COSEISMIC AND EARLY-POSTSEISMIC DISPLACEMENTS OF THE 2015 MW8.3 ILLAPEL (CHILE) EARTHQUAEK IMAGED BY SENTINEL-1A AND RADARSAT-2

In this study, we present coseismic and poseismic surface displacements caused by the 2015 MW 8.3 Illapel (Chile) earthquake with Sentinel-1A (S1A) and RADARSAT-2 (RS2) SAR imagery. The Central Chile, where the earthquake occurred, is a great place to apply InSAR techniques. All RS2 and S1A pairs have good coherence including one pair with a three-year long temporal baseline. However, topographically correlated atmospheric effects significantly influence most of InSAR results, particularly those postseismic interferograms. We use Global Atmospheric Models (GAM) simulation to mitigate the effects of stratified tropospheric delays before implementing InSAR deformation time series analysis. Two global atmospheric models, ERA-Interim and MERRA are compared for their performance to reduce the atmospheric effects. The results show that MERRA data can reduce atmospheric errors from 10% to 44%, which is slightly better than those derived from ERA-Interim. Both co-and post-seismic deformation patterns have been captured by RS2 and S1A interferograms.