2005 年 58 巻 1 号 p. 15-28
We evaluated local site effects and Qs-values in the western part of Kanagawa Prefecture, Japan by a spectral inversion method using the ground motion data from nine middle class events that occurred near the target area. The results were as follows: (1) Qs-value was approximated to be Qs=20×f in the frequency range of 1-20Hz by assuming the geometrical spreading factor to be r-1. (2) The seismic moments evaluated in this study were slightly larger than those of previous studies. (3) The stations in the southern part of Ashigara valley showed high amplification at around 1Hz. (4) The relative site factors in reference to KNO coincided with the theoretical amplification factors calculated for one-dimensional subsurface structure models with SH-wave input motion from the layer of Vs=1200m/s.