Abstract Based on the seismic data for Luxian MS6.0 earthquake provided by Sichuan and surrounding provinces’ seismic network, using the CAP inversion method, we calculate source parameters, like focal depth, moment magnitude and focal mechanism. From the focal mechanism of 155 events occurring in those regions, using the MSATSI code, we derive the tectonic stress field in the Sichuan basin before the earthquake. The results indicate that the focal depth of the Luxian earthquake is 3 km, and the moment magnitude is MW5.36 with pure thrust faulting rupture. Tectonic stress before the event shows that the directions of both maximum and the intermediate principal compressive stress are almost horizontal, and the strike angle of the maximum principal compressive stress is about 101° near the epicenter. Under such stress framework, the optimal sliding fault is pure thrust, completely consistent with the focal mechanism of the Luxian earthquake. This event faulting is mainly controlled by the lateral force, suggesting that the southwestern part of the Sichuan basin is involved in the eastward expansion of the Tibetan plateau. This event is the result of activation of the shallow detachment fault under this tectonic background. Based on the source properties and background stress, we infer that the seismogenic fault of the Luxian earthquake may not be the Huayingshan fault, but a very shallow caprock slip-type fault between its branches.
LIU Huimin,XIE Zujun,LI He et al. Source Properties and Characteristics of Tectonic Stress Field before the September 16, 2021, Luxian MS6.0 Earthquake in the Sichuan Basin[J]. jgg, 2022, 42(11): 1138-1142.
LIU Huimin,XIE Zujun,LI He et al. Source Properties and Characteristics of Tectonic Stress Field before the September 16, 2021, Luxian MS6.0 Earthquake in the Sichuan Basin[J]. jgg, 2022, 42(11): 1138-1142.
