Based on the horizontal movement field and continuous principal strain field calculated from the GPS data of 2011 and 2013 in Northeast China, the crustal movement and strain\|stress state in Northeast China are researched. The offset rates of major fault zones in Northeast China and fault strain\|stress state are calculated by computation of the block motion parameters, and then the fault zone activities are researched. The results suggest that during the period of 2011-2013, the regularity of the East movement field of Northeast China is relatively good, and the East movement field converges along Hunchun\|Longjing zone with Eastward displacements. The consistency of the central and West movement field of Northeast China is relatively weak, and the displacement directions are relatively scattered. The main strain results reflect that the direction of the principal compressive strain axis of Northeast China during 2011-2013 is NE55°. The distribution area of the compressive region with both horizontal principal strain axes shortened is smallest, and the extension region with both principal strain axes stretched is the second smallest, and the region with the minimum principal strain axis shortened and the maximum principal strain axis stretched (shear activity area) is the largest proportion. Ms≥5.0 earthquakes during this period are concentrated in 2013, and most of the earthquakes occurred on the surrounding zone of movement direction transition and compressive\|shear area, and the biggest Ms 5.8 earthquake occurred on the transitional zone of different movement fields and tectonic belt with relatively strong compression action.
Based on Gaussian distance weighting theory, the paper developed a MATLAB program to compute variables as strain rate in the average distributed grid points in the North China district by using the GPS horizontal velocity derived from GPS observation data from 1997 to 2009. The computing results proved that it is reasonable to choose 150 km as the Gaussian smooth radius. The capital area displayed left\|lateral shear along the Zhang\|Bo fault zone, while the Tangshan-Qinhuangdao district had extensional performance in the north-south direction. The Shanxi belt presented right-lateral shear deformation overall, with tension deformation in the north part and extrusion movement in the south part. The deformation along the Tan-Lu fault zone was insignificant but with small shear movement in part of its north and south districts. The Ordos block was stable in the interior, but displayed left\|lateral shear accompanied by extension in the north rim and extrusion in the west rim. The Qinling block that is in the south rim of Ordos block displayed left\|lateral shear and right-lateral shear at its north and south sides respectively, along with extrusion and extension at its west and east sides.
Through Zhangjiakou to Zhangbei precise leveling data processing. This article analyzes a spatial evolution image of the regional vertical deformation rate. It advances suggestions on the earthquake situation trend.
High precision GPS horizontal velocities of GPS seismic monitoring network and gravity data were used to estimate the block motion and major fault slip rate in Fujian Area.The results are as follows: Due to the influence of collision of the Eurasian, Philippine Sea and Pacific plates, crustal deformation of blocks in Fujian area are prominently in a clockwise rotation.Further, this leads to left-slip motion along the NE-striking faults and right-slip motion along the NW-striking faults. The Changle-Zhaoan, Shaowu-Heyuan and Yongan-Jinjiang faults are the most active left-lateral faults in the region, with a rate of 0.7±1.3mm/a, 0.7±1.7mm/a and 0.6±1.8 mm/a respectively, and the Jiulong river downstream area has a right-lateral slip rate of 0.5±1.7mm/a.
According to data obtained from several main technical methods and the vertical motion model used in regional crustal vertical movement research, incompatibility（model error）and its impact on results are discussed in this paper. The basis of judging model error size and principal, methods about data selection are pointed out. Further, some problems that need to be addressed when researching the evolutionary process of vertical crust movement and discriminating the regional seismic hazard are discussed.
A method of kinematic deformation surveying by single epoch is described here to obtain the large deformation.At first, we use the wide-lane measurements and the approximate coordinates of monitor sites to resolve the initial wide-lane ambiguities.Based on the correlations between the ambiguities, the ARCE method is used to search the correct wide-lane ambiguities.A rough deformation is obtained.Then, we use the L1 measurement and the method of without cycle slip detection and ambiguity resolution to obtain the residual deformation.The tolerance of position error for a priori coordinates is increased to 70 cm,which is suitable for kinematic deformation surveying.
The particle swarm algorithm is a newly developed optimization. Application of the particle swarm algorithm in geodetic inversion problems is rarely reported in China. In this study, by using the particle swarm optimization algorithm combined with the dislocation model，the three dimension slip velocity of the Qilianshan mountain fault is inversed by using leveling data observed in Hexi region during 2001-2004.The results show that the particle swarm optimization algorithm can compute three dimension slip velocity of the fault effectively. The results of the numerical inversion are consistent with those obtained by geological methods.
Using six global ocean tide models and China’s regional tidal data, tilt ocean tidal loading is calculated by using the integral Green’s function. Comprehensive analysis of the standard deviation, root mean square(RMS),and root sum square(RSS) show that the tilt ocean tidal loading is generally 10-8rad,with a maximum up to 10-7rad, in coastal areas of China. There is great difference among models. We need to exercise judgment to adopt one that is most suited for the specific area.
Multi-satellite altimeter data were used to study and the method of combined crossover adjustment was completed.Systematic bias might be reduced with the method.The meridional component and prime vertical component of the residual vertical deflections of Zhejiang offshore were determined using the weighted method of alongtrack least squares with an appropriate search radius.On the basis of removerestore method and FFT technology，the gravity anomaly model and geoid model gridded with a spatial resolution of 2.5′ of Zhejiang offshore were determined using the residual vertical deflections with an appropriate integration radius，under the consideration of effects of innermost zone.The gravity anomaly computed by the method was compared with the shipborne gravity，the RMS of the difference is ±5.231 58 mGal.The marine geoid was compared with the results calculated with EGM96 and EGM2008，the RMS of the difference is ±0.694 57 m and ±0.029 51 m.
In this paper we examine the problems in the density inversion from satellite gravity gradient data which including plan model error, the regulation of ill-conditional matrix, the inversion of big matrix, the combination of nonlinear prior data, etc. Using the Tesseroid model we complete the simulation model inversion adding the white Gauss noise based on methods which include general ridge estimation, ART (algebra reconstruction technique) and genetic algorithm. Finally, all the results are compared and analyzed with the prior model..
The observations of Tengchong continuous gravimeter of CMONOC from July 1, 2012 to June 30, 2013 are analyzed. In addition, its precision and noise levels are obtained. The results show that the noise level of Tengchong station from 1s to 100 s is about 9×10-8ms-2, and from 100 s to 100 m in is about 0.3×10-8ms-2, while the white noise level is 0.509×10-8ms-2. The precision of main tidal factors (such as O1 and M2) extends to the superconducting gravimeter SG-052 used at observing stations of the Gravity Network Center of China. M2 has the highest precision reaching 0.00 018. Tengchong continuous gravity observation can provide high precision and reliable continuous gravity data for studies about strong earthquake monitor, volcano movement monitor and gravity change before earthquakes in the Sichuan-Yunnan region.
We analyze the mass change of the Antarctic in three different GIA models: the new gravity time variable Tongji-GRACE01 model, and the two steps filtering methods (Gaussian filtering and de-correlation filtering). The RMS of the mass change time series are compared. From Jan. 2003 to Aug. 2011, the trends of mass changes are -128.2±34.6 Gt/a (Pau-5-AUT corrected), -177.9±40.2 Gt/a (W&W-4-AUT corrected) and -92.8±31.2 Gt/a (W12a corrected) respectively.
Assuming the geoid as spherical approximation，the topography correction was calculated by dividing the actual topography into the Bouguer shell and the rough terrain based on the radius of the calculated point.The comparison of the local terrain correction with the Bouguer planar shows that there is difference between the rough terrain correction and the local terrain correction；the difference is small in the even area.It is more than 0.5 mGal in the areas where the elevation is higher than 1 000 m.The integral range of the spherical rough terrain correction is easy to extend，so it can present the more signals than the local terrain correction，and it is more consistant with the actual earth shape.The regular topography correction calculated with the Bouguer shell and the Bouguer planar is the same in shape，but the difference of range is very large.
In this paper, we use ionospheric TEC data provided by International GPS Service (IGS) tracking stations to examine the ionospheric variations during the Ms8.0 Wenchuan earthquake that occurred on May 12, 2008, in China. In data processing, the ARMA model based on the theory of time series is adopted, and the predicted TEC of ARMA model is regard as the background reference value of TEC in the ionosphere. Comparing the results with the previous conclusion, we also found the anomalous ionospheric disturbances 13 d,12 d,10 d and 7 d before the earthquake. The results indicate that the establishment of the ARMA model is reasonable and reliable, and it also can achieve high accuracy in the detection of the ionospheric TEC anomalies prior to earthquake effectively, based on the data derived from IGS.
In order to compare the zenith tropospheric delay (ZTD) estimated by precise point positioning (PPP) using BDS and GPS data respectively under the conditions of the existing constellation, the solutions by BDS only, GPS only and combined BDS/GPS are presented and analyzed. We use real tracking data of a single day from IGS and MGEX stations with precise orbit and precise satellite clocks obtained from CODE and WHIGG. The experimental results show that an accuracy of X mm level can be achieved by GPS, while less than 2cm can be achieved by BDS compare to IGS ZTD products. This suggests that a more accurate result is obtained by GPS than BDS. In addition, a similar result is achieved by combined GPS/BDS as compared to that of GPS only.
A combined GPS/GLONASS precise point positioning (PPP) approach is used to obtain the three-dimensional distribution of atmospheric water vapor. To verify the effectiveness of the combined GPS/GLONASS PPP, and GPS, datasets at 12 stations on 6 d were collected at the time when COSMIC RO events occurred in or around Hong Kong. The test results indicate that the number of the voxels from GPS/GLONASS PPP that are passed by the satellite rays increased by 18%, and the water vapor accuracy from GPS/GLONASS PPP is 10% higher than with the GPS PPP method.
The high temporal transient changes of water vapor content can be reflected by high frequency zenith tropospheric delay(ZTD)which is important for rainstorm shortterm precasting.Based on the precise point positioning(PPP)technology，the PPP-ZTD precision with the different sampling interval satellite clock biases(SCB)was analyzed.The result indicates that the precisions of PPP-ZTD(RMS <4 mm)with 5 s and 30 s sampling interval SCBs were better than the precisions of PPP-ZTD(RMS<6 mm)with 5 min sampling interval SCB.Both the obtained PPP-ZTD precision with the sampling interval of 5 s and 30 s SCBs are considerable.
Ionospheric 2nd-order and 3rd-order items of GPS observation are calculated by RINEX HO software. On this basis, higher-order ionospheric delay (ΔIH)p,qi,g of the GPS double difference observation is determined. The relationship between (ΔIH)p,qi,g and geomagnetic latitude, baseline length, baseline direction and the sun's activity level are studied. Then, under the assumption that other conditions are the same, the Bernese 5.0 software are applied to the baseline solution for the observed values, both under and not under the higher-order ionospheric delay correction. Higher-order ionospheric effects on baseline vectors ΔbH are calculated. The results show that the value of ΔbH is very small and can be ignored in the general case. ΔbH has no exact relationship with the factors such as baseline length, solar activity level and so on, but with the decrease of the time, ΔbH will increase.
The model of ionospheric delay correction is established by fusing BDS, GPS and GLONASS with observations of pseudo distance smoothed by carrier phase and spherical harmonics. Some experiments of inversion of the global ionosphere have been done. The fusion of the three systems not only increases the number of satellites in observation, but also improves the geometric distribution of the puncture point. We fused the variation process of ionospheric daily in October, 2013 to obtain the monthly comprehensive differential code bias product and analyzed the accuracy of the products. The analysis result shows that: the ionospheric grid differs from product of IAACs within 4 TECu, mean 0.675 TECu. Furthermore, compared with the measured TEC by GNSS from reference station, the mean of the difference is less than 5 TECu. In addition, the outside precision and stability analysis of the monthly comprehensive differential code bias product indicates that the precision of GPS is better than GLONASS, while the stability of BDS is poor.
Atmospheric delay phase is one of the main factors affecting the measurement accuracy of InSAR technology limiting its application in high-precision deformation monitoring. When there are more SAR images, InSAR time series analysis techniques can abstract the the atmospheric phase from numbers of interferograms according to the spatial and temporal phase characteristics. This can be used to correct the atmospheric delay phase in the interferograms.However, there is little research on the reliability of the separated atmospheric delay phase. In this paper, we do a test to separate the the atmospheric delay phase with 40 Envisat ASAR images covering the Datong area. The reliability of the separated atmospheric delay phase is analyzed with the terrain and MODIS data.
GNSS precise point positioning software PANDA was used to process GNSS data of Hainan GNSS regional network in 2009，2011 and 2013，and calculate coordinates and velocity of various points in ITRF2008.The average velocity of Hainan regional network is 32.16 mm/a in east direction and -10.08 mm/a in north direction.The results are basically consistent with that of GAMIT/GLOBK solution.
Probability histograms of three quadruple difference series are extracted from 24hours GPS observations of two IGS stations with 5Hz sampling rate based on this, it is pointed out that quadruple difference series are not nearly applicable for stochastic modeling due to requirements of high sampling rate, baseline length and probability distribution assumptions on different stations and satellites. Undifferenced combination observation using both geometry-free and ionospheric-free criteria (short for UGIF) is derived from dual-frequency observations, and then a stochastic modeling method for GNSS undifferenced pseudo-range observations is presented based on UGIF. The proposed method can estimate the stochastic model of a single station and satellite pseudo-range observations with high or low sampling rate in real-time or post-processing modes. Finally a case is implemented to test the validity and rationality of the UGIF method using dual-frequency GPS and GLONASS observations collected at CUMT’s single reference station.
Multipath effect is one of the main errors that affect the positioning accuracy of satellite navigation receiver. Aiming at multipath modeling, firstly, property of static multipath is analyzed, parameters that influence multipath are extracted, and correlation relationship between them is established. Then, segmented spherical harmonic and segmented trigonometric series function model of multipath are constructed, and the precision and complexity of these two models are compared. The result shows that segmented constructing multipath model using trigonometric series model and spherical harmonic function model is feasible and the former is better than the latter.
The resolution of ambiguity for long range reference stations at single epoch and the method of getting undifference regional error correction and an algorithm of dynamic ambiguity resolution on rover at single epoch were introduced in the paper.The test results using actual measurement data indicate that the rover position at centimeter level can be got by use of the algorithm at single epoch for long range network RTK.
In penalized least squares estimation with the semiparametric model，the key is how to calculate regularization parameter effectively.An optimization method with a new model of the penalized least squares,was proposed for calculating the regularization parameter based on criteria of the generalized cross validation and L curve.The results of simulation calculation show that themethod is more effective for calculating regularization parameter.
Neither least-squares nor total least-squares can be applied to the condition that a coefficient matrix has bounded errors very well. In addition, the adjustment of bounded uncertain data cannot be directly applied in this condition. Therefore, the part bounded problem is analyzed in this paper. An iterative algorithm to solve this issue is proposed based on the adjustment of bounded uncertain data. The validity of this method is proved through an example.
In the geodesy，many models are nonlinear.The classical methods dealing with nonlinear models are either linear approximations using the approximation value of parameters or iterations.Some nonlinear models can not be linearized and are very difficult to evaluate precision of estimators by the methods.To solve the problems，the penalized least square estimator for nonlinear models were presented and related estimation formulas supported.That is the key lying in that substituting the nonparameters of semiparametric models for the Taylor expansion reminders.The results calculated with the method show that the method is effective for the nonlinear models.
Aiming at the adjustment problem that there is a constant vector in the coefficient matrix of the linear regression model, we propose the total least squares adjustment model of linear regression. On the basis of the model, we deduce a computational formula of total least squares estimation. Finally, we apply the method to an example, and verify the feasibility of the method．
In this paper, the estimator is based on a linear transformation of the LS estimation.It provides an optimal solution to the true and a constrained covariance matrix. The regularization techniques are unified with the respect to filtering factors. Filtering factors and corresponding eigenvalue of error covariance matrix of some known regularization estimators as Tikhonov-Philips regularization, truncated singular value decomposition, generalized ridge regression and others are provided.
This article employs the method of applied numerical analysis theory to discuss the square matrix singularity discriminant. Focusing on the problem of ill-conditioned transformation model for planar four parameters normal equation coefficient matrix, the author puts forward the approach of coordinating the centralized coordinates with reducing the error equation coefficient. This approach effectively improves the structure of normal equation coefficient matrix and the ill-conditioned transformation model, and gains stable and reliable transformation parameters. Also, the article verifies that this method is simple and feasible through theory and case analysis, providing reference for the planar four parameters transformation in regional engineering surveying.
The reason of ITRF computation inconsistency at normal equation level and the advantage of combination computation at observation level are analyzed. After summarizing the research status of combination computation at observation level, the solution procedure and key issues of combination computation at observation level are analyzed. In order to overcome the computing difficulty of combination computation at observation level, the combination computation strategy based on distributed process is advanced. And then the parallel computing flow and method of the ITRF solution are designed. The study results show that the ITRF solution strategy at observation level can improve the product consistency and the distributed process technique can improve the efficiency of ITRF solution.
First of all, the framework of sediment classification system based on echo intensity is introduced, The paper then analyzes storage structure and content of ALL format multibeam sonic data with multibeam sonar principles. It can decode ALL format data,and extract all kinds of data packets from ALL raw file by means of software developing.By means of a series of data preprocessing, it can create high-resolution sonic images based on a footprint envelope grid from these sonic data. In the end,the sediment classification is implemented with improved BP neural network in the sonic image.The experiment proves that it can obtain good effects for sediment classification with sonic image, and provide an accurate and reliable basis for submarine microgeomorphology recognition.
As a consequence of variability in water vapor content in the atmosphere, phase artifacts in interferometric synthetic aperture radar (InSAR) images (which are caused by path delays as the radar signal propagates through the stratified and turbulent atmosphere and ionosphere), frequently degrade the interpretability of the phase and correlation signatures of terrain. The effect of atmospheric delay consists of three parts. In this paper, the three phase delays are calculated using network methodology respectively. It is applied to 20 scenes of ENVISAT (ASAR) images from 2007 to 2010 over the Bengco zone of Tibet. The 1-D covariance function is used to estimate atmosphere artifacts. The experimental results suggest that after atmospheric effects are mitigated, the mean variance of the exponential function of the interferograms is reduced from 3.1mm2 to 0.6mm2, and the average e-folding wavelength is reduced from 1.5 km to 0.21 km, which means the APS correction has reduced the mean amplitude and wavelength of the covariance by about 80% and 86%, respectively.
The contact algorithm was applied to construct a 2-dimension FEM simulation model which indudes the active faults.We explore a proper scenario earthquake parameter setting for the NGA model in oder to supply the input time history.We find that the horizontal bedrock ground PGA at the Three Gorges Dam project is about 175 Gal when the M5.5 reservoir induced earthquake occourred on Jiuwanxi fault. A M5.5 earthquake caused by Gaoqiao fault will make the horizontal bedrock ground PGA at the Badong rise to 303 Gal.We also find that the bedrock ground motion PGA on both sides of faults distributes discontinuously. This phenomenon indicates that it is necessary to consider the fault when we calculate the bedrock ground motion parameters.
Approximate entropy is a quantitative description of the nonlinear dynamics of the complexity of the system changes. In this paper,The geomagnetic Z-component approximate entropy is estimated on four stations(CDP,COQ,XIC and HZH) from July 2007 to June 2012, respectively. The results show that the entropy changes dramatically before the Wenchuan earthquake on four stations,but the biggest change is in CDP(Chengdu station). The preliminary view is that this process is associated with the Wenchuan earthquake gestation process, and the change amplitude may be related to the epicentral distance. This result is beneficial to exploration of the seismogenic mechanism and large earthquake prediction.
For several days just before the M7.0 Lushan earthquake, the YRY-4 four-gauge borehole strainmeter at Guzan, Sichuan, recorded prominent abnormal changes. The strain anomalies are striking on the smooth background of several years recording after Wenchuan earthquake. However, as the small town of Guzan is in rapid development presently, constructions of various kinds significantly affect the observation. Whether or not the observed anomalies before the Lushan earthquake were caused by any of the constructions is a question that must be answered. Among all the interferences, apartment building, sports ground reconstruction and tunnel cutting can be first excluded by an analysis of the typical figure of the anomalies. Two other possible interferences are: the road construction in front of the station, and the flow variation of the nearby Daduhe river due to the building of an upstream reservoir. Local investigation, comparison of strain and seismographic recordings, comparison of strain and Daduhe river flow recordings, and analysis of the sense of the strain anomalies have been carried out. It is concluded that the abnormal variations cannot be attributed to any interferences, but should be related to Lushan earthquake.
This paper takes extensometer and horizontal pendulum data in Yushugou as dependent variables and meteorological factors as independent variables to do correlation and regression analysis. The best regression equation is confirmed according to regression testing and comparing the various factors. Through the analysis of the regression residuals, the paper summarizes typical earthquake examples. Our research supports the following results: 1) Earth temperature is the main impact factor in the annual change of Yushugou fixed deformation (except pipe tilt meter NS) showing a quasi-linear relationship; 2) The air temperature is the main impact factor in the annual change of Yushugou pipe tilt meter NS, showing a quasi-linear relationship; 3) Two components of horizontal pendulum to observation data associated with geothermal show a highly negative linear relationship; 4) NE, EW of pipe tilt meter and three components of extensimeter show a highly positive correlation with the earth temperature; 5) NS of pipe tilt meter has a high positive correlation with air temperature and a negative correlationwith air pressure; 6) NE of extensimeter has positive correlation with earth temperature and air temperature; 7) Regression analysis can eliminate some influence of meteorological factors, helps us to recognize the seismic anomalies
We have completed some application experiments by the MSM on Jianghan Plain and the Yangtze levee. The results show that the dispersion curve is more stable from the SPAC than the F-K method. We can get the 1-D underground structure information from several meters to hundreds of meters by transferring the size and geometry of the recording array. The 2-D and 3-D structures of the earth can be obtained by translating these results. Due to its merits of passivity, non-invasiveness and strong adaptability to the environment, the MSM has important application values in the field of earthquake engineering and engineering geophysical exploration in urban areas.
This paper proposes a method of modeling the rotation trajectory of satellite tracking theodolite and puts forward an algorithm which can make automated planning about the rotation trajectory of the theodolite on the basis of the satellite’s trajectory and the theodolite’s historical trajectory. This algorithm plans the rotation trajectory in advance which can keep the hardware safe and at the same time avoid the lost of observation arcs owing to the situations when the rotation is limited and the theodolite has to reverse or motor’s power was shut down and the theodolite has to be pushed back. This algorithm can be applied to the SLR theodolite and others tracking the satellite.
This paper takes T3 laser tracker of API as an example to analyze measurement accuracy of laser tracker by experiments including contrast measurement before and after instrument calibration, repeated measurement of fixed point, contrast measurement with interferometer, mean square error of a point, and contrasts laser tracker measurement with the conventional measurement method. The results indicates: for laser tracker short range measurements, distance measuring error plays a leading role in measurement accuracy and gets worse as distance increases, but angular accuracy is stable. The measurement accuracy of laser tracker is higher than the conventional measurement method.
