STIFFNESS MATRICES-BASED FORMALISM OF GROUND MOTION SYNTHESIS AND DIFFERENTIAL GROUND MOTIONS

摘要

We will present the definition of the differential ground motions on free-field ground surface, and then describe numerical examples to show the characteristics of the differential ground motions as well as those of near-field ground motions. The differential ground motions and the ground motions in this paper are synthesised using a discrete three fold Fourier transform of the analytical forms of seismic wave field. They are derived by a stiffness matrices-based formulation of the physical processes of propagation of the seismic waves generated by a kinematic fault rupture model buried in horizontally layered media. In consequence, the differential ground motions and the ground motions in this paper can be synthesised in quite accuracy, because the seismic wave field in our method is represented as a simple sum of plane waves with the complex amplitudes given by the analytical forms in frequency wave number domain.