Abstract
A strong motion record by means of a down-hole array was analysed in special references to wave types and the significance of down-hole array recordings in wave type identification was discussed. It was clarified that vertical and horizontal motions are composed mainly of P- and S-waves, respectively. General ideas learned from the analyses here in regard to the application of down-hole array recordings to wave type identification are as follows. (1) Dirct comparison of amplitude-depth relationships to the theoretical mode shapes of various wave types is an effective means for wave type identification. (2) Rayleigh waves can be identified from other wave types by means of the analysis of amplitude-depth relationships. (3) In some cases, amplitude-depth relationships are insufficient for the distinction between S-waves and Love waves because of the similarity of mode shapes. Additional information from frequency-time characteristics is useful to achieve the distinction. (4) Apparent horizontal velocity which connot be analysed by means of down-hole array recordings, is possibly the most effective means for the distinction between body waves and surface waves. This suggests the significance of horizontal array recordings.
