Temporal and spatial changes in the b-value prior to the 2021 Luxian MS 6.0 earthquake in Sichuan, China

Abstract

Using the seismic data collected since 2010 by the China Earthquake Networks Center and based on the maximum likelihood method, we analyzed the temporal and spatial anomalies of the b-value prior to the MS 6.0 Luxian earthquake on September 16, 2021. The results are as follows. (1) The Luxian earthquake broke the historical record of no M ≥ 6 earthquake occurring in the Huayingshan fault zone, revealing that the Huayingshan fault zone still has the seismogenic ability of medium and strong earthquakes. (2) Before the MS 6.0 Luxian earthquake, the b-values around the focal areas exhibited increasing–peaking–decreasing anomalous characteristics, indicating that this is an effective method of predicting the occurrence of moderate to strong earthquakes in the region. (3) In the past 10 years, the b-values of the middle segment of the Huayingshan fault zone have been relatively low, but the b-value of this section may be in an abnormal stage of slow increase, indicating that this segment may be in a stage of stress accumulation and concentration and is preparing for moderate to strong earthquakes. The middle segment of the Huayingshan fault zone may become the site of moderate to strong earthquakes in the future. We should continue to pay attention to it.

Keywords

• Seismicity
• b-value
• MS 6.0 Luxian earthquake
• seismic hazard