Coseismic deformation field of the Jiuzhaigou Ms7.0 earthquake from Sentinel-1A InSAR data and fault slip inversion

We processed the Sentinel-1A/IW data with InSAR technology and generated the surface deformation fields caused by Jiuzhaigou M(s)7.0 earthquake occurred on August 8 2017. The result shows that the overall deformation field caused by this event follows the NW direction. Main deformation region is about 50 km X 50 km delimited by Tazang, Minjiang and Huya faults. The maximum displacement reaches about 14 cm, and the minimum value is about 22 cm in LOS. The displacement field indicates a left-lateral strike-slip movement of seismogenic fault. Based on ascending InSAR deformation field only, we carried out the slip distribution inversion by using a fault model with single fault plane and medium dip angle. The inversion results indicate an obvious slip concentrated area located in 1 similar to 15 km in depth. The maximum slip is about 0.86 m. The moment magnitude is M(w)6.5, consistent with previous results from seismic data inversion provided by USGS. We can see that the rupture of this event has filled the rupture gap of four earthquakes larger than M(W)6.0 occurred in 1973 and 1976. The coseismic Coulomb stress change shows that the rupture has produced two stress increasing zones in the depth of 10 km, similar to(3 similar to 5) X 10(5) Pa. This will increase the possibility of aftershocks in this area. A large stress decreasing zone delimited by Minjiang and Tazang fault indicates the releasing of accumulated stress before the rupture. Thus, the possibility to trigger further strong aftershocks in this region is relatively small.