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Wang Q.-J.,Central South University | Li Z.-W.,Central South University | Du Y.-N.,Central South University | Xie R.-A.,Geology Surveying and Mapping Institute of Guangdong Province | And 3 more authors.
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2014

Empirical functional models for the maximum and minimum detectable deformation gradient of PALSAR interferometry were established based on coherence and discrete look numbers. Then, a least square regression method was used to fit the model coefficients and thus obtain the generalized functional models for both coherence and look numbers. The experimental results with ALOS PALSAR data of Wenchuan earthquake of China show that the new model works well for judging whether the deformation gradient can be detected by the D-InSAR technology or not. The results can help researchers to choose PALSAR data and to configure processing parameters, and also benefit the interpretation of the measured surface deformation. © 2014 The Nonferrous Metals Society of China.

Wang Q.-J.,Central South University | Wang C.-C.,Central South University | Xie R.-A.,Geology Surveying and Mapping Institute of Guangdong Province | Zhang X.-Q.,Geology Surveying and Mapping Institute of Guangdong Province | Zhu J.-J.,Central South University
Geosciences Journal | Year: 2014

Considering the deformation of discrete monitoring points within the same deformable body usually have similar physical properties and tend to undergoing identical dynamic process, joint modelling of the deformation processes of these points in time domain are expected to generate better results. Yin et al. (1997) first extended the multi-variable grey model-system cloud grey model SCGM(1,m), with obviously superior modelling mechanism than single-variable grey model, to multi-point deformation modelling. However, this model is still not widely recognized and its applications remain very limited in the field of deformation analysis. The objective of this study is to demonstrate the capability of the SCGM(1,m) model, to present two revisions to further improve the performance of the model and to draw more attention to the community of deformation analysis. We first introduce the principles of the SCGM(1,m) model in the analysis and prediction of deformation surveys. Two practical techniques, namely residuals re-modelling and linear regression adjustment, are then presented to improve the SCGM(1,m) model. Combined with slope monitoring data, the modelling with the original and the improved SCGM(1,m) models by residuals re-modelling and linear regression adjustment are illustrated. The mean relative prediction errors decrease from 5.89% to 3.54% and 2.69%, when the two refining techniques are applied, respectively, indicating relative improvements of 39.9% and 54.3%. © 2014, The Association of Korean Geoscience Societies and Springer-Verlag Berlin Heidelberg.

Hu J.,Central South University | Wang Q.J.,Central South University | Li Z.W.,Central South University | Xie R.A.,Geology Surveying and Mapping Institute of Guangdong Province | And 2 more authors.
Natural Hazards | Year: 2014

In this paper, synthetic aperture radar (SAR) data from ENVISAT ASAR ascending, descending and ALOS PALSAR ascending orbits are collected to investigate the coseismic displacements of the Mw 6.4 earthquake occurred in Gaize, Tibet on January 9, 2008 and the Mw 5.9 aftershock on January 16, 2008. Two interferometric phase analysis techniques, i.e., D-InSAR and multi-aperture InSAR, are employed to process the SAR data, with which the displacement measurements along three different line-of-sight (LOS) and three different azimuth directions are retrieved, respectively. Complete three-dimensional (3-D) coseismic displacement fields caused by the earthquake are then resolved by integrating the obtained LOS and azimuth displacement measurements with a weighted least squares adjustment, whose distributions are conformed to the two north-northeast trending northwest-dipping normal faults detected in previous studies. Ground subsidence and uplift are observed in the hanging wall and footwall of the main fault, respectively, and the subsidence reaches its maximum in the hanging wall of the second fault as a superimposed result of the Gaize earthquake and its aftershock. Anti-symmetric horizontal movements are also detected during the seismic events, which move inward in the focal region, but outward at the marginal. The left-lateral motions near the main fault indicate a small striking slip component caused by the Gaize earthquake. Finally, we discuss the potential of applying the derived spatially continuous 3-D displacement fields to determine the high-resolution 3-D strain fields of the Gaize earthquake, which provide important knowledge for assessing the source mechanism. © 2014 Springer Science+Business Media Dordrecht.

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