GPS and InSAR Inversion for Coseismic Deformation Field and Slip Distribution of the Ms7.0 Jiuzhaigou Earthquake

Abstract

On August 8, 2017, an Ms7.0 earthquake occurred in the city of Jiuzhaigou, Sichuan, China. We processed the European Space Agency ascending-descending Sentinel-1A/IW monitoring data, with Interferometric Synthetic Aperture Radar (InSAR) small baselines subset techniques and permanent scattering interferometry techniques for interference processing. We obtained the initial InSAR coseismic deformation interference results of the earthquake, and then used the global navigation satellite systems (GNSS) coseismic observations to calibrate the InSAR results. The InSAR coseismic deformation fields show that the maximum displacement of the surface deformation caused by the earthquake is about 20 cm in the line-of-sight direction, and the coseismic deformation filed has an asymmetric distribution. In this study, InSAR technology has achieved some results in surface deformation monitoring and digital elevation model acquisition due to its advantages of all-weather, all-day technique with the ability to penetrate cloud. And the GNSS can obtain single-point high-precision and high accuracy positioning. Combined, these two data types can ameliorate errors that are caused by satellite orbit error, surface conditions, and temporal irrelevance, which are difficult to eliminate in InSAR data. The technique can also realize the effective unification of GPS technology with high time resolution, high plane position accuracy and InSAR technology with high spatial resolution and high elevation deformation accuracy. It was shown in previous research that a single-orbit radar dataset could not accurately reflect a coseismic deformation field on the surface of the Earth. The novel contributions of this paper are as follows. First, we used ascending-descending InSAR data and various GNSS dataset to improve surface deformation information accuracy. Second, we compared the displacement variables obtained by using only sentinel-1A data with the combined sentinel-1A data and GPS CORS site data.