Double rupture event in the Tianshan Mountains: A case study of the 2021 Mw 5.3 Baicheng earthquake, NW China

Abstract On March 23, 2021 (21:14 universal time coordinated), an Mw 5.3 earthquake occurred in Baicheng County in Xinjiang, northwestern China, according to the United States Geological Survey. The earthquake produced a 4-km-long surface rupture at the epicenter, which is generally rare for earthquakes of magnitude 5.3. Thus, investigating the Baicheng earthquake is crucial for understanding the seismogenic structure of the region. We obtained the interferometric synthetic aperture radar deformation field and inverted the slip distribution of the Baicheng earthquake using Sentinel-1A satellite data and surface rupture data. The results indicate that the surface deformation area was elliptical, with long and short axes of approximately 20 and 10 km, respectively. The seismogenic structure is a left-lateral strike-slip fault with a small dip-slip component and strike and dip angles of 248° and 70°, respectively. Two other slip centers were also observed at 2 and 8 km beneath the surface in the dip direction. The maximum slip at 2 km was 0.45 m. Shear deformation between the Tarim Basin and Southern Tianshan Mountains was responsible for the strike-slip features of the Baicheng earthquake.