Multi-Sensor Geodetic Observations and Modeling of the 2017 Mw 6.3 Jinghe Earthquake

Abstract

The Mw 6.3 Jinghe earthquake struck Xingjiang Province, China, on 8 August 2017 (05:15:04 UTC); the epicenter was near the Kusongmuxieke Piedmont Fault (KPF) of the northern Tian Shan Mountains. We used multi-source and multi-track satellite Synthetic Aperture Radar (SAR) imagery and Interferometric SAR (InSAR) techniques to reconstruct the coseismic displacement field from different line-of-sight geometries. To reduce the phase artifacts, we employed multi-temporal scenes acquired by Sentinel-1, and reconstructed the coseismic deformation through a temporal averaging strategy. Together with a single interferometric pair obtained using the Phased Array type L-band Synthetic Aperture Radar 2 (PALSAR2) sensor aboard the Advanced Land Observing Satellite 2 (ALOS2), we obtained five displacement maps with slightly different viewing geometries; all of which were used to constrain a geodetic inversion to retrieve the fault geometry parameters and slip distribution. Based on the focal mechanism and regional geology, we constructed multiple fault models that differ in dip direction (south and north dipping), and various striking angles. Both models fit the InSAR displacement maps, but have slip distributions of different depths. The slip depth of the south dipping model, with a dip of ~42°, is the most consistent with the relocated earthquake sequence and regional geological structure. Through the geodetic inversion, the maximum slip (0.25 m) occurred at 14.05 km and the associated rake was 89.56°. The result implies that the seismogenic fault is a blind thrust fault north of KPF (towards the foreland). Considering the relative locations of the suggested blind fault, the KPF, and the continuing north to south (N−S) shortening of the Tian Shan Mountains, this fault could be formed by the northward propagation of the regional fold-thrust belt.

Keywords

• coseismic deformation
• InSAR
• northern Tian Shan
• Jinghe earthquake