ARIMA(P,1,0) is used in prediction of stochastic components in polar motion before,non a combinational model of least squares extrapolation and ARIMA(P,1,0) is given to forecast the polar motion from one to five day in the future. Through accuracy analysis, the efficiency and superiority of this model is proved.
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. 2011, 31(3): 110-114.On the basis of the total leastsquares(TLS) data processing theory and an iterative algorithm for TLS, firstorder partial derivative of the nonlinear model was determined by using Taylor formula and the error magnitude of the results was derivated. The method was applied to the TLS precision evaluation, and the method for reliability testing is proposed. The experimental results verify the feasibility of the method in TLS precision evaluation.
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. 2011, 31(3): 115-119.Through the analysis of the forced Earth’s surface and quasigeoid’ we found out that the traditional method for calculating the terrain correction may make errors.We explained the reasons for the formation of the error,derivated the formula, analyzed the source and size of its errors,and then put forward a new algorithm for calculation of terrain correcting.
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. 2011, 31(3): 120-123.On the basic of theory of PPP(Precise Point Positioning), we developed a program to calculate the ZTD, then we used the program and GAMIT to process the real observations.Compared the results with the data provided by the IGS, it is found that two methods both have high accuracy. Howver, the process results without faraway station data are of very low accuracy, it shows the advantage of Precise Point Positioning in the calculation of ZTD.
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. 2011, 31(3): 124-126.The air contains water vapor which has influences on air density. Therefore, when we correct the atmospheric loading effect of the gravity observations, we need to consider the influence of water vapor. Former researches did not analyze the influence of water vapor quantitatively. We construct a water vapor influence model and take Wuhan superconducting gravity observation for example, according to the radio sounding data in Wuhan district, calculate the influence of water vapor accurately. The result shows that the influence of water vapor to gravity observation can reach to 1.6×10 -8 ms -2, which means that the influence of water vapor on the precise gravity survey should not be ignored.
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. 2011, 31(3): 127-129.The threshold shrinkage denoising method based on lifting wavelet transform is expatiated. Besides，the method is used to filter the noise from single epoch GPS deformation monitoring data and get the real deformation information. The experimental data processing results show that the advantage of lifting wavelet transform lies on better denoising effect and consuming shorter time than traditional wavelet transform
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. 2011, 31(3): 130-133.
At present, there are various algorithms for producing the Minimum Convex Hull, but these algorithms consume relatively long computing time when the sum of spatial data points are more than
106. An improved algorithm which are of stability and efficiency is designed. Through scanning the data points one time, we can get two tables: Lateral Sorting Table and Longitudinal Sorting Table, and a Initial Minimum Convex Hull. After the scanning, we judge whether the current point can be classified in the Minimum Convex Hull based on Increase-point Method.
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. 2011, 31(3): 134-137.BP neural network technology improved according to LevenbergMarquart theory was used for GPS tropospheric delay prediction with the data of Southern California Integrated GPS Network. It is shown that the deviations between the predicted value of 76% GPS Stations and the actual value are less than 3cm. The accuracy of the prediction achieves centimeter level, at some sites amounted to millimeters. Unreasonabl spatial location of the site and site elevation different to the surrounding sites of training samples are the reason which leads to poor prediction for few sites.
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. 2011, 31(3): 138-141.In InSAR data processing, some residual linear phase trend still were left in the flattened interferogram due to the inaccuracy orbit parameters. In order to remove the effects of the residual linear phase trend on final InSAR results, a method to refine the instantaneous frequency estimation of InSAR interferogram and to remove the residual linear trend was introduced. First, the instantaneous frequency of interferogram is estimated with the accuracy of 0.1 fringes with the ChirpZ transform. Secondly, the linear trend is simulated from the instantaneous frequency and used to correct the InSAR interferogram. Finally,simulated and real data are used to test the method. The results show that the proposed method can completely remove the linear trend in INSAR interferogram and will help to improve the accuracy of InSAR greatly.
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. 2011, 31(3): 142-144.It is difficult to search the law of the dam’s deformation from a single point’s displacement. A new concept of displacementintensity is proposed,that is to study the distribution law of dam’s deformation,by use of the algorithm of decision tree for reference to building a model which includes data of all monitoring points at one direction.
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. 2011, 31(3): 145-149.Considering the unique superiority of airborne gravity survey, the application of gyrostabilized platform in airborne gravity survey system was researched. Firstly,the stable loop system of singleaxis gyro stabilized platform was established by using simulation module of matlabsimulink. Secondly, the mathematical module of correction circuit was established. Under the condition that we input limited parameters, simulation results were obtained.Thirdly, the horizontal error correction model for airborne gravity measurement was established and the horizontal error correction values were obtained.
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. 2011, 31(3): 150-155.In so much as the reality that the baseline measurement will be gradually falling into disuse, precise range measurement instead of baseline measurement is practically studied and tested. By means of the analysis of measurement error, the combination with the related equipment performance and its technical requirement, and on the basis of the study for theory, precise range measurements had been conducted numerously indoor and outdoor. In the meantime, its technical design is constantly modified, and its operational regulation is revised as well. As a result, the baseline measurement technique is updated and digitally remodified. The results of 6 years monitoring show that the updated baseline measurement technique is successful, the achievement is worth to be widely applied.
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. 2011, 31(3): 156-159.Distance between the image cell and its lightsensing area of linear CCD cannot be much small，so it has restricted application in high precision measurement system.
As the spatial information is able to be converted to the time information changing in one pulse unit by the design of interval precise delay driving pulse. It is proved that the limitation on accuracy of linear CCD image cell can be breakthrough effectively, and so the subpixel measuring can be achieved and detected by the displacement platform of high precise stepping motor.
