Abstract
At 21:48 on 21 May 2021, an Ms 6.4 earthquake occurred in Yangbi County, Dali Prefecture, Yunnan Province. At present, uncertainty remains regarding the source parameters and deformation mechanism of the Yangbi earthquake. In this study, we determine fault geometry and slip distribution of the earthquake by InSAR analysis. Then, the Coulomb stress loading caused by the Yangbi earthquake is further analyzed. The results show that the moment magnitude of the Yangbi earthquake was Mw 6.14. The slip mainly occurred at depths of 3–13 km, with a maximum slip of approximately 61 cm at a depth of 6.98 km. The Yangbi earthquake was triggered by a blind fault in the NW-SE in the west parallel to the Weixi-Weishan Fault and its seismogenic fault exhibits strike-slip displacement. A large number of aftershocks were distributed along the fault rupture surface where the Coulomb stress increases. As the depth of the crust increases, the area where the Coulomb stress increases in the Yangbi earthquake, decreases. The occurrence of this earthquake also caused a significant increase in the Coulomb stress in the southeastern section of the Weixi-Weishan Faul. We should pay more attention to its seismic hazards.
Highlights
At 21:48 on 21 May 2021, an Ms 6.4 earthquake occurred in Yangbi County, DaliPrefecture, Yunnan Province (25.67◦ N and 99.87◦ E), with a focal depth of 8 km
For the two earthquakes of Ms 5.1 and Ms 4.8 in Yangbi, Yunnan Province in 2017, the focal mechanisms were obtained by the cut-and-paste (CAP)
The location of the seismogenic fault is further determined by the aftershock sequence relocated by the double-difference positioning method [1]
Summary
At 21:48 on 21 May 2021, an Ms 6.4 earthquake occurred in Yangbi County, DaliPrefecture, Yunnan Province (25.67◦ N and 99.87◦ E), with a focal depth of 8 km. 22:00 on 22 May 2021, the earthquake caused ~35 casualties throughout the state. This was the strongest earthquake in the area after the Ms 5.1 earthquake in 2017. The network of seismic stations in the area where the earthquake occurred are relatively dense, and there are at least eight broadband fixed seismic stations within a radius of 100 km from the epicenter [1]. For the two earthquakes of Ms 5.1 and Ms 4.8 in Yangbi, Yunnan Province in 2017, the focal mechanisms were obtained by the cut-and-paste (CAP). Method and three different velocity models [2]. We can obtain the seismic sequence, seismic surface wave velocity and deep structure of the Yangbi earthquake. Uncertainty remains regarding the source parameters and deformation mechanism of the Yangbi earthquake
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