Predicting the near-field strong ground motion based on uncertainties in asperities: an opportunity to reproduce the characteristics of the 1970 Tonghai earthquake (Ms 7.8)

Studying and understanding the characteristic ground motions of destructive earthquakes is very important in the prevention of earthquake disasters. In this paper, two 2018 Ms 5.0 earthquakes are used as an empirical Green’s function to reproduce the ground motion strength of the 1970 Ms 7.8 Tonghai earthquake. The present paper considers the uncertainties in the numerical simulation, the source model, the asperities, and the initial rupture positions. The obtained peak ground acceleration (PGA), the time history of the acceleration, and the acceleration response spectrum at each station are compared with the ground motion strength at corresponding stations for the Ms 8.0 Wenchuan earthquake to test the reliability of the ground motion simulation. The results show that the PGA of the one-asperity source model is the largest. With an increasing number of asperities, the ground motion strength decreases, and the earthquake duration increases, indicating that an increase in the number of asperities disperses seismic energy. The two-asperity source model is consistent with the real source model of the Tonghai earthquake. The acceleration time history and acceleration response spectrum at each station reflect the characteristics of the ground motion strength of the destructive Tonghai Ms 7.8 earthquake. Thus, reproducing the main ground motion strength characteristics of the Tonghai earthquake by combining the empirical Green's function method with two Ms 5.0 earthquakes is feasible.