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 1-20 Hz by assuming the geometrical spreading factor to be r-'. (2) The seismic moments evaluated in this study were slightly larger than those of previous studies. (3) The

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... ions in the southern part of Ashigara valley showed high amplification at around 1 Hz. (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= 1200 m/s.