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12 April 2012, Volume 32 Issue 1
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. 2012, 32(1): 1-4.An accurate crustal deformation field was derived from repeat surveys of almost 90 GPS stations carried out from 1998 to 2011 in southern TianshanPamir region and present velocity field related to stable EuroAsia plate and the distribution of crustal horizontal strain field were obtained as well. We studied the active velocity along the main faults in the region and the following results are achived.1)The crustal shortening from south to north is the main movement trend in the southern TianshanPamir region. The movement of whole area shows the characteristics of clockwise rotation. 2)The amplitude of maximum principle compressive strain decreases from west to east in the southern Tianshan-Pamir region. The regional tectonics controls the space distribution of the strain field. It shows the features that the principal stress direction basically is orthogonal to the direction of the tectonic trend in the region. 3)There are close relation between the area of high shear strain and strong earthquakes. The maximum shear strain rate field concentrates mainly in the west of southern Tianshan, and the north area of Kalpin fault.
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. 2012, 32(1): 5-9.On the basis of World Stress Map(WSM) plan and GPS velocity field data we studied the stress orientation and strain rate in the Chinese mainland by using the least squlares collocation method.The results show that the two fields are consistent in general,but there are differences in
the east part of QinghaiTibet block,in which the orientation of stress is near NEword and that of strain raete is EW,and another difference region which locates in the west area of the Xiyu block whose stress orientation presents from NW to NE,with general direction is from west to east and the GPS principal compressive strain rate is mainly near NS. -
. 2012, 32(1): 10-12.
The gravity variations were computed in Indian earthquake region (76°~96°E,16°~36°N) with GRACE data
observed from July to September in 2009，2010 and 2011 respectively
taking the GRACE GGM03C gravity field model as a reference and then the monthly gravity variations of Indian mainland before and
after the Gaussian smoothing were compared between each other. The computed result is the most reasonable when the radius of the Gaussian smoothing is 600 km. The results show that the gravity variation of the studied area was positive in 2009. The gravity variation changed more than 4×10 -8 ms -2in New Delhi, Bhopal and Sikkim districts. In 2010,it was smaller than that in the same time,2009. The gravity variation change at the epicenter was of almost 6×10 -8 ms -2 in 2011 than that in 2009. The strong earthquake occurred within the steep gradient zone.
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. 2012, 32(1): 13-16.The historical earthquake catalogues（M≥4.5）and 1970—2010 earthquake catalogues（M≥1.0）in western Hubei and its surrounding areas are analyzed with the methods of physical fractal and R/S analysis. Accordingly,the natural cycle, fractal dimension and fractal scaleless range form every subset of small earthquakes are obtained,and the Hurst exponent (0.79) of
earthquake frequency sequences and Hurst exponent (0.87) of
earthquake timing interval sequences are obtained as well. Thereby the selfsimilarity and hierarchical structure of these earthquakes are revealed. -
. 2012, 32(1): 17-20.A spacetime datum which is a reference frame plays an important role in the study of regional gravity field variations. Because gravity values related with different spacetime datum will be different, whether the datum is reasonable or not,it has a crucial influence on the measured results of gravity variation. We study the characters of spacetime datum, estimate the advantages and disadvantages of applicability for the spacetime datum. We also give the standard for rational spacetime datum of regional gravity field, which could play a key role in valuing the results of gravity variation. The obtained results will effectively improve the quality of our previous results on gravity variation and lessen the difference between calculated modeling and real situation.
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. 2012, 32(1): 21-25.On the basis of geological survey of tectonic landform and drainage as well as fault feature to the middle segment of MachengTuanfeng fault belt, this paper involves its quaternary activity characteristic in seismology and geology and discusses on the tectonic deformation mechanism of the fault, combining the depth of earthquake source in study area. The preliminary analysis can be drawn from this study. The fault, which is characterized by normal faulting and rightlateral offset, is predominantly active in the middle Pleistocene and is weakening in the Late Pleistocene. The drainage offset is up to 2-3 km in the way of dextral motion. The host fault controls the branch fault and they share a sliping plane in the crust. The differential uplifting of crust and mantle depth, as well as regionally tectonic principal pressure stress field of NENEE orientation provide the fault motion with dynamic force source.
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. 2012, 32(1): 26-30.Global Positioning System (GPS) measure campaign in shear zone at lowlatitudes was conducted in 1991 and 2003, for quantifying the presentday major faults’ activity. The results are as follow,the north Antolia fault , Jiali fault, Sagaing fault and Sumatra fault are right lateral motion, the rates are（13.7±0.6），（5.8±0.5）（7.1±1.0），（12.7±0.2）and(25.4±0.5）mm/a respectively; while the Sorong fault and Guatemala fault are left lateral motion ,the rates are 29.2±1.8）,(14.1±1.0)mm/a， respectively . Besides, Sumatra fault and Jiali fault also show strong squeezing, (18.5±1.0), (15.2±0.6) mm / a， respectively, while Sorong fault show powerful pull, reached to : (10.7±1.1) mm / a. Overall, the shear activity dominats in the shear zone at lowlatitudes.
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. 2012, 32(1): 31-37.Integrating structural geology, geophysics, petrology and geochemistry and combining with seismic tomography data for the ancient remnants of the subducted lithosphere slab in the mantle，restoring the historical evolution of plate tectonics，we indepth have discussed the inner relevance between plate motion and mantle evolution processes of the Tianshan region
and mantle evolution，and try to explore new “W ConvectionDiving out” model to explain the complex dynamics of rock within the continental orogenic belt of Tianshan. -
. 2012, 32(1): 38-42.Taking central Wuhan as an example, on the basis of seismic damage prediction indexes with available methods, such as local general investigation, dividing the units from electronic map, and information from vector data, the calculation model of seismic damage index is amended from multiple scales and multiple angles,then the direct economic losses from destruction of the building can be estimated.
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. 2012, 32(1): 43-46.On the basis of the proposed approximate linear relation between the square of ocean depth and the gravity anomaly caused by the mass deficiency of the ocean water, the submarine topography of South China Sea was inversed by using the gridded gravity anomaly values from satellite altimetry data, and combing earth gravity field model EGM96 and ocean depth model ETOPE2. The inversion results are compared with the ship data and ETOPO2 model,it is shown that the accuracy and resolution
are significantly improved as compared to the ETOPO2 model. -
. 2012, 32(1): 47-50.The strategy used in the ITRF2008, the site distribution, ITRF2008 parameters accuracy and the improvement relative to ITRF2005 are introduced. IERS released ITRF2008 on May 31, 2010 and it is refined versions of the International Terrestrial Reference Frame based on four space geodetic techniques, VLBI, SLR, GPS and DORIS. The scale agreement between ITRF2008 and ITRF2005 solutions at epoch 2005.0 is estimated to be 1.05 ± 0.13 ppb and 0.049 ± 0.010 ppb/a respectively. The ITRF2008 orientation (at epoch 2005.0) and its rate are aligned to the ITRF2005. The differences of the origin components from ITRF2008 to ITRF2005 at epoch 2005.0 are: -0.5, -0.9 and -4.7 mm along the X, Y and Z axis respectively. The differences of Y and Z translation rate between these two frames are zero,the X translation rate is 0.3 mm/a. The formal error of these parameters are estimated to be 0.2 mm and 0.2 mm/a, respectively. The ITRF2008 origin accuracy over SLR observation period based on its agreement with ITRF2005 is considered to be less than 1 cm. ITRF2008 scale accuracy, considering the scale consistency between VLBI and SLR, within a common observation time span of two technologies is less than 1.2 ppb (8mm at the equator).
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. 2012, 32(1): 47-50.On the basis of the analysis of high sample rate of borehole strainmeter data and comparison with seismograph data，we
studied the characteristics of these datum.The results show that the TJ2 borehole volume strainmeter with high sample rate has good frequency response with the 100 Hz sample rate; and it has the ability to record a complete seismic wave; also there are basically the same frequency response range no matter how long the distance from the epicenter, and the frequency response changes are consistent. The high sample rate strain seismic wave and seismic wave can be highly consistent in time domain and frequency domain under some constraint conditions; however, the strainmeter with high sample had a weak response to the S seismic wave. -
. 2012, 32(1): 56-59.The mixed calibration of 8 LCR and 4 CG5 gravimeters carried out on the long baseline including 4 high precision absolute station of Wuhan, Zhengzhou, Beijing and Shenyang from May 5th to May 20th,2010 and from Jan 18th to Jan 26th，2010 is introduced. The results show that the quadratic terms exists in five gravimeters including all the 4 CG5 gravimeter, but the precision of them is relatively low. If we only calibrate the first order term, the precision of the first order term of the five gravimeters is better than the joint calibration and for the other gravimeters it is basicallly invariant.
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. 2012, 32(1): 60-63.The A10 absolute gravimeter is a high precision, high coherence, transportable and easy operating instrument in site to measure the vertical acceleration of gravity (g). Through a long time of field observations, we have recognized that the measurement number of sets, the number of drops and the measurement time of A10 absolute gravity gravimeter can be less than that of absolute gravimeter FG5 observations of the acquisition parameters set in the condition of meeting the accuracy demand. The results and accuracy can be affected by the observatory quality, weather and other external factors in different extent.
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. 2012, 32(1): 64-67.Through the variable substitution, linear regression models with two parameters are given in space of nonlinear functions. Based on the model establishment and significance test for simple linear regression, the comprehensive evaluation index is put forward for regression effect with different sample data. With measured data and Matlab program, the relation between cumulative deformation and monitoring date at each stage is analyzed. Then, the linear regression method is verified feasible for monitoring data analysis and realtime prediction.
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. 2012, 32(1): 68-71.The basic principle of nonuniform Bspline least squares fitting is discussed. Besides, the corresponding computation methods for irregular points and regular grid points are presented. Furthermore, an actual application in regional geomagnetic anomaly field are given. The results indicate that the accuracy and stability of this method can be ensured.
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. 2012, 32(1): 72-75.Coupling with the data processing of ThirdOrder GPS Geodetic Network, unified adjustment is done using loose resolution obtained by ThirdOrder GPS Geodetic Network data processing and station network data. The improvement in coincidence of results was discussed. Minimum curvature grid interpolation method were used to calculate horizontal velocity field, of which the results were better comparing with the method of average velocity in district.Highprecision velocity field can reduce error in epoch reduction process.
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. 2012, 32(1): 76-79.A spline interpolation can obtain higherlevel smoothness using lowerlevel polynomial. In GPS position calculation, if we use suitable method to supply boundary conditions, the spline interpolation function which has better convergence and stability can be proposed. The quintic spline interpolation algorithm is introduced and standardized satellite orbit based on GPS broadcast ephemeris is calculated. The experimental results show this method has higher accuracy of approximation and better smoothness, can avoid some shortcomings compared with other interpolation methods.
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. 2012, 32(1): 80-83.Gross errors make skewness influence on mathematical expectation of series, which will transfer to the residual sequence. The gross errors detection only with 3σ criterion may make a mistake of discarding the truth or accepting the wrong. The relationship between the poor of observations or error correction and gross errors was analyzed and the formulae to judge gross errors were deduced. The judgment condition matrix based on biopoor for detecting gross errors was constructed and the difference of small sample with large sample in detecting gross errors was compared.This method is verified effective through example analyses.
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. 2012, 32(1): 84-88.Affected by environmental and other factors, the navigation satellite atomic clocks must produce error and bias.
The research shows that clock errors and bias result from five type noise and there are several models with then the error and bias can be predicted. Each model has its disadvantages and advantages. In order to improve the reliability of the prediction of clock error and bias, it is useful to combine the forecasting result with each single model. This paper discusses the method for combining polynomial and grey model by use of the IGS precision clock series atomic clocks as an example.Finally, a useful idea from the result is adopted that the model combination is used to prediction the navigation satellite clock error and bias. -
. 2012, 32(1): 89-93.Aimed at the problems of outliers in multibeam bathymetric data affecting the survey results of seafloor terrain, a method of outliers detection and elimination based on trimmed least squares estimation is proposed. This method utilizes the high break point property of trimmed least squares estimation to fit a surface for a relatively accuracy seafloor trend surface, and identifies outliers by comparing the remnant of real depth values and the obtained trend surface with a certain threshold. By using the arrangement of bathymetric data points, a sliding window with variable size to detect and eliminate outliers in unit of survey line is designed. The results shows that this method can be used effectively to detect clusters and discrete outliers exist in seafloor terrain datasets.
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. 2012, 32(1): 94-96.On the basis of different characteristics of current ephemerides,two methods for satellite orbit prediction are introduced.Considering the request of realtime,the precision of orbit prediction is analyzed with different ephemerides.The results indicate that the precision of orbit prediction is the best with UltraRapid ephemeris and the precision is better than 20 m for seven days’ realtime orbit prediction.
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. 2012, 32(1): 97-100.The observations of repeated levelling network with both dynamic and static adjustment method were processed,and the two kinds of variation and velocity of each elevation point were obtained. The results
show that the dynamic method is more reasonable than static one for describing characteristics and course of crustal vertical motion because the former is independent of reference mark, and takes the time factor acquired data into account. The results from static adjustment, however, the variation, accuracy and velocity of unknown marks will vary with the location of reference mark, and a constraint numerical value will occur in results. This submerges or transfers the possible deformation information contained in raw data. It is suitable to make use of dynamic result for analyzing crustal vertical motion. -
. 2012, 32(1): 101-104.We present an analysis of two cycle slip detection methods: TurboEdit and TECR. The effects of cycle slip detection
with these two methods during ionospheric disturbance are studied. Cycle slip detection experiments were carried out by selecting observed data with different sampling intervals and different levels of ionospheric activity. The results show that, for the undifferenced GPS data, the TurboEdit combination cannot detect wide lane cycle slips within 6 cycles,while the TECR method can detect any combination of cycle slips, but the sampling interval must be less than or equal to 1 second. -
. 2012, 32(1): 105-109.Taking the disturbing gravity vectors calculated by the earth gravity field model of EGM2008 in 360 degrees as the “true value”, the computational results of Stokes integral model,the monolayer density model and the pointmass model are analyzed and compared. The results show that if taking account of the computational precision, the Stokes integral model is the best; if taking account of the computational velocity, the pointmass model is the best. In the specific computation, the proper model should be chosen according to the precision,velocity,parameters and the other requirements in the case.
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. 2012, 32(1): 110-113.When using 3D laser point clouds data to obtain DEM, there is need to mend the data, because the sampling blind exists and many nonground points were eliminated in the filtering process. The Kriging algorithm has been applied extensively in the data interpolation.In this paper,a new method to the parameter estimate of variogram theory model has been put forward.According to the principle of Kriging algorithm combining with surface fitting the defects of low efficiency is overcome. Finally, an example is investigated to verify the validity and practicability in the interpolation of point clouds data.
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. 2012, 32(1): 114-117.In deformation data processing,due to various approximations existing in the process of building model,it is inevitable that the model errors exist in the adjustment system.We discusses some theoretical problems affecting parameters estimation, proposes that model error can be solved with semiparametric penalized least squares and discusses the choice of regular matrix R and smoothing parameter α affecting the forecasted results.Finally,an adjustment problem in dam safety monitoring is used to test the method
and the semiparametric model, autoregressive model,grey model and grey wavelet analysis method are compared with each other.The results demostrate that the model errors can be compensated correctly by semiparemetric method. -
. 2012, 32(1): 118-122.For taking the problem in Compass two order ionospheric correction, the algorithm of wavelet package denoising is used to weaken the noises before ionospheric delay correction. Finally, the experiment is made by Compass emulational data and the results show that wavelet packet denoising method can decrease the observation errors and enhance the feasibility and validity of triplefrequency of two order correction greatly.
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. 2012, 32(1): 123-126.Under the premise of analysis of Kalman filtering with colored noise, aiming to the time series of GPS kinematic surveying, the time delay of the error sequence is analyzed and the GaussMarkov model is introduced to process it with colored measurement noise,
thus the time series without correlated noise was obtained. The time series of the residuals is divided into two sessions with each session period lasting for 5 minutes and then the spectrum analysis of the residual signal is made with FFT.Finally, the frequency spectrum of the error signal is obtained, and then the two frequency spectrum are compared with each other to obtain the natural frequency of the bridge, and the acceleration data is analyzed with FFT to gain the frequency spectrum to confirm the lowfrequency dynamic features extracted with GPS dynamic data. -
. 2012, 32(1): 127-131.Artificial neural networks (BP network, i.e. BackPropagation network) can be used to forecast the Length of Day (LOD) for its advantage of parallel disposal data and strong nonlinear mapping ability, but it can be easily affected by local minimum and resulting in slow convergence speed. Aiming at the shortage of the BP neural network, the wavelet basis function is used instead of the activation function of the BP neural network to improve its weight and threshold, then come into being optimized wavelet neural network which could effectually avoid local minimum and has swift convergence speed. As it is used to forecast LOD, good effects have been achieved.
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. 2012, 32(1): 132-135.In the GPS/DR integrated navigation, the signals of GPS are easy to be blocked by the ground objects, so the signal receiving to be interrupted and GPS positioning is suspended,DR system runs separately.In that case,the direction sensor errors of the DR system accumulate with time,which greatly affects the navigation accuracy.By making the map information be a constraint integrated into the navigation system algorithm,then it restricts the direction sensor errors of the DR system accumulate with time and effectively improve the positioning accuracy.
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. 2012, 32(1): 136-140.Genetic algorithm is used in searching integer ambiguity of GPS shortbaseline data. On the basis of realcoding and the properties that the sum of the chromosomes is invariant, and the biggest value of filial generation is the OR of parent, and the smallest is the AND of parent,an improved algorithm is proposed. The first filial generation is a random value between the biggest and the smallest values and the other is decided by properties that the sum of the two filial generations is invariant. The creation and variation of the initial population can also be achieved by random. Test results show that both the efficiency and reliability of this algorithm based on realcoded genetic algorithm are better than the algorithm based on binarycoding.
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. 2012, 32(1): 141-144.The atmospheric delay has limited the application of InSAR in the field of deformation monitoring and so on.
On the basis of relationship and difference of the spatial resolution of the GPS and InSAR atmospheric delay, optimizing LSSVM parameters by the PSO algorithm, and interpolating the GPS atmospheric delay, then correcting the InSAR atmospheric delay are carried out pixel by pixel. Through the experiment and analysis, the InSAR atmospheric delay could be corrected about 30 mm by GPS to improve the InSAR precision in the experiment region. -
. 2012, 32(1): 145-148.A new type of microtremor array is presented.Besides the advantages of traditional ones, it is improved by canceling the error item of 6th order Bessel function from space autocorrelation coefficient computed from the sitebetween distance of two groups and thus broadens usable frequency band and to some extents diminishes the influence from disturbance. The principle of design is introduced and effectiveness of the results is validated through simulation and field test.
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. 2012, 32(1): 149-151.The application of event timer (A032ET) in the absolute gravity instrument is introduced, and the event timer is compared with the time interval counter of FG5112 (SR620) in synchronized observation. The results show that the event timer is superior to the time interval counter in timing accuracy, data transport speed and storage depth.
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. 2012, 32(1): 152-155.An automatic deformation monitoring system——LandSlide Monitoring System (LSMS) using GEOCOM serialport functions for the secondary development of TCA2003 under the programming condition of VC++6.0 is developed. This system realizes following functions: automatic several observation sets measuring; automatic field data sheets generating; hydrograph plotting; deformation analyzing.
The developed system with simple operation and strong practicality has been successfully applied in the landslide deformation monitoring project on the left mountain body of Fuchunjiang power plant dam. -
. 2012, 32(1): 156-159.The development and application of extensometer have been for almost 40 years, it always focus on how to improve the precision but ignore its own characteristics. The SSY extensometer’s measuring sensitivity,resolution and transfer function are analyzed quantitative inputoutput test,reckon test of earth tide and stepinput response test.The results show the methods are feasible.
