Abstract
Concerning long-period component of the ground motions observed in various regions at the Central Chiba Pref. Earthquake in 2005; Mj6.0, we achieved the simulation analyses which were theoretically based on the wavenumber integration method assuming the point-source and the parallel-layered soil structure. There was the tendency that the ground motion orbit massively swelled up round in the horizontal plane at some observation points, which was adeptly explained by the superposition of calculation waves by two slip angles with determined independently, and it has been shown that the compatibility between the observed and the calculated waveforms are improved more than the simple source process model. Furthermore, we examined the quantitative variation by numerical computation that have to be assumed considering uncertainness of the ground motion due to the such complexity of slip angle at the earthquake-resistant design.
