The hybrid slip model used to generate a finite fault model for near-field ground motion estimation and seismic hazard assessment was improved to express the uncertainty of the source form of a future earthquake.In this process, source parameters were treated as normal random variables, and the Fortran code of hybrid slip model was modified by adding a random number generator so that the code could generate many finite fault models with different dimensions and slip distributions for a given magnitude.Furthermore, a simple method to choose an optimal one from these generated models was proposed.The 1994 Northridge earthquake was taken as an example to demonstrate the procedure of the application of the improved model.Three rock stations, LV3, MCN and PCD, in near-field were used to compare the simulated ground motion from the improved model and optimal model with the observed one.The agreement between them in the periods of interest indicates that the improved model and the method to choose the optimal model are available for the engineering practice of ground motion estimation.
