Study on the relationship between stress drop and earthquake activity in Hainan

Eighty-six earthquakes with magnitude greater than 2 were collected from 2011 to 2018 in Hainan and surrounding areas. Using the Brune disk model, the stress drop is calculated, and the direct relationship between the magnitude and the magnitude cannot be found after the stress drop result is processed. Four earthquakes with large magnitudes were selected. Through comparison of the stress drop values before and after the earthquake, it is found that after the stress drop event a larger earthquake may occur later to adjust the regional stress state. Based on the spatial contour map, it is found that the Beibu Gulf area has accumulated more energy in recent years and its background stress field is getting stronger.