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19 February 2013, Volume 32 Issue 6
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. 2012, 32(6): 1-7.This paper presents several applications of spherical dislocation theory to the 2011 TohokuOki earthquake. 1) We first calculate the coseismic horizontal displacements of the great earthquake using spherical dislocation theory. Our results show that as follows.a) The coseismic displacements are relatively bigger at areas perpendicular to the fault plane; b)most of the horizontal displacements point to the epicenter; c)as far as 5 000 kilometers from the epicenter the coseismic horizontal displacements reach up to 3 mm; d)in total, our theoretical predictions agree very well with the observations detected by GPS in far field. 2) Comparing with the theoretical displacements themselves, the discrepancies between two sets farfield displacements, which are deduced from two independent fault models, are about 1%-4% west to the epicenter but about 6%-15% east to the epicenter. The misfits near the epicenter are much bigger than those of farfield. Such discrepancies indicate the limited constraint capability of the dense GPS data on Japan Islands to the fault model of the 2011 TohokuOki earthquake, because of GPS stations’ ill distribution relative to the epicenter. 3)We constraint the total seismic moment of the 2011 TohokuOki earthquake within (3.24-4.96)×10 22 Nm using the farfield GPS data.The corresponding moment magnitude is about Mw8.97-9.10. 4) At last, the coseismic strains caused by the 2011 TohokuOki earthquake are roughly crosscurrent with the background of stress change fields at North China. As indicate that the crustal blocks at North China are relaxed as a whole due to the great earthquake.
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. 2012, 32(6): 8-12.Using InSAR technology and the ENVISAT ASAR data, this paper obtains the coseismic deformation fields of Yutian \%M\%w\{7.1\} earthquake happened on March 21, 2008.This paper inverts the coseismic slip distribution of Yutian earthquake with the Steepest Descent Method (SDM). The results are shown as follows.The inversion residual errors of the ascending and descending orbit surface deformation field are effectively controlled to small value; the major slip distribution is concentratedly located from 0 to 14 km depth along the fault plane; The largest slip value is about 5.47 m which is located in depth of 2.05 km along the fault plane of F2; the northern section of F1 is the obliqueslip rupture nearly equal to left lateral strikeslip and dipslip, while the middle section of F2 and southern section of F3N/F3S are basically the dipslip rupture with a little of left lateral strikeslip; The slip is mainly concentrated in the middle and southern section, and the slip of the northern section is small, the total seismic moment M0 from inversion is about 5.16×10 19 Nm, equivalent to moment magnitude Mw7.07.
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. 2012, 32(6): 13-16.There was a M7.3 earthquake at the boundary of Yutian County in Hotan Prefecture, Xinjiang, China, on March 21, 2008, which is considerably destructive. The derived deformation field is an effective way to retrieve the geophysical parameters and study the seismic mechanism. Taking the advantace of the wide swath and short revisit time, ScanSAR data were used for Yutian earthquake deformation field. First, the geolocation of Yutian areas was introduced. The process of ScanSAR interferometry was analyzed in detail. At last, the deformation field was derived with the extent of 400 km×400 km. At the same time, interferometry deformation filed of IM is derived with the extent of 100 km×100 km. With the application to ScanSAR interferometry in Yutian earthquake, it is significant for earth science research such as large earthquakes and crustal motion.
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. 2012, 32(6): 17-23.On the basis of velocity analysis of the 223 GPS regional sites in Xinjiang region during 2009 to 2011, the horizontal movement characteristics of the sites are obvious different from each other in the east to west and north to south partitioned by 85 °E and 43 °N .
The high surface expansion rates appear in two areas: Kashi region and YiningAksu region from the GPS observations where the earthquakes are prone to happening. Analysis of time series of the coordinate changes of 29 GPS stations during 2011.08 to 2012.25 shows that the variation of each station becomes larger after 2011.4 and after 2011.8, the value of the majority of observation stations appear in a process of smallincreasedecrease. The deformation results show there the energy accumulate obviously in the middle area of Tianshan mountain.The coordinate changes of the observation station XJKL located in the Junggar block and the stations in West Kunlun block show bigger fluctuation.The changes reflect that the crustal movement of the whole Xinjiang region becomes more active which is the background that earthquakes have happened frenquently in the period. To each station, the change is not obviously related relrted with earthquakes below \%M\%s6.0. -
. 2012, 32(6): 24-28.The presentday horizontal deformation and dynamic character derived from the latest GPS data of Xinjiang area in 1999-2007 and 2009-2011 is given.The results are as follows. The most of the regional characteristics of horizontal movement is complex and orderly, showing the feature of “the south big,the north small and the west big and the east small” in 1999-2007, which is inherited by that in 2009-2011, but the average value increases 1-2 mm/a, especially in the areas near Wenchuan and Yushu. The maximum value of surface shrinkage in 1999-2007 is about 60×10\+\{-9\}/a in the E and W direction, in alternating spatial distribution along KepingtaggQiulitaggXingdi fault zone located at the north edge of the Tarim block. The surface strain in 2009-2011 is still of shrinkage mainly, but the magnitude is bigger than the previous. The surface expansion size and spatial distribution range is larger and the maximum value is about 60×10 -9/a. The distribution of left and right revolving deformation in 1999-2007 are zonal in ENWS direction and is alternating in WNES direction respectively, but the order of revolving deformation in 2009-2011 is poor, the right revolving deformation value decreased from 20×10 -9 rad/a to 4×10 -9 rad/a in the joining zone of North and South Tianshan and in the Altyn Tagh fault the left revolving deformation value increased from 4×10 -9 rad/a to 25×10 -9 rad/a, Qilian fault’s revolving deformation is right from left and the maximum value is 40×10 -9 rad/a. These data show that there may be deformation adjustment in nearly two years.
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. 2012, 32(6): 29-32.Using campaign-mode GPS data of 6 periods from Crustal Movement Observation Network of China surveyed in 1999-2011 and data of 2 periods from Continental Tectonic Environment Monitoring Network of China surveyed in 2009-2011 we derive the movement rates of these stations. Both horizontal and vertical velocity fields in the Chinese mainland have been calculated with BERNESE GPS software. Preliminary results of the vertical velocity field demonstrate that the general trend of Tibetan Plateau is up with low rates.
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. 2012, 32(6): 33-36.Using kinematic analysis module TRACK of GAMIT/GLOBK to process 1 Hz GPS data of eight continuous stations around Japan by regarding the IGS site SHAO as a reference,we obtained and analyzed the kinematic deformation series which caused by the Mw9.0 Japan earthquake on March 11,2011. The result shows that most of the stations were moving towards southeast when the earthquake occurred.The maximum horizontal amplitude of MIZU and USUD , the two closest sites to the epicenter, are 3.11 m and 0.67 m ,respectively. To reduce systematic errors in the positioned result which are relevant to the surrounding environment of station, we filtered the kinematic deformation series of USUD in NS direction using modified sidereal filtering method. After applying modified sidereal filtering method,the root mean square error of kinematic deformation series of USUD in NS direction is decreased from 1.65 cm to 0.82 cm.
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. 2012, 32(6): 37-40.Dynamic evolution characteristics of the gravity field before Luhuo Ms5.3 on April 10，2011 and Qingchuan-Wenxian
Ms5.4 on November 1，2011 are studied. The result shows that the upspeed upspeed down variations of the gravity field emerged before those earthquakes.The variations of the gravity field formed dense，positive anomaly and closed contours in the place where it is the intersection of Xianshuihe，Longmensan and An’ninghe faults. -
. 2012, 32(6): 41-44.On the basis of the digital observation of crustal tilt and ground strain at Qianling seismostation, the digital records of the minutely coseismic observation curves since 2001 are studied and the physical characteristics of coseismic deformation responses
are studied.The results show that there are linear or proportional distribution relationship in a certain degree between the delay time of surface wave, the biggest shock, duration,and the magnitudes, the epicenter distances of all earthquakes.Besides,the coseismic attennation characteristics are related to some factors such as earthquake parameters, instrument performance, foundation structure. -
. 2012, 32(6): 45-49.On the basis of 5years rupture observational data of active faults of the Three Gorges reservior’s head area, and by use of gray statistics model, analyzed 8 fault and recognized 7 active fault according to 0.1 mm displacement criterion per year which is regarded as index for gray type.
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. 2012, 32(6): 50-53.On the basis of ETM+ image, ASTER GDEM data and its slope data, some different methods, such as image enhancing, analysis of shadow of mountain, analysis of the surface slope and threedimensional analysis, are efficient to highlight image features of faults. Thus the indicators for interpreting fault in Bortala Mongol Autonomous Prefecture were established. More than twenty main faults of NW, NWW, EW and NE trending surrounding the Bortala Prefecture were discovered. The interpreting results show a consistency with the local geology map.
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. 2012, 32(6): 54-58.A sorting work is carried out upon the repeated gravity data in the North China area from 1991,
and by using the sorting results, gravity variation before and after the 1998 Zhangbei 6.2 earthquake is analyzed. -
. 2012, 32(6): 59-64.The effects of reservoircanyon topography on the ground motion are analyzed with finite element method and following are obtained.1)The change of the height,the angle and the ratio of height to width of topographic features affect the peak ground acceleration and the spectrum of analytical model obviously. 2)The water level rising of water side will reduce the peak value of ground motion of the mountain part, and the high frequency components of input seismic waves will be inhibited more obviously. 3)The seismic response is sensitive to the frequency of input seismic waves.
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. 2012, 32(6): 65-70.A scenario earthquake method is proposed in order to evaluate the seismic risk in the region of the Three Gorges project under the condition that reservoir induced earthquake and tectonic earthquake exist simultaneously. The results show that
the scenario earthquake type affects all kinds of eigenvalue of the safety factor of landslide obviously and scenario earthquake location affects the stability evaluation. -
. 2012, 32(6): 71-75.This paper researches the correction method for the error of earth orientation parameters in AOD(Autonomous Orbit Determination) of navigation satellites. A correction formula of error of satellites’' coordinates which is resulted from error of earth orientation parameters is constructed, and two kinds of ground correction methods is put forward. The result of calculation indicates that the accuracy of correction method is high enough for meeting the requirement of broadcasting ephemeris.
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ON GPS FORECASTING EPHEMERIS AND CLOCK CORRECTION ACCURACY AND EFFECTS ON STANDARD POINT POSITIONING. 2012, 32(6): 76-80.Using IGS data and products the forecasted ephemeris accuracy and the forecasted clock correction accuracy as well as the standard single point positioning accuracy during 1995 to 2010 is analyzed. These analyses show that all the accuracy trend to increase gradually, such as the forecast ephemeris accuracy (SISRE) is below 2 m, and the predicted clock correction accuracy is (6-20)×10 -9 s, the standard positioning accuracy is 1.0-7.0 m in the horizontal and 2.5-27.0 m in the vertical.
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. 2012, 32(6): 81-85.The calculation adjustment formulas based on total least squares (TLS) is deduced. In total least squares adjustment(TLSA), the stochastic model is solved by matrix vector operator. Different from the published research, the observations and elements in coefficient matrix are heteroscedastic and correlated. In trilateration net, the known points are obtained from higher grade surveying and adjustment, so the coordinates of these known points have errors. Furthermore, the coefficient matrix of trilateration net’s error equation has errors and is correlated to the observations. Seeing that, the trilateration net total least squares coordinates adjustment is presented. At last, through an example, the method is discussed, and some conclusions are drawn.
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. 2012, 32(6): 86-89.The traditional method for space plane circle fitting includes two steps. The first step is to determine the space plane equation and transform the coordinate system into another coordinate system where z axis is perpendicular to the space plane. Secondly, the plane equation of a circle is fitted according to the x and y coordinates. Considering the space plane circle is essentially constructed by space plane and spherical plane which is intersected, an approach which takes a space plane equation and spherical equation as the constraint condition has been put forward, which includes directly calculating space plane circle observation equation and the corresponding calculation formula.
The measured data of a certain space circular object is taken as an example to verify practical application of the method. -
. 2012, 32(6): 90-93.The independent component regression is a method that combines the independent component analysis with regression analysis, that extracts mutually independent components from the arguments first, and then builds the regression model with the independent components.The simulation experiment shows that this method can not only solve the problem of relativity of the impact factors, but also give a better explanation about the dependent variable.
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. 2012, 32(6): 94-98.All types of nonconservative forces acting space missions are closely related with their configrations. Due to the impact of the selfshielding effect, surface area which is suffered from external forces may be smaller than the actual surface area.This paper puts forward a reliable and effective algorithm. This method models the complex spacecraft configurations as a combination of several basic geometric shapes which are then divided into several differential surface areas. Each element is checked individually by corresponding condition on
its shielding status, and the overall areas are determined by summing the exposed elements. It is indicated that the algorithm is effective in computation of the precise stress areas when Implemented in the calculation of solar radiation pressure force acting on GRACE mission, while traditional method manifests its limit in precision due to the neglect of selfshielding effect. -
. 2012, 32(6): 99-102.Aiming at the problem of the small samples whose distribution is unknown,a novel method using the grey envelope to detect the gross error in deformation monitoring data is proposed.Firstly, according to the uncertainty theory of grey system, the grey envelope for gross error detection is established,and then the principle and its steps for gross error detection are introduced.Using the method to detect the deformation in underground building of a hydropower station, we finally draw a conclusion that the proposed method is feasible and effective.
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. 2012, 32(6): 103-105.The combined model based on the quadratic surface model and BP neural network model is applied to the GPS height anomaly fitting, while the combination is determined from the variance reciprocal method and general regression neural network (GRNN). The GPS elevation data in a certain area is used, the results show that both the accuracy and reliability with the combined model are more superior to the single models, and the fitting accuracy with the combined model based on general regression neural network (GRNN) is better than that with the combined model based on the variance reciprocal method.
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. 2012, 32(6): 106-110.The weighted total least squares problem not only takes into account the errors of coefficient matrix but also consideres that the heteroscedasticity between the observable vector and the coefficient matrix.Seeing that the traditional iteration algorithm for solving the problem is too complicate,this paper considered the errors of observable vector as a function of the errors of coefficient matrix and the parametes.Through the linearization,it became adjustment of observation equations problems, hence the Lagrange multiplier method was used to carry out the iteration functions for this algorithm.And then,two numerical examples were given, and it was shown that the adjustment results with our approach is identify with Schaffrin & Wieser method.
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. 2012, 32(6): 111-113.Aiming at the situation that there is single gross error in the observation vector of the Errorsin variables(EIV) model, we propose the robust total leastsquares method. On the basis of the generalized maximum likelihood estimation, we use the observation vector residual function which grows more slowly instead of observation vector squared residuals items, and have deduced robust total leastsquares estimation calculation formula with the iteration method with variable weights. Finally, we apply the new method to the coordinate transformation parameters determination, and verify the feasibilities of the new method.
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. 2012, 32(6): 114-118.MODIS data is taken as the research object, which can provide a global continuous atmospheric vapor distribution. We introduced the principle of the vapor inversion from MODIS data, and also studied the theory and method to establish regional tropospheric zenith wet delay model. We obtained the regional tropospheric zenith wet delay model of the Fenwei basin. It is verified that the model can reflect the terrainrelated wet delay, which provided a reference for the establishment of the regional tropospheric wet delay model in other regions, or doing it from other data.
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. 2012, 32(6): 119-122.On the basis of a new model joining the IGRF model with the observation data of Chinese geomagnetic stations to build a magnetic field model throughout China is builtup,which simplified the calculation of the second order ionosphere effects.In this paper the results calculated by the new model is compared with the real data and it is given that the residual error is in 2.5 millimeter in the fixed number of year. The secondorder ionospheric correction for positioning calculated with the new model is basically the same as with the IGRF model. The model proposed in this paper can not only guarantee the accuracy,but also make the calculation of the secondorder ionospheric effects simplified and improve the computing speed.
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. 2012, 32(6): 123-128.The current development of IGSRTPP (International GNSS Service Realtime Pilot Project), its realtime products and data recovery are introduced. The realtime precise products from BKG (Bundesamt für Kartographie und Geodsie), ESA (European Space Agency), GFZ (Geo Forschungs Zentrum) and GMV(Guillermo Tobías González), which are IGS realtime analysis centers, are chosen and analyzed. Taking the IGS final products as a reference, the orbit can reach cmlevel accuracy while the clock offset subnanosecondlevel accuracy. The realtime orbit and clock products are taken as the input files of PANDA to do kinematic PPP(Precise Point Positioning) process at ALBH station with the results showing that the kinematic PPP process can achieve cmlevel accuracy in both horizontal and vertical direction.
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. 2012, 32(6): 129-134.This paper describes a simplified model of threedimensional datum transformation, which uses the direction cosines instead of rotation angles as parameters to be estimated. The Weighted Total Least Squares(WTLS) solution and Constrained Total Least Squares(TLS) solution are preferable to estimate the parameters when errors exist both in the observation vector and the coefficient matrix. Finally, the simulation and real experiments are investigated to verify that the coordinate transformation method described in this paper is effective. Compared with Least Squares solution, the result of Total Least Squares solution is more accurate.
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. 2012, 32(6): 135-138.A water surface height measurement method using reflected signal collected by a single geodeticquality receiver is developed. Signaltonoise ratio (SNR) is derived from the carrier tracking loop outputs and is the sum of the direct and reflected amplitude, as reflected amplitude is much smaller than the direct amplitude due to receiving antenna gain pattern effects and indirect signal attenuation upon reflection, then the reflected signal amplitude can be separated from the SNR data. Finally, a timevariying model which describes the functional relationship between the reflected signal amplitude and the height of reflector is derived, and LombScargle periodogram is used to solve the model. Two experiments have been conducted under different conditions. The sea surface height derived by GPS reflected signal show excellent agreement with tide gauge measurements.
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. 2012, 32(6): 139-143.This research focuses on the method and data processing of GPS singleepoch positioning technology for monitoring windinduced response of highrise building.Project monitoring results show that the quasi-static deformation measured by GPS during typhoon is consistent with wind loading information and three main modal parameters identified from the displacement information measured by GPS are fully consistent with the acceleration from accelerometers.
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. 2012, 32(6): 144-147.A novel face detection algorithm applied in 360 degree panoramic images with complex background and strong interference colors is proposed. Firstly, color space is transformed from RGB into YCbCr combined with hue information to obtain regions of skin. Secondly, morphological opening and closing operators can filter the noise effectively. Thirdly, the geometric features of human face are introduced to get rid of false skin regions. Finally, face recogniton is extracted with the average face model. Through all procedures above,the experiments show that the proposed algorithm with high efficiency and strong adaptability offers a suitable and robust solution to human face detection in 360 degree panoramic images.
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. 2012, 32(6): 148-151.How to determine sampling rate of highfrequency deformation instrument is studied. At first observation frequency range including passband and transition band should be determined based on the resolution of instrument dynamic range, and then sampling rate is determined according to the highest frequency and Nyquist’s Sampling Theorem. Finally the result is verified by simulation experiment.
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. 2012, 32(6): 152-155.A test of continuously observing strain changes in soil has been recording data for over three years in Wenan, Hebei province. A YRY4 type borehole strainmeter of high resolution is used for the horizontal strain observation. The selfchecking function of the YRY4 strainmeter which has four gages ensuring the reliability of the data. Relative insitu calibration is applied to evaluate the operation of the instrument, as well as correct the readings, which is very significant for precisely calculating the principal orientation of changes. Thus data credibility of four gages borehole strainmeter is defined here. A correction using the result of relative insitu calibration entails high data credibility of the YRY4 strainmeter at Wenan, indicates that it has been working well.
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. 2012, 32(6): 156-159.In order to make the installation, calibration, and maintenance of water level meter easy for earthquake monitoring staffs, we decided to upgrade the existing SWYⅠ water level meter to SWYⅡ water level meter, which not only retained the original good performance characteristics, but also absorbed the merits from other water level meters and the suggestions from the Fluid Research Group of China Earthquake Administration.At first, the development of the sensor by ourselves lays the foundation of selfmaintenance and followup upgrading. Second, the processes of selfexamination and examination ensure the high precision of the sensors and also guarantees the interchangeable features of them. Moreover, the display with network interface board uses 32 bit high speed ARM920T as the core processor, which has WINCE Operation System builtin. This design makes the low power consumption and the stable operation system possible. Besides, it is convenient for the insitu calibration and configuration with the new touchscreen on the instrument. Finally, the longdistance maintenance including remote software updating, queries of the work logs, power supply and signal can be achieved by the water level meters of new type.
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. 2012, 32(6): 160-163.This paper introduces a new laser detecting instrument for railway track flatness, it takes a silicon photocell as photoelectric receiver, and then the laser signal is converted into electric signal.In the instrument, the weak electrical signal is amplified by high power low noise amplifier, in which the variable magnification is controled by single chip microcomputer, thereby successfully solved the difficult problem that such as the different light source modulation signal amplitude, near and distant light signal strength caused by different signal magnitude varying considerably. Thus, the high accuracy detection has been achieved for different kinds of laser light source and light intensity changes in far and near distance. The adaptability and the detection performance of the receiver are ensured.
