Source Parameters for the 2016 Mw 6.2 Italy Amatrice Earthquake Revealed by InSAR Observations

On August 24, 2016, an Mw 6.2 earthquake occurred in Amatrice, central Italy. In this paper, we use the ALOS-2 stripe-mode data and SENTINEL-1A wide swath data to obtain the coseismic deformation field by differential interferometry processing. InSAR results show that the earthquake caused significant deformation in central Italy. The largest subsidence reached 19.6 cm in the satellite line of sight (LOS) direction. Based on the InSAR and GPS coseismic deformation field data, we use a two-step inversion strategy to carried out the joint inversion of the seismogenic fault and to improve estimation method of the optimal dip angle and smoothness coefficient, and obtain the optimal fault slip distribution model. By using the single fault model and double fault model, the inversion show that the results of the double fault model are better than that of the single fault model. The data-model correlation coefficients of the inversion models under the two models are 0.85 and 0.89, respectively. The strike directions of the seismogenic fault are 160° and 158°, and the dip angles are 44° and 46°, respectively. The slip is mainly distributed at 5-7 km depth. The maximum amount of slip is up to 0.9 m at the depth of 5 km. The seismogenic fault is a 20 km long normal fault striking in the NW-SE direction which is a part of the Apennines fault zone. It shows that using InSAR and GPS data to carry out focal mechanism inversion and simulation analysis can accurately derive source parameters and provide data support for the analysis of seismic risk and fault nature.