Source model of 2016 Mw6.6 Aketao earthquake, Xinjiang derived from Sentinel-1 InSAR observation

Abstract

On 25 November 2016 (14:24:30 UTC), an Mw6.6 earthquake occurred in Aketao county of Xinjiang. We derived the coseismic deformation field of the earthquake from ESA's Sentinel-1B images and inverted the fault geometry and slip distribution by using a homogenous half-space elastic model and the Steepest Decent Method (SDM) program. The slip model shows that the rupture plane is about 68 km in length and 40 km in width and has an average strike of 105.2°SE and an average dip of 76.0°S. The average amount of slip is ∼0.16 m and the maximum amount of slip is 0.59 m. The estimated seismic moment is 1.31 × 1019 N·m and the corresponding moment magnitude is Mw6.68. The dislocation is mainly distributed in the depth of 5–22 km, where the rupture center is located at 39.17°E, 74.38°N, and a depth of ∼8.8 km, so this earthquake is a shallow earthquake. In terms of the tectonic settings, the earthquake was triggered by the release of residual stresses on the seismogenic Muji fault. The ruptures were stimulated simultaneously by the main shock, which made the slip distribution pattern of a strike-slip fault with a double fracture. Due to the tectonic setting and the seismic gap between the ruptures, the Muji fault would have a risk of rupture to some extent and trigger an earthquake in future. Keywords: Aketao earthquake, Differential interferometry, Coseismic deformation, Focal mechanism inversion