A hybrid method of earthquake forecasting based on numerical simulation and seismicity statistics : An application to China Seismic Experimental Site

Earthquake forecasting using numerical methods has recently been given much attention. Most previous explorations were trapped by calculation time steps, which generally refer to a long time. In this paper, a new numerical forecasting method with a shorter duration time is explored and applied to China Seismic Experimental Site (CSES) based on a hybrid method. Considering active block theory and structural mechanical analysis, we used a three-dimensional finite element simulation to calculate the long-term stress variation. Then the co-seismic stress released by moderate earthquakes, which occurred after the last big earthquake for decades, was superimposed on local regions. The annual scale's seismic statistic for small earthquakes was also overlaid by reclassification and weighted calculation. Therefore, the duration of earthquake forecasting is shortened by involving an annual scale. We illustrated the graded seismic risk on southeastern margin of the Sichuan-Yunnan border from 2021 to 2030. The 2022 Lushan M(s)6. 1 earthquake, the 2021 Yangbi M(s)6. 4 earthquake, the 2021 Luzhou M(s)6. 0 earthquake, and the 2022 Luding M(s)6. 8 earthquake occurred in the high-risk area, but the 2022 Barkam M(s)6. 0 earthquake occurred in the low-risk region. The hybrid method presented in this paper solves the length of calculation step in numerical simulation applied to earthquake forecasting. It includes both physics-based numerical simulation and statistical seismological analysis. Furthermore, it provides a possible exploration approach for numerical earthquake forecasting and its application.