ARRAY OBSERVATION OF AFTERSHOCKS OF THE 1995 HYOGOKEN-NAMBU EARTHQUAKE AT HIGASHINADA WARD, KOBE CITY

概要

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An array observation of aftershocks was made in Higashinada Ward, Kobe City, to estimate the site responses of severely and slightly damaged areas. Four temporary observation stations were installed just after the mainshock in the vicinity of the permanent station by the Committee on Earthquake Observation and Research in the Kansai Area (CEORKA) [1]. In several aftershock seismograms the peak values of the observed ground accelerations and velocities at the soil sites were 3- to 10-fold those at the rock site. Waveform simulations using a dislocation point source in a horizontally stratified medium revealed that the large amplifications of S-waves at the soil sites in the heavily damaged area were caused by very thin (less than 10m) and very low-velocity surface layers. The heavy damage caused by the mainshock therefore should be due mainly to the geological surface conditions.
日本自然災害学会の論文