Deformation of the 2013 Pakistan Mw7. 7 earthquake derived from sub-band InSAR

On September 24, 2013, an M(w)7. 7 earthquake strok Awaran, Balochistan Province, Pakistan, causing large strike slip up to 10 m. The coseismic deformation field, produced by TerraSAR-X short wave radar data, shows dense and extensive interference fringes which bring difficulties to thephase unwrapping. The sub-band InSAR is a new method for obtaining absolute phase, with a little or without phase unwrapping. This method shortens the bandwidth to increase the wavelength, and could reduce the number of fringes, which decreases the difficulty of phase unwrapping. However the noise and the extra interference of sidelobes will increase and the interferogram quality will decline, while the bandwidth reduces. More consideration should be taken into the parameter selection, noise filtering and processing flow, especially the selection of center frequency and bandwidth. In this paper, we first select the typical DEM experiment zone as the research area, and study the effect of parameter selection on sub-band InSAR with coherences and elevation errors as the evaluation index. Then, we apply the optimal parameter scheme to derive the coseismic deformation field of Pakistan. The coseismic deformation, extracted by sub-band interference, Landsat 8 optical images cross-spectrum correlation, offset tracking, and conventional DInSAR separately, are analyzed and compared with the deformation field from modeling. It indicates that sub-band InSAR performs batter in precision and noise level, in spite of the slight influence of decorrelation and loss of the extracted deformation field, compared with Landsat-8 and offset tracking. Therefore this method is more suitable to be applied in areas with large deformation and dense fringes.