Abstract:Based on travel time data of the first arrival P and S waves for earthquakes with ML≥1.5 from 2017 to 2022, using the Wadati method of signal earthquake and multi-station, we calculate and discuss the variations of the wave velocity ratio near the epicenter of the September 16, 2021 MS6.0 earthquake in Luxian, Sichuan Province. The results show that before the Luxian MS6.0 earthquake, the wave velocity ratio near the epicenter decreased in 1 year and 3 months, then rose again from the low value to the mean value in half a year. The low value area of the wave velocity ratio was concentrated around the epicenter. In 2019, before the Weiyuan MS5.4 earthquake and Zizhong MS5.2 earthquake about 66 km northwest of the Luxian MS6.0 earthquake, the seismic wave velocity ratio around it also showed a similar decline to recovery change, with a decline time of about 2 years. The two earthquakes occurred in the process of recovery, and the wave velocity ratio continued to rise after the earthquakes until the Luxian earthquake occurred. The epicenters of the two earthquakes were also in the concentration area of the low value of the wave velocity ratio.
CHEN Lijuan,CHEN Xuezhong,LI Yan’e. Performance of Wave Velocity Ratio before Luxian MS6.0 Earthquake on September 16, 2021[J]. jgg, 2023, 43(5): 529-533.