Correction of coseismic deformation field associated with Wenchuan earthquake with GPS observables and InSAR adjacent track smoothing and fault slip inversion
Journal
Chinese Journal of Geophysics (Acta Geophysica Sinica)
Journal Volume
57
Journal Issue
5
Pages
1462-1476
Date Issued
2014
Author(s)
Abstract
In order to overcome the discontinuity of InSAR derived coseismic interferogram, a new method was proposed for the fringe correction with GPS observations and adjacent smoothening conditions. The GPS observations were employed to model the residual flat-earth phase and the interferometric fringes between adjacent orbits were smoothened with geometric constraints. The corrected coseismic deformation with ALOS/PALSAR images shows that the accuracy and smoothness were significantly improved. The RMSE of InSAR high coherent area reaches 3.6 cm with a 60% decrease, and that of low coherent area decreased by 40%. The smoothness factors are also improved by 33%. The correction results validated the feasibility and reliability of proposed method. The fault slip model was derived from the Okada dislocation model with InSAR and GPS deformation field. The results show that the main fault slip happened in 0~16 km depth in the crust in Yingxiu, Beichuan and Qingchuan area. The maximum slip is about 9.0 m located in Beichuan area. The inversion residuals of GPS and InSAR observations reach 5.5 cm and 9.2 cm respectively. The inversion accuracy of InSAR corrected deformation field was improved by 30%. The derived seismic moment from the refined fault slip model reaches 8.0469×1020 N·m.
In order to overcome the discontinuity of InSAR derived coseismic interferogram, a new method was proposed for the fringe correction with GPS observations and adjacent smoothening conditions. The GPS observations were employed to model the residual flat-earth phase and the interferometric fringes between adjacent orbits were smoothened with geometric constraints. The corrected coseismic deformation with ALOS/PALSAR images shows that the accuracy and smoothness were significantly improved. The RMSE of InSAR high coherent area reaches 3.6 cm with a 60% decrease, and that of low coherent area decreased by 40%. The smoothness factors are also improved by 33%. The correction results validated the feasibility and reliability of proposed method. The fault slip model was derived from the Okada dislocation model with InSAR and GPS deformation field. The results show that the main fault slip happened in 0~16 km depth in the crust in Yingxiu, Beichuan and Qingchuan area. The maximum slip is about 9.0 m located in Beichuan area. The inversion residuals of GPS and InSAR observations reach 5.5 cm and 9.2 cm respectively. The inversion accuracy of InSAR corrected deformation field was improved by 30%. The derived seismic moment from the refined fault slip model reaches 8.0469×1020 N·m.
Type
journal article