Determination of shear wave velocity structures from spectrum analyses of short‐period microtremors(1992)

Kohji Tokimatsu (Tokyo Inst.of Tech)& Yasuo Miyadera(Tokyo Inst.of Tech)・ Shinichi Kuwayama(GEOTOP) 

■掲載紙:Proceedings of TENTH World Conference on Earthquake Engineering,p253-258

 Use of short-period microtremors is studied for the evaluation of shear wave velocity (Vs) structures. Vertical ground surface motions of short-period microtremors are observed using circular arrays ofsix vertical sensors. Based on high-resolution frequency-wavenumber (F-K) spectrum analysis or the spacial auto-correla-tion analysis of these data, Rayleigh wave dispersion characteristics can be determined. The obtained dispersion curves are consistent with those determined by the steady-state Rayleigh wave method. An inverse analysis using these dispersion data permits estimating Vs structures of near surface soils. The Vs structures inferred by the proposed method show fairly good agreement with those obtained by the conventional down-hole method. These findings indicate that the use of short-period microtremors is effective for estimating Vs structures of near surface soils.