Abstract:We calculate the apparent stress and b value using waveform data and earthquake catalogue respectively to analyze the stress change process of 2021 Luxian MS6.0 earthquake. Using Schuster statistical test method and statistical parameter P, we statistically test the correlation between small and medium earthquakes and the change of earth rotation rate before the earthquake. We analyze the instability of the focal area. The results show that the apparent stress of ML3.2-3.9 and ML3.5-3.9 shows an upward trend for more than 7 years before the earthquake, and the apparent stress before the main earthquake reaches twice the early level. Before the earthquake, the b value experienced a decline of 7 years, from 1.2 in 2014 to 0.8 in 2020. There is a strong negative correlation between apparent stress and b value before the earthquake, reflecting the stress enhancement process near the epicenter. The P value of earthquakes with ML≥2.0 near the epicenter is less than 1% from August 2020 to February 2021, indicating that the seismicity in the focal area is significantly related to the earth’s rotation about half a year before the Luxian earthquake during which time the crustal medium in the focal area was in an extremely unstable state.
CHEN Lijuan,CHEN Xuezhong,GONG Liwen et al. The Apparent Stress and b Value and the Relation between Earth’s Rotation and Small and Medium Earthquakes before the 2021 MS6.0 Luxian Earthquake[J]. jgg, 2022, 42(11): 1133-1137.