13 December 2013, Volume 33 Issue 6
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jgg. 2013, 33(6): 1-4.
Gravity gradient is the main physical parameters in gravity measurements，6 components of the gravity gradient contain more information about the earth than usual gravity measurement. The co-seismic space distribution and temporal variation of the gravity gradient are analized acooeding to the results computed with 112 periods GRACE observed during Jan.,2003 and Jan.,2012 for the area of Japan 9.0 earthquake，based on the spherical function formulas of the 6 components of the gravity gradient in earth fixed coordinate. The theory and methods to eliminate singularity of the spherical function formulas of the 6 components of the gravity gradient are discussed. The results show that the component Tλλ,Trr,Tθλ of gravity gradients are consistent with the tectonics in the area. Temporal variation of the 6 components of the gravity gradient in about 1 year before the earthquake appeared anomaly，and the coseismic variation of the 6 components of the gravity gradient are also obvious.
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jgg. 2013, 33(6): 5-9.
Discrimination between post-seismic effect and earthquake precursor of vertical deformation after large earthquake was analyzed with the regional leveling and fault-crossing leveling data before and after Ms 8.1 earthquake in Qinghai-Xinjiang area and Wenchuan Ms8.0 earthquake in the northeast margin of Qinghai-Tibet.The results show that: Post-seismic effect was reflected by counterinheritance motion of mountain decreased and basin uplift，it indicates that the tectonic stress field “weak compressing” or “relaxation” before big earthquake；And earthquake precursor of vertical deformation was reflected by inheritance motion of ascending and descending differently，it indicates an intensive trend of tectonic stress field before big earthquake.
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jgg. 2013, 33(6): 10-15.
An evolution of activity of main faults in Western Yunnan is inversed by use of the genetic algorithms with the repeat gravity datum from 1985 to 2010 based on the original fault model and consideration for crust layering,viscosity and gravitational effect. The results indicate that the faults have characteristics of reciprocating motion, and reflect well preparation process of earthquakes greater than Ms6.0. There are difference and consistency between the tectonic movement of shallow and deep part of Red River Fault Zone, which regulate the conversion relation by strong earthquake preparation and occurrence. The movement of the faults can be divided into several steps: speed up, speed up to peak value, speeddown, speed up again, speeddown again. Earthquakes occur on the last step.
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jgg. 2013, 33(6): 16-19.
Based on the data of precise leveling survey in 2001、2005 and 2009 around the Capital Circle area，the elevation variation induced by subsidence at the mobile gravity measuring points were calculated for the data from 2001 to 2009 in this area. With Bonguer correction formula of high precision, the gravity variation induced by subsidence at the mobile gravity measuring points from 2001—2009 in Capital Circle area were obtained from the varied elevations at the points. The results show that, the gravity variation induced by subcidence at the mobile gravity measuring points can be calculated accurately with precise leveling data.
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jgg. 2013, 33(6): 20-23.
Observation data of mobile gravity in Guanzhong region in recent 20 years are reprocessed by using quasistable adjustment method, and combing with other observation data and research results, the variation process of regional gravity field, gravity field variation characteristics before and after three medium and small earthquakes, tectonic activity and earthquake relations are analyzed profoundly.
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jgg. 2013, 33(6): 24-27.
The average acceleration approach does not require any initial information of unknown parameters, and does not need interpolation or differential of orbits, which is more rigorous than pointwise acceleration approach. The parameters of the residual acceleration are unified to solve with coefficients when gravity field modeling by using the average acceleration approach. A gravity field model, which named GOCEAAA01S, is recovered based on GOCE precision orbits of days from 20091101 to 20100131 with the average acceleration approach. The results show that the gravity field model with the best accuracy is recovered by 12order polynomial and the accuracy of the recovered gravity field model will reduced when the order increases or decreases of polynomial. The geoid error of the model GOCEAAA01S is ±6.8 cm with 120order, the accuracy of the model GOCEAAA01S is higher than the model EIGENCHAMP05S with 6 to 120 order, but lower than the model EGM96 with the order over 102, and the precision of zonal coefficients is low due to the polar gap.
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jgg. 2013, 33(6): 28-30.
A fast algorithm was presented in the paper. Classical spherical approximation formula is able to be used to calculate model gravity anomaly by computers; however，the speed of calculation is still away from demand. So，a new formula is needed to improve operating speed. Throuph spreading Taylor formula，getting access to zeroorder term，oneorder term and twoorder term respectively，and comparing speed and accuracy of three methods’ speed and their accuracy，an optimum practical algorithm for calculating model gravity anomalies is obtained.
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jgg. 2013, 33(6): 31-35.
A new method which could obtain the crustal horizontal strain and fault deformation from crossfault data is proposed. Using the crossfault baseline and leveling data at Tangshan seismostation during 1999 to 2012, the vertical deformation of the Tangshan fault is calculated with a presumption that the fault vertical activity is rigid body movement. And then assuming that the fault zone and its surrounding areas are uniform strain fields, the fault horizontal movement and the strain characteristics of the fault zone from the crossfault baseline data are separated, then the horizontal and vertical activity rate of the Tangshan fault, the strain characteristics and principal stress direction of the fault zone are solved.
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jgg. 2013, 33(6): 36-40.
Using the gravity data of the Riwoqe-Yushu-Maduo profile, undulations of density interfaces, normalized full gradient and gravity isostasy were analyzed to detect geodynamic background of Yushu Ms7.1 earthquake. The results show that: The crustal thickness in Qiangtang block is greater than that in Bayan Har block; The larger scale abnormal body with lower density locates in lower crust in Qiangtang block, and abnormal body with lower density locates under the bottom surface of the upper crust in Qingshuihe area of Bayan Har block; The isostatic state in Qiangtang block differs from that in Bayan Har block significantly.
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jgg. 2013, 33(6): 41-44.
In order to investigate geometry shape and activity of Luhuatai Fault Zone which locates in the northwest Yinchuan Basin，a 3D seismic exploration was completed whin an area of 550 m×875 m.The results show that it is a buried active fault zone and consisted of two faults，main fault F1 and secondary fault F2.The fault zone moved untill the late stage of Middle Pleistocene. Trend of F1 is SE，and F2 is NW，both of them are normal faults. The activity time of F1 is newer than that of F2，and the fault throw of F1 is larger than that of F2. The buried deepth of the upbreakpoint of F1 has a trend of increasing from North to South. The distance between F1 and F2 increases gradually from North to South on the horisontal plane，reduces gradually with depth increase on the vertical profile，and F2 merges into F1 at the depth of about
780-800 m. -
jgg. 2013, 33(6): 45-48.
The vertical deformation rates in Tianjin area was calculated from standard data of repetition measurement during 20052012,and the interference of settlement of each line was excluded to enhance the information of crustal movement. The recent motion of block and recent activity of fault were studied based on the results in the area. The results showed that the overall trend of vertical deformation were to rise at northern part and to fall at southern part in Tianjin. There were differences in movement of the blocks. Some tilted, some overall rose, and some pleated. The recent activity rate of main faults in Tianjin Area was in 0.251.16 mm/a.Most of faults activity were inverse, and a few normal.
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jgg. 2013, 33(6): 49-52.
The relatively stable reference point or benchmarkand was finded according to the concept of “relatively stable” and it was used to analize stability of the leveling points and evolution of the motion state with the data from the Capital Circle Vertical Deformation Monitoring Network and the Control Land Subsidence Monitoring Network in Tianjin.The results combined with the analysis results of GPS data indicate that Liqizhuang bedrock point is sinking at 2.5 mm/a in the recent years.
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jgg. 2013, 33(6): 53-56.
Main paramrters，such as MP1，MP2，CSR and effective rate of the data from July 2011 to September 2012, got from 76 stations in Hubei CORS were evoluted using TEQC. The results indicate that quality of the data of 99.4% is better than the quota of IGS.Ｔhat means that the data can satisfy the requirements in the study on surveying，mapping，meteorology，seismology and so on.
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jgg. 2013, 33(6): 57-61.
The elevation of the Ⅲ terrace(T3) surface of the Yongjiang river around the Nanning basin was analyzed with the Sufur software. According to deformation characteristics, the terraces can be divided into subsidence terraces and erosion terraces. Based on this, a conclusion can be drawn that the deformation of the terrace is because of activation of mantle plume thermal fluid. In the Cenozoic Time, the mantle plume thermal fluid under the Brain upwells and flows eastward, which lead to upper crust getting thinner and creeping eastward with extension, both cause the terrace deforming as an anticline.
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jgg. 2013, 33(6): 62-67.
The Eastern Dabie Mountain area is a typical faultblock structure, for it is cut by NWW and NE trending faults and consists of four tectonic belts, i.e. North Huaiyang Belt, Dabie Belt, Zhangbaling Belt and Northern Yangtze Craton Tectonic Belt. It can be divided into four levels of planation surfaces from higher to lower: the Top Surface or the Unifying Top Surface, the Piedmont Surface or Joint Piedmont Surface, the Erosion Surface，and the Peneplain to Etching Plains, named as Tiantangzhai Surface, Dabie Surface, Huainan Surface and Jianghuai Surface respectively. The corresponding geomorphologic cycles are called as Tiantangzhai Physiographic Stage, Dabie Physiographic Stage, Huainan Physiographic Stage and Jianghuai Physiographic Stage. All these planation surfaces are transformed or deformed by vertical and horizontal displacement, gently fold or faulted at different degrees since the formation，which closely related to the activities of NWW and NE trending faults since the late cretaceous.
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jgg. 2013, 33(6): 68-71.
This paper introduces Lipschitz index to describe the singularity of superconducting gravimeter(SG) data. According to the relationship between wavelet transform modulus and Lipschitz index, we detect the singular value location via tracking the multiscale wavelet transform modulus maxima of the singular value. Utilizing wavelet decomposition and reconstruction, the singular value is eliminated and separated. Then, the simulated and measured data are processed and analyzed. The results confirm that the wavelet can detect and separate the singular values from the SG records effectively.
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jgg. 2013, 33(6): 72-77.
A new method for recognition and classification of appropriate background area, base on SVM, is presented.The method can be used to solve false matching problem in terrain matching navigation. Firstly, the relationship between statistical parameters and the precision of matching are established according to the statistical parameters with higher significance got from statistics of background area. Secondly, the statistical parameters mentioned above are input to train the network with SVM. Trial results prove that the method is the feasible and efficient.
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jgg. 2013, 33(6): 78-80.
The simultaneous adjustment method of gravity gradient had been improved, and the gravity difference between the high point and the low point, the system difference of reading and the difference of drift corrections between the two relative gravimeters can be calculated. The validity and applicability of the above method had been proved by comparing the results of example’s calculation and data processing model.
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jgg. 2013, 33(6): 81-85.
Using the nonlinear fitting method based on oval standard equation method, we improves the old method used for obtaining the dip angles of underground steps or fault structure based on quadratic curve equation operated with a least squares way in fitting gzgx gradient space diagram. And then, after comparing groups of experiment calculation of 2D steps and fault dips with different geometrical parameters, the stability and accuracy of the method are verified.
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jgg. 2013, 33(6): 86-89.
Importance of observation’s error in seismic inversion was discussed,and the seismic wave simulation data that contains error were inversed using methods of LSQR, WLSQR and MLS. The inversion results show that the effect of observation’s error is notable in seismic surface wave inversion ,and ignoring the observation’s error will greatly reduce the reliability of inversion results.
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jgg. 2013, 33(6): 90-93.
In the high precision network RTK positioning process, the large atmospheric delay interpolation error will be caused by the elevation difference between the user station and the reference station network which would affect its normal positioning. By analyzing the conventional linear interpolation model, an improved linear interpolation model is presented. The improved model, for calculating troposphere double difference delay error correction accuracy between the user station and the main reference station pairs using the US CORS data, has increased about 1 to 2 cm.
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jgg. 2013, 33(6): 94-97.
This paper carried out different levels of combined simulations of COMPASS, GPS and GLONASS systems based on the STK software, and analyzed the data of the visible satellites number, PDOP value and the positioning accuracy in China region. Simulation results indicate that: with the given UERE value of the various systems in the Standard Positioning Service, the positioning accuracy of the combination of three systems is 56 m, and PDOP value is 0.8~0.9, which is better than the combination of dual systems, while the combination of dual systems is superior to the single system. Meanwhile, the results also show that the PDOP value in combination of three systems is lower and the positioning accuracy is higher, and the fluctuations are more gentle.
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jgg. 2013, 33(6): 98-102.
An Adaptive Unscented Kalman Filter (AUKF) model using Innovation-based Adaptive Estimation (IAE) is implemented. A 21state filter using tightly coupled integration scheme is employed on the GNSS/INS simulation platform，several test schemes are designed based on different filter models, the result shows that the AUKF model can restrain the influence of the state estimation errors for adaptive estimation, and reduce abnormal errors, the accuracy and reliability of navigation system are improved obviously, and it has no negative impact on the efficiency. The positioning precision of multimode satellites systems increases by 49.38%.
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jgg. 2013, 33(6): 103-106.
According to the features of three frequencies linear combination observations values of optimized GLONASS, three linear independently combinations are selected to simulate carrier phase observations, and a detecting cycle slip model is established using threefrequency combination observations combined with pseudorange. Experiments show that the ability to detect and repair cycle slip of GLONASS carrier phase can be improved.
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jgg. 2013, 33(6): 107-111.
According to the data structure of JPL’s Development Ephemeris (DE) series, a simplified method is presented to facilitate the computation of autonomous orbit determination onboard GNSS satellite. The storage size of DE406 ephemeris in a period of 20 years is reduced to 369kb with this method. This simplified DE406 is verified with an experiment of longterm orbit integration of GPS satellites. The results show that the maximum prediction error in the normal direction is less than 3.0 meters during 60 days. This simplified method could not only ensure the accuracy and computational efficiency of autonomous orbit determination algorithm, but also decrease the data storage space onboard GNSS satellite.
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jgg. 2013, 33(6): 112-114.
An iterative algorithm for the simple linear regression based on theory of Lagrange was presented. It is easy to deduce and productive using the algorithm. Numerical examples prove the algorithm is accurate.
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jgg. 2013, 33(6): 115-120.
To study the temporal and spatial variations of Ionospheric Electron Density (IED), the profile distribution of IED over Sichuan during the geomagnetic quiet are inversed by using GPS observation data from Crustal Movement Observation Network of China (CMONOC）and ionospheric tomography technique. The results show that the diurnal variations of IED are obvious at various latitude and altitude. The maximum value of IED appears at 06:00UT. As time goes on, the value of IED gradually decreases and achieves the minimum at 22:00UT. E layer appears in the daytime and disappears in the night. The study demonstrates that the ionospheric tomography (CIT）technique can be used to efficiently monitor temporal and spatial variation of ionospheric structures.
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jgg. 2013, 33(6): 121-125.
A new method of normal μ hypothesis testing was proposed, which can detect and remove the abnormal stations automatically. Through statistical testing and iterative adjustment, the stable stations for the rigid plate were confirmed. The rigid stations in global 9 plates were qualified successfully using the method and the global plate motion model based on ITRF2005VEL was constructed. The result shows that the construction model agrees well with other models as a whole and the precision is higher.
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jgg. 2013, 33(6): 126-129.
The main factors that affect precision of strain tensor calculation by a triangular unit are triangular shape and its orientation in the coordinate system. This paper introduces the condition number of coefficient matrix and discusses its relationship with precision of strain components. The results show that the threshold value of condition number for strain tensor calculation is 4.3 so as to keep that the precision of strain components and displacement data is in same level.
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jgg. 2013, 33(6): 130-132.
Using the geometric relationship among NEU coordinate system obtained with the GLOBK software, Cartesian coordinate system (XYZ) and ellipsoidal coordinate system (BLH), taking into account the threedimensional velocity transformation parameters between various ITRFs, a direct conversion formula of crustal horizontal velocity with various ITRFs is derived. This transformation process is clear and easy to be programmed. The result demonstrates that there exists a significant systematic bias in the horizontal movement velocity field within the ITRF2005 and ITRF2008.
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jgg. 2013, 33(6): 133-136.
On the basis of Singular Value Decomposition (SVD) theory and analyzing TSVD method, a new technique for amending singular values based on the multicollineary diagnosis is proposed. The numerical results show that the proposed method can resist the illconditioned effect and improve the stability and accuracy of parameter estimation.
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jgg. 2013, 33(6): 137-140.
on objects was presented. Firstly, typical objects are determined as reference objects by field mapping and visual interpretation.Then the assessment function and the optimal segmentation scale can be obtained through caliculating the gray similarity and the shape similarity between reference and segmentation objects. The validity and applicability of the method is verified by practical treatment of World View2 multispectral images based on this assessment function.
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jgg. 2013, 33(6): 141-144.
A new model for estimation of zenith tropospheric delays by regional CORS data without any meteorological data was presented，based on the investigation of the relationship between tropospheric delay and the elevation and longitude. Then the accuracies of new model are compared with the direct interpolation method and removerestore method by using the data from Guangxi CORS，respectively. Research results show a significant improvement for the calculated precision with the new model.
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jgg. 2013, 33(6): 145-149.
A method extracting optimal index from desert index，normalized differential desert index，and modified soiladjust desert index was presented. The method is obtained by band math，based on the obvious differences between absorption and reflection of desert. The results of analysis with the TM image of Shanshan Kumu Tage in 1995，2000，2005 and 2010 using the optimal index indicate that the method is feasible.
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jgg. 2013, 33(6): 150-154.
On the basis of the time series analysis model, higher difference, gray model, spectrum analysis and singular spectrum analysis method are used to extract nonstationary time series trend, and model smooth residuals for time series. The analysis results of dam displacement monitoring series indicate that prediction accuracy is improved by using singular spectrum analysis and spectrum analysis of time series analysis model compared to the traditional model of higher difference timing analysis model and gray prediction model.
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jgg. 2013, 33(6): 155-159.
A projectionextension method to calculate zenith tropospheric delay(ZTD）of mobile stations was presented. The method is based on the inverse distance weighted fomular derived from Taylor series expansion，and the high order terms were considered. The interpolating accuracy can be improved with the method for the stations located at extremely high elevations. Operation of the method is to project elevation of a station to the mean elevation plane，and to calculate the ZTD of the projection point with the method，then extend it to the actual position using polynomial fitting. An experiment results is done with the GPS data of SCIGN，and the results show that the interpolation method based on higher Taylor series expansion has better performance in calculating ZTD of rover stations than IDW，especially for stations with high elevations. Combined with projectionextension method，it can also get ZTD of rover stations which have extremely high elevation at millimeterlevel accuracy.
