Characteristics for b-value of induced seismicity in Southeast of Sichuan Basin, China

Due to abundant shale gas buried beneath Southeast of Sichuan Basin, China (SBC), hydraulic fracturing operations are implemented since 2008. And large-scale shale gas mining began in December 2014. A rapid increase in the rate of seismicity in SBC since 2015, including the 16 December 2018 MS5.7, the 3 January 2019 MS5.3, the 17 June 2019 MS6.0, the 8 September 2019 MS5.4, the 18 December 2019 MS5.2, the 16 September 2021 MS6.0 and the 6 April 2022 MS5.1 earthquakes. Those earthquakes have caused much damages and many injures, which attracts a lot of attention from society and researchers. The related studies show that seismicity in SBC are induced by or related to hydraulic fracturing operation (Meng et al, 2019; Lei et al, 2019). In this work, we try to study the characteristics of local seismicity and explore the spatiotemporal characteristics of b-value in G-R relation to gain insight into the possible dynamic processes beneath the induced seismicity and assess the seismic hazards. The preliminary results indicate that the average b-value decrease from 1.17 to 0.75 when the 16 September 2021 MS6.0 earthquake occurred. And there is a substantial reduction of b-value before the 8 September 2019 MS5.4 earthquake. Moreover, the temporal variations for b-values don’t show a common pattern.   This study was supported by the Science for Earthquake Resilience (XH22011YA), “Real-time analyze characteristics of earthquake sequence by b-value and waveform” and National Natural Science Foundation of China (41974068), “Seismicity for Shale Gas Hydraulic Fracturing Stimulation”.   Lei X L, Wang Z W, Su J R. 2019. The December 2018 ML 5.7 and January 2019 ML 5.3 Earthquakes in South Sichuan Basin Induced by Shale Gas Hydraulic Fracturing. Seismological Research Letters, 90(3), 1099-1110, doi: 10.1785/0220190029. Meng L, McGarr A, Zhou L, Zang Y. 2019. An Investigation of Seismicity Induced by Hydraulic Fracturing in the Sichuan Basin of China Based on Data from a Temporary Seismic Network. Bulletin of the Seismological Society of America, 109(1), 348–357, doi: 10.1785/0120180310.