| 講演要旨(和文) | | 盛岡市では複数の地震時の高密度アンケート調査から，市内の数km以内の狭い範囲内で震度が1ないし2程度異なることが知られている．盛岡市青山地区および本宮地区において，48地点で稠密極小アレイ微動観測，47地点で単点微動観測を実施し，微動H/Vおよび位相速度を用いて，表層地盤のS波速度構造の推定を試みた．また，30m平均S波速度を算出し，工学的基盤からの地盤増幅率を算出した．青山地区においてJ-SHISよりも実測の方が多くの地点で250m/s以下の遅いS波速度となり，ほぼ全ての地点で，実測で得た地盤増幅率の方が大きい．また，過去の震度分布と比較した結果，震度が大きかった東側で増幅率の値が1.6〜2.5と大きく，震度の低い西側でも増幅率の値が1.2〜1.6と小さいことが確認できた．本宮地区においてはS波速度が全体的に300〜400m/sと速くなり，地盤増幅率の値も1.0〜1.4と小さい． |
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| | 講演要旨(英文) | | In Morioka City, it is known from the high density questionnaire survey at the time of several earthquakes that the seismic intensity differs within the narrow range of several kilometers in the city. In Aoyama and Motomiya areas of the city, we conducted microtremor observations at 48 points with a miniature array and ones at 47 points with a single seismograph, and estimated shallow S-wave velocity structures using microtremor H / V and phase velocities. 30 m average S-wave velocities (AVS) were calculated from estimated S-wave velocity structure models, and site amplification factors from engineering basements were calculated from AVSs. In Aoyama area, estimated S-wave velocities were slower at more points than those from the J-SHIS, and site amplification factors obtained by the microtremor measurements were larger at almost all points. Moreover, as a result of comparing with seismic intensity distribution map estimated by our previous questionnaire survey, it was confirmed that amplification factors were large at 1.6 to 2.5 on the east side where seismic intensities were large, and site amplification factors were small at 1.2 to 1.6 on the west side where the seismic intensities were slightly low. In Motomiya area, the S-wave velocities were generally high at 300 to 400 m / s, and site amplification factors were also low at 1.0 to 1.4. |
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