InSAR and GPS inversion for source parameters of the 2016 Mw6. 4 Meinong, Taiwan earthquake

On February 6, 2016, an M(w)6. 4 earthquake struck the Meinong district of Kaohsiung city in Taiwan, China. Many studies have been conducted on this event, most of which are based on seismic Data, while no consensus has been reached on its fault structure and focal parameters yet. Surface displacement obtained by InSAR technology is widely used in earthquake studies because of its high resolution and accuracy with large and continuous coverage. This study used InSAR and GPS data to investigate the focal mechanism and slip distribution of the 2016 Meinong earthquake. Using the dual-track differential interferometric SAR (D-InSAR) technology, we extracted the coseismic deformation field of this earthquake from synthetic aperture radar (SAR) data (both the ascending and descending) acquired by satellite ALOS2 and the ascending data by satellite Sentinal-1A. The results show that the maximum deformation occurred in the west of the epicenter with an uplift around 11. 2 cm. The uniform dislocation model and multiple peak particle swarm optimization (MPSO) algorithm were employed to determine the fault geometry of this earthquake based on the InSAR and GPS data. The results show that the rupture is a reverse fault with sinistral strike-slip with the average slip angle of 51. 5 degrees. The deformation center is at 22. 920 degrees N, 120. 420 degrees E with a depth of 12 km. The rupture plane is about 15 km long with a strike of 307 degrees and a dip angle of 16. 5 degrees. The optimal dip angle (15. 7 degrees), weighting ratio (18 :1) between GPS and InSAR and the smoothing factor (0. 06) obtained by the grid iteration method based on a non-uniform dislocation model, and the non negative least squares method are used to determine the detailed slip distribution. The results show that the maximum value of dip slip and strike slip are 51. 7 and 55. 3 cm, respectively. The moment magnitude of the non-uniform rupture model is M(w)6. 38, slightly smaller than that of GCMT (M(w)6. 4). The comparison between our research and previous work and the analysis of the regional faults indicate that a single fault geometry is more reasonable which can fit both the GPS and InSAR data well. We also find that the ruptured fault is a blind structure located between the Zouchen and Chishan faults with an SE-NW strike, dipping toward to SE. We infer this fault should be also related with the 2010 M(W)6. 3 Jiashian earthquake.