抄録
An optimization technique under the unconstrained condition was introduced into earthquake engineering for the purpose to elucidate dynamic characteristics of the ground and building during an earthquake. In this report a main effort was paid for the estimation of the underground structure at SMAC site in Hachinohe city, where a very strong motion had been recorded at 1968 Tokachi-oki earthquake. Known quantities are a couple of seismic records at the free surface and at 50m in depth. Structural parameters to be optimized are S wave velocities and Q values. Flows of optimization procedure are illustrated in Figs. 5 and 6. Optimal spectral ratio between two seismometer positions shows a good agreement to that by the observation (see Fig.7). Physical meaning of the results by this technique was also investigated.
