| 講演要旨(和文) | | 2014年11月22日の長野県白馬村を震源とした長野県北部の地震では，白馬村や小谷村を中心にした地域において建物，道路・鉄道，斜面崩壊などの地震被害が生じた。とくに，白馬村堀之内や三日市場では，狭い範囲に全壊家屋が集中した。これらの地域では，本震の強震記録が観測されておらず，どの程度の強さの地震動であったかについては不明な点が多い。とくに，堀之内地区は，過去の地震においても被害を受けたことがあり（信濃毎日新聞社，1998），被害が狭い地域に集中した原因として局所的な地盤増幅効果も無視できないと考えられる。本研究では，白馬村堀之内および三日市場を中心とした地域で余震観測と微動観測を実施し，同地域での地震動と地盤増幅特性の関係を明らかにすることを試みた。 |
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| | 講演要旨(英文) | | Heavy damage was experienced in Hakuba village, Nagano prefecture during the 2014 Nagano-ken Hokubu earthquake. In particular many wooden houses were collapsed at Horinouchi, in the village. Characteristics of ground shaking during the main shock are not known in the area due to no availability of strong motion records. However, it has been known that this area was suffered in past several earthquakes. This suggests site amplification may be one of the reasons for the heavy damage during the earthquake. We conducted aftershock observation area and microtremor exploration at 13 station in the damaged to estimate site effects. Ground motion at periods of 0.5 to 1 second is dominant in the damaged area. Shallow soil down to 30 meters are responsible for the amplification. We also found a lateral variation of the shallow S-wave velocity near the Kamishiro fault. |
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