Abstract Based on the data from Ningxia regional seismic network, we determine the focal depth of the Zhongning ML3.6 earthquake using the first arrival P phase locating method, and the focal mechanism and moment tensor solution of the earthquake using gCAP inversion method. Then, using the simulation method of focal mechanisms and stress field, we calculate the relative shear stress and normal stress on the two nodal planes of focal mechanism of the Zhongning ML3.6 earthquake under current stress systems. The results show that the focal depth of the Zhongning ML3.6 earthquake measured by the first arrival P phase locating method and gCAP method are both 11 km. The focal mechanism of the earthquake is strike 242°, dip 63°, rake 8° for nodal plane I, and strike 148°, dip 83°, rake 153° for nodal plane II. The moment tensor result reveals that double couple component of the earthquake accounts for 97.07% of total moment tensor solution, indicating that the earthquake is a natural earthquake. Combined with spatial distribution of relocation of ML≥1.0 earthquakes from 2009 near the epicentre, regional geological structure, and relative shear stress, we conclude that the seismogenic fault of the Zhongning ML3.6 earthquake may be related to the NNW trending weak fault zone near the southeast segment of Tianjingshan fault. Under the NE direction compression of the northeastern Tibetan plateau, the earthquake is a right-lateral strike-slip seismic event caused by shear slip along NNW direction fault.
XU Yingcai,ZENG Xianwei. Source Parameters Determination of the Zhongning ML3.6 Earthquake in Ningxia on September 29, 2021[J]. jgg, 2023, 43(2): 215-220.
XU Yingcai,ZENG Xianwei. Source Parameters Determination of the Zhongning ML3.6 Earthquake in Ningxia on September 29, 2021[J]. jgg, 2023, 43(2): 215-220.