| 講演要旨(和文) | | 2016年熊本地震により熊本県益城町には甚大な家屋被害が生じた。中澤他(2016)の調査によれば、熊本市東区と益城町の間における家屋被害は阿蘇火山火砕流堆積物から成る台地縁辺の傾斜部下半分に集中した。我々は、そのような地形的特徴と地盤特性との関係を明らかにするために、常時微動による調査を実施した。微動データの解析結果によれば、被害の集中した傾斜部下半分では、相対的に被害の小さいその隣接地域と比較して、深さ30mまでの平均S波速度が平均20%ほど低いことが明らかにされた。 |
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| | 講演要旨(英文) | | Extensive building damage occurred in Mashiki Town and its surroundings, Kumamoto Prefecture, by the 2016 Kumamoto Earthquake. Following the survey of Nakazawa et al. (2016), building damage in the area between Mashiki Town and Higashi-ku of Kumamoto City was concentrated in the lower slope at the margin of the upland formed of the pyroclastic flow deposits from Aso Volcano. We conducted microtremor survey to examine the relation between the topographical features and the ground characteristics. As the results, the analysis of microtremor data showed that the average S-wave velocity to a depth of 30 m in this damage-concentrated area was, on average, about 20% smaller than that in the adjacent areas with less damage. |
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