| 講演要旨(和文) | | 平成28年熊本地震においては，益城町において4/14の前震(Mjma6.5)と4/16の本震(Mjma7.3)の2度にわたって震度7を観測し，断層近傍の住宅等に大きな被害を及ぼした．住宅等建物被害の分布1)においては，おおよそ本地震の地表地震断層2)近傍に被害が集中している傾向が確認されたが，断層直上であっても被害が少ない場所や，断層から離れていても被害が比較的大きな場所も確認されている．これらの現象は，地盤構造に起因する可能性が高いとの指摘もある．そこで，まず，はじめに，被害が大きい断層近傍の熊本平野を中心とした地域において，ボーリングデータの収集による初期地質モデルの構築を行った．次に，微動観測および地震観測記録の収集し，初期地質モデルの層厚・S波速度を調整した．最終的には，浅部・深部統合地盤モデルを構築し，建物被害分布との比較・検討を行った |
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| | 講演要旨(英文) | | The 2016 Kumamoto earthquake happened in Masiki town. And that, both of the foreshock [Mjma6.5] on April 14 and mainshock [Mjma7.3] on April 16 measured 7 level on the Japanese intensity scale of 7. The earthquake caused heavy damage to buildings etc. near the faults. On distribution of building damage such as houses, it was found that damage was heavier roughly near the surface earthquake faults which caused the mainshock. On the other hand, although some areas suffered slighter damage despite just above the faults, other ones suffered severer damage despite away from the faults. It is said that these phenomena are likely to be caused by subsurface structure.Therefore, first, in mainly Kumamoto plain near the faults where damage was severe, we collected boring survey data and developed initial geological models. Secondly, we obtained records of microtremor observation and earthquake observation, and then improved layer thickness and S-wave velocity structure of initial geological models. Finally, we modeled subsurface structure from seismic bedrock to ground surface, and then compared our models with building damage distribution and investigated the relation. |
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