Review and case analysis of dynamic triggering of shallow earthquake in the Weiyuan area, Sichuan Province

Dynamic triggering refers to the phenomenon of teleseismic waves propagating to some areas in a near-critical stress state, thus triggering earthquakes. Shallow earthquakes are the type of earthquakes that are most commonly triggered. Researching the dynamic triggering of shallow earthquakes can enhance understanding of the seismogenic mechanism and produce additional information about the state of shallow faults, which has great importance for earthquake prevention and disaster reduction. This article reviews possible mechanisms and detection methods of dynamic triggering, focusing on several case studies of triggered shallow earthquakes in different tectonic settings. Furthermore, by using continuous recordings from a dense seismic array in the Weiyuan area of Sichuan Province from November 2015 to November 2016, we investigated whether seismic activities in the shale gas extraction areas were influenced by the dynamic triggering of teleseismic waves. The results revealed that the seismicity in the area increased significantly within 12 hours of the M_W7.4 Tajikistan earthquake on December 7, 2015, and exhibited characteristics of dynamic triggering. However, after carefully analyzing the temporal and spatial distribution of the earthquakes in the Weiyuan area following the Tajikistan earthquake, we found that the migration of the enhanced seismic activities exhibited characteristics of fluid diffusion, suggesting that these shallow earthquakes were more likely induced by industrial injection.