Key Laboratory of Precise Engineering Surveying and Deformation Hazard Monitoring of Hunan Province

Changsha, China

Key Laboratory of Precise Engineering Surveying and Deformation Hazard Monitoring of Hunan Province

Changsha, China

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Lin M.,Central South University | Lin M.,Key Laboratory of Precise Engineering Surveying and Deformation Hazard Monitoring of Hunan Province | Zhu J.-J.,Central South University | Zhu J.-J.,Key Laboratory of Precise Engineering Surveying and Deformation Hazard Monitoring of Hunan Province | And 4 more authors.
Chinese Journal of Geophysics (Acta Geophysica Sinica) | Year: 2012

In this paper, we investigated the applications of geoid anomalies in geophysical interpretation. The ultra-high geopotential model E0M2008 is used to compute the gravimetric geoid, and the corresponding Bouguer and isostatic geoids are obtained from complete topographic and Airy-Heiskanen local isostatic corrections with a synthetic method combining the prism and tesseroid approaches. Then the geoids are divided into several residuals which represent anomalous features in different depths, by removing different wavelength components. Finally, a case study over the Hunan area based on these data sets and other geophysical data is presented. The results show that the residual gravimetric geoids can reveal some anomalous structures in deep earth effectively, such as the distributions of deep rifts, the locations of tectonic blocks and the lateral density distribution in the upper mantle etc. . However, the anomalous features in the crust are not evident in these residuals. The variation of density anomalies in the lithosphere is much smoother than that in the shallower depth, while the thickness of the lithosphere deepens from east to west. The Moho undulations, and the isostatic state of the research area which can be regarded as complementary information, are inferred roughly from the analysis of both the residual isostatic geoids and Airy local isostatic Moho depths. The results showed above give us a new way to overcome the absence and sparseness of gravity data in remote areas for geophysical interpretation.


Li S.-S.,Central South University | Li S.-S.,Key Laboratory of Precise Engineering Surveying and Deformation Hazard Monitoring of Hunan Province | Li Z.-W.,Central South University | Li Z.-W.,Key Laboratory of Precise Engineering Surveying and Deformation Hazard Monitoring of Hunan Province | And 5 more authors.
Chinese Journal of Geophysics (Acta Geophysica Sinica) | Year: 2013

The freezing-thawing processes of permafrost would destroy geological environment, and then result in rupture and collapses of buildings and roads, landslides, floods and the movement of glaciers, etc. Therefore, it is very important to monitor the ground deformation in the permafrost region for the stability and security of structures as well as development of economy. At present, there is no effective method for monitoring time deformation evolution of permafrost within large area. In this paper, we propose combination of small baseline subset (SBAS) technology for the measurements of deformation time series of permafrost. Considering that the deformation of permafrost is characterized by seasonal oscillation, a periodic model is introduced to replace the linear model in the conventional SBAS in order to better eliminate the effects of topographic residuals and atmospheric artifacts. 21 ASAR images acquired by the ENVISAT satellite are exploited by this method to monitor temporal evolutions of permafrost seasonal oscillation between 2007 and 2011 in the Qinghai-Tibet Plateau from Yangbajian to Damxung. By comparing with the field temperatures, it is found that the retrieved deformation sequences conform to physical characteristics of permafrost very well. The results demonstrate that SBAS-InSAR algorithm has good prospect in deformation monitoring over permafrost regions.


Yi H.,Central South University | Yi H.,Key Laboratory of Precise Engineering Surveying and Deformation Hazard Monitoring of Hunan Province | Zhu J.,Central South University | Zhu J.,Key Laboratory of Precise Engineering Surveying and Deformation Hazard Monitoring of Hunan Province | And 6 more authors.
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2014

The kernel pixel's iteration formula was weighted by coherence and anisotropic gradients between surrounding pixels of the window and the kernel pixel. By this means a new filter for interferogram was presented, which could keep the fringe detail as well. Taking the simulated data and actual interferograms of Etna volcano in Italy and earthquake in Turkey for example, this new algorithm was compared with complex space domain adaptive filter, Lee filter and optimal integration-based adaptive direction filter. The results show that this new method performs well not only in noise reduction but also in preservation of the sharp sawtooth profile of fringe. The residual points reductions in simulate and actual interferograms are 99.3%, 90.3% and 87.9% respectively, in favor of following phase unwrapping.


Yang Y.,Central South University | Yang Y.,Key Laboratory of Precise Engineering Surveying and Deformation Hazard Monitoring of Hunan Province | Zhu J.,Central South University | Zhu J.,Key Laboratory of Precise Engineering Surveying and Deformation Hazard Monitoring of Hunan Province | And 2 more authors.
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2013

To obtain 1:50000 topographic map of the western mountain area, the method based on R/D model and similar transformation model to acquire SAR planimetric position was put forward. The results show that this method improved the accuracy of geo-location by accommodating topographic effects and orbit error. The accuracy of R/D model geo-location is 8.9148 m and 2.2365 m in the east and north, respectively. The accuracy of the improved method geo-location is 0.6648 m and 0.2533 m in the east and north, respectively, and overall planimetric accuracy is within 1.0 m. The improved method can satisfy the requirement for 1:50000 topographic map generation, which confirms the new method is very effective.


Yi H.,Central South University | Yi H.,Key Laboratory of Precise Engineering Surveying and Deformation Hazard Monitoring of Hunan Province | Zhu J.,Central South University | Zhu J.,Key Laboratory of Precise Engineering Surveying and Deformation Hazard Monitoring of Hunan Province | And 5 more authors.
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2013

Algorithms and their advantages and disadvantages of filters for InSAR fringe images in frequence and space domains were described. The algorithm theory of the complex space domain adaptive filter was discussed. An improvement was made in two points, one was adding the gradient computation in 45° and 135° directions, and the other was the determination of scaling function for fringe edge based on interferogram coherence coefficient, thus modifying weight coefficients. According to the simulation data and actual interferograms of Hongkong and Etna volcano in Italy, the proposed method was compared with the complex space domain adaptive filter, Lee filter, Goldstein based on SNR (signal-noise-ratio), and adaptive direction-dependent based on optimal integration. The experiment results demonstrate that this improved method has capability of tuning the filtering according to noise intensity. It performs well not only in noise reduction but also in preservation of the sharp sawtooth profile of fringe, with an improvement of 18.9% and 17.2% of residual points reduction in simulate and actual experiment respectively, showing stronger local adaptability.


Yi H.-W.,Central South University | Yi H.-W.,Key Laboratory of Precise Engineering Surveying and Deformation Hazard Monitoring of Hunan Province | Zhu J.-J.,Central South University | Zhu J.-J.,Key Laboratory of Precise Engineering Surveying and Deformation Hazard Monitoring of Hunan Province | And 4 more authors.
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2012

The filters for InSAR interferograms used in monitoring mining area deformation were introduced. The edge-preserved Goldstein filter was presented in order to avoid the loss of fringe detail of InSAR interferograms with strong noise and dense fringes caused by over filtering when processed repeatedly by traditional methods such as Goldstein filter. The interferogram was filtered by edge-preservation filter with strong edge-preserving performance. The result was further smoothed by the improved Goldstein filer, whose filtering parameter was determined by pseudo-coherence and phase standard deviation derived from the result. The experiment results demonstrate that the new filter is 23.7% higher than that of once Goldstein filter in noise reduction while its edge preservation is 0.74, superior to twice Goldstein filter. This method performs well not only in noise reduction but also in detail preservation when applied to InSAR interferogram with strong noise and dense fringes.

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