An Improved Source Model of the 2021 Mw 6.1 Yangbi Earthquake (Southwest China) Based on InSAR and BOI Datasets

• Published in: Remote sensing (Basel, Switzerland) Switzerland), 2022-10, Vol.14 (19), p.4804
• Main Authors: Lu, Hao, Feng, Guangcai, He, Lijia, Liu, Jihong, Gao, Hua, Wang, Yuedong, Wu, Xiongxiao, Wang, Yuexin, An, Qi, Zhao, Yingang
• Format: Article
• Language: English
• Subjects: Azimuth; Displacement; Earthquakes; Fault lines; Geology; Geometry; Interferometric synthetic aperture radar; Interferometry; Line of sight; Mathematical models; Parameters; Rivers; Seismic activity; Seismic hazard; Slip; Topography
• ISSN: 2072-4292; 2072-4292
• DOI: 10.3390/rs14194804

The azimuth displacement derived by pixel offset tracking (POT) or multiple aperture InSAR (MAI) measurements is usually used to characterize the north-south coseismic deformation caused by large earthquakes (M > 6.5), but its application in the source parameter inversion of moderate-magnitude earthquakes (~M 6.0) is rare due to the insensitive observation accuracy. Conventional line-of-sight (LOS) displacements derived by the Interferometric Synthetic Aperture Radar (InSAR) have limited ability to constrain the source parameters of the earthquake with near north-south striking. On 21 May 2021, an Mw 6.1 near north-south striking earthquake occurred in Yangbi County, Yunnan Province, China. In this study, we derive both the coseismic LOS displacement and the burst overlap interferometry (BOI) displacement from the Sentinel-1 data to constrain the source model of this event. We construct a single-segment fault geometry and estimate the coseismic slip distribution by inverting the derived LOS and BOI-derived azimuth displacements. Inversion results show that adding the BOI-derived azimuth displacements to source modeling can improve the resolution of the slip model by ~15% compared with using the LOS displacements only. The coseismic slip is mainly distributed 2 to 11 km deep, with a maximum slip of approximately 1.1 m. Coulomb stress calculation shows a maximum Coulomb stress increment of ~0.05 Mpa at the north-central sub-region of the Red River Fault. In addition, there is a small Coulomb stress increase at the Southern end of the Weixi-Weishan fault. The potential seismic risks on the Weixi-Weishan and Northwest section of the Red River faults should be continuously monitored.