摘要：We investigate the origin of variation of teleseismic P phase waveforms recorded at Matsushiro Seismic Array System. Short-period, vertical component waveforms from three source regions were analyzed separately in the frequency domain. Observed variation is mainly attributed to the site effects, which are frequency dependent and strongly depend on the incoming azimuth. Such variation is not seen for the pre-event noise spectra. The secondary wavefield that is excited by the incident P phase is the likely cause of the observed waveform variation.
