| 講演要旨(和文) | | 2018年9月6日北海道胆振東部地震（MJ 6.7）では，勇払平野東部に位置する気象庁の厚真町鹿沼観測点（JMA47004）で震度7が観測された．またK-NET鵡川観測点（HKD126）では1-2秒の強い地震動が観測され，この観測点周辺では強震動による建物被害が発生した．我々は，本地震時における強震動の生成要因を解明するため，高震度地域で臨時余震観測を実施しており，余震記録の比較を通して，この地域での地盤震動特性に大きな変化が見られると推測された．そこで，この地域における地盤震動特性の空間的変動を把握するために，単点微動観測を実施した．観測結果を基にH/Vスペクトル比を計算し，卓越周波数を空間的に比較すると，地形と対応した傾向がみられ，余震強震観測記録における結果とも調和的であった． |
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| | 講演要旨(英文) | | During the 2018 Hokkaido eastern Iburi earthquake, seismic intensity 7 was observed at the strong motion station JMA47004 in Atsuma town, Hokkaido. And sever building damage occurred around HKD126 station which recorded 1-2 sec strong power ground motion. We have carried out temporary strong motion observation after the mainshock. We compared the aftershock records between HKD126 and hillside temporary stations. From this comparison, it was known that there are large differences in site amplification around 1-2 sec in this area. To estimate the spatial variation of the site amplification in this area, the single-station microtremor measurements were carried out. We analyzed the H/V spectral ratios form observed data. The predominant frequencies of the H/V spectral ratios are affected by the geomorphology and the tendency is similar to the comparison of aftershocks data. |
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