In order to verify the applicability of the stochastic finite fault method in simulating ground motions caused by subduction slab earthquakes

the 2021 Chiba

Japan Mj 6.1 subduction slab earthquake was taken as an example

and a total of 25 sets of surface and borehole station records within a range of 100 km around the epicenter were obtained from KiK-net and simulated by the stochastic finite fault ground motion method. The ground motion characteristics such as spectrum

duration

peak value

and spatial distribution of simulated and observed records were analyzed. Results show that the simulated and observed response spectra of pseudo-spectral acceleration (Aps) with 5% damping ratio were well matched in the band range of 0.1–10 Hz. The simulated records of duration model based on 70% energy duration were consistent with the observed records in the strong motion section. The simulated and observed peak ground acceleration (Apg) from the surface stations were in good agreement

and the Apg attenuation characteristics were basically the same. The Apg contours based on the simulated records were very similar to the observed Apg contours. In addition

the simulated results and observed records were compared with the results of commonly used ground motion prediction equations (Zhao16) for subduction slab earthquakes in Japan. Results show that the Apg prediction of Zhao16 was generally overestimated

and the Aps prediction was underestimated and overestimated to some extent at low and high frequencies respectively

which may be caused by the basin effect and soft soil layer in the study area. The research results can provide basis for the applicability of the stochastic finite fault method in ground motions caused by subduction slab earthquakes

and will offer further reference for exploring the application of the method to areas with similar tectonics in China.