Abstract
Relationship between Fourier amplitude and phase of an earthquake ground motion is discussed using near-field strong motion records of the 2000 Western Tottori earthquake. According to the factorization theory, earthquake records are decomposed into minimum-phase-shift (MPS) and all-pass functions. Fourier amplitude of MPS is equals to that of earthquake records and is in inverse correlation to Fourier phase of MPS. Moreover the H/V spectral ratio is related to H-V MPS phase difference. It is due to a fact hat Fourier amplitude and phase of MPS are related with each other in terms of the Hilbert transforms.
