Regional ground motion prediction model for moderate magnitude earthquakes in Xichang, Sichuan, China

To explore the feasibility of establishing ground motion predicted models based on local earthquake data, meet the need of building western earthquake science experiment field, the characteristics of the distance, source and site effect of the prediction model were analysed based on 625 sets of ground motions of 21 moderate earthquakes in Xichang region in Sichuan. A prediction model based on characteristics of the local ground motions was established. Results show that the rate of distance attenuation in the acceleration response spectrum of Xichang area in the near field and short period is very large. When the fault distance is over 30 km, the rate of attenuation in each period tends to be equal. With magnitude increases, the value of the PGA and Sa decreases slower with distance, the acceleration response spectrum in short period decreases obviously faster than the long period. In short period, the predicted model in this paper is not much different from the NGA model, while in the long period, the estimated values of the model in this paper is relatively smaller, compared with the NGA model's values, and the NGA model overestimates the values obviously in the long period in Xichang's area. Compared with the domestic models, it is possible that a medium-strong earthquake in Xichang region will produce a larger PGA and a larger acceleration response spectrum in the short period. This study shows that there are significant regional differences in ground motion, so it is advisable to use local ground motion data to establish a ground motion predicted model. © 2021, Editorial Office of Journal of Vibration and Shock. All right reserved.