軟弱地盤に於ける地震動

概要

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Denoting by Uw(t) the seismic vibrations of a ground with weak surface layer, and by Us(t) the seismic vibrations due to the same earthquake in ground without any surface layer, the writers-obtained the formula a+1/2Uw(t+h/v1)-a-1/2Uw(t-h/v1)=Us(t+H/V0) where H is the thickness of the surface layer, V1, V0 the velocities of propagation of seismic waves respectively in the surface layer and in its base beds. α is the ratio of V1 ρ1 to V0 ρ0, where ρ0 and ρ1 denote the densities of the respective layers, α is, therefore, the impedance ratio for wave propagation. This formula enables us to deduce from seismograms obtained of shocks through soft ground, the seismogram that would have been obtained at a ground that has no surface layer, αand H/V1 may be obtained from the amplitude period diagram of Uw(t).
東京帝国大学地震研究所,Earthquake Research Institute, Tokyo Imperial University,地震研究所の論文
1941-09-30