兵庫県南部地震の余震記録を用いた神戸市東灘区の地盤増幅特性の評価

概要

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Site effects in Higashinada, Kobe city were estimated from aftershock records of the 1995 Hyogo-ken nanbu earthquake. First, source spectra and site effects were separated by an inversion of S-wave ground motion spectra. The shapes of source spectra can be explained by the w^<-2> model. Amplification characteristics at all sites can be classified two types. The one obtained at sites in Rokko island shows the amplification decrease drastically between 2 and 3 Hz. The other shows 3-5 times amplification at the same frequency range. It is possible to explain the site effects by 1-D multiple reflection method except seismic intensity VII area. However, amplification at sites with seismic intensity VII can not be explain by it. This suggest that the site effects of heavy damaged area might include 2-D effects of underground stricture. Second, we determined V_s structures and Q_s of sedimentary layers by a fitting of observed amplification to theoretical one. The obtained of V_s structures are consistent with other result by different methods.
1998-07-30